My joke when I was in grad school was that my job was "being one of Doc Ock's arms." After all, outside of Spider-Man 2, fusion researchers don't use complicated prosthetic rigs to run their experiments; that's what grad students are for.
As an article for a lay person to understand the current state of fusion, I give this a 9/10.
As a book review, it's a 1/10.
Still appreciated and glad I read it, but it should be disqualified as a book review entry and just be allowed to stand alone as a primer on fusion and how close we are.
That's my thought. While often a good book review uses a response to ideas in the book as the seed for a broader essay (like the previous one on The Dawn of Everything did), this one didn't obviously rely on the book in any particular way.
I think the other negative for me is that the major point, which I take to be "fusion might actually be 30 years away", buttressed by the various high probability estimates, is kind of pulled out of nowhere. The only arguments I see are (1) all we ever needed was money and time, and (2) high Tc superconductors have made more experiments possible.
Those aren't bad arguments, but I would wish they could be fleshed out a little more. *Why* is so much money needed? (OK I can kind of start answering that myself, but it would be much better to have a pro read, and surely it must be covered in the book.) What are the nasty engineering or physics problems that have been overcome? That's not easy to do for an audience that may be intelligent but doesn't know all your vocabulary, but I'm told the book did it, so some of that could be laid out here, too.
Because the experiment needed had to be big. The two big bumps on the first graph correspond to "Build ITER" and "Build DEMO". It took us a long time to pull together enough money to build ITER.
High temperature superconductors allowed the experiments to be medium again, which decreased the cost by a factor of 10. We can now build a lot more of them, including from private capital.
The third factor is that China and Korea joined the game in about 2000. They've been spending more than anyone else and so are likely to finish their DEMOs (CFETR & K-DEMO) before 2040. I don't think that they're going to be first, so I didn't emphasize them as much, but they do provide more plausible paths to fusion.
There are nasty engineering and physics problems to overcome, but they aren't as important as the scale. And they take longer to explain than a book review.
I think you can do better. The experiment has to be big is just a way to rephrase we need a lot of money. You need to say *why* the experiment has to be big. Yes, I can at least start to fill it in for myself, but to make a connection to people who aren't familiar with the physics you need to tease that apart for them.
About half of the book reviews in the New York Review of Books over the last half century would be disqualified by a requirement to be more about the book than about the reviewer's own ideas.
This "book review" was plainly written by one of the authors or a close associate and is simply a summary of the book condensed into a blog post.
It shares the same fundamental flaw as the book: presenting some basic plasma physics and a bunch of lists of machines as if it were predictive policy analysis. Some PhD students decided to publish the first few pages of their literature review.
As far as I could tell, the technical content is correct. It is not necessary to fabricate facts to write a puff piece, it's a matter of picking the facts that provide a favorable spin to the story being told; figure 3 is a case in point, i.e., multiply some numbers to create exponential growth that can be compared to Moore's law.
Pointing out that the trend line does not continue creates a sense of failure being snatched from the jaws of victory.
I was experiencing cognitive dissonance up to seeing this figure. These book reviews have been good/excellent/superb, and this was my mindset when starting to read. Figure 3 slapped me around the face and I suddenly saw the 'review' for what it was.
Nothing wrong with switching things around to show a different perspective. Adding in a line to show a comparison with Moore's law is great marketing copy.
There are not facts in error per se but the review still reads like a puff piece. Even if we solve the significant fundamental plasma physics problems, there are significant engineering challenges involved in fusion that are barely mentioned or brushed under the rug. These include the difficulty of effectively injecting tritium fuel, parasitic power consumption, proliferation risk, and radiation damage to the reactor itself. More on that last point: consider that DT fusion neutrons (14 MeV) are much higher in energy than fission spectrum neutrons (peaked at ~1 MeV). In other words, each neutron produced is capable of dealing much more damage to structural materials than in the case of fission. This issue is already a problem for fission reactors and will only be worse for fusion.
Of course, expecting all of these topics to be dealt with fully in a single book review is to set a high bar. However when the author makes strong claims outside scientific consensus (eg, giving Renaissance Fusion, who do not have even a prototype, a 70% achieving fusion by 2040) the burden of proof is on them.
I’m happy to see resources spent on fusion research. However the challenge must be tackled with a clear eyed view of the difficulty at hand.
Two estimates I've seen for the additional cost to adding intermittent sources of power put it at $40 and $50 per MWh above the base cost at 50% of production, due to transmission upgrade costs and idle backup generation. This goes up so that they didn't even make estimates above 80-90%
There is a large target for either low carbon baseload or energy storage that wind and solar can't reach as is, so that I see fusion as a good candidate. In particular it seems like there's no appetite for funding nuclear to the wider world due to proliferation concerns where there might be for fusion
$40 to $50 per MWh adds to perhaps 20 for the original power in PV in the US. That still makes it competitive with coal and natgas (~60), and much cheaper than fission (~100 to 120). So that's a big bar to leap.
There is absolutely no way any of the mainstream fusion designs discussed here will be cheaper than fission. Literally every single piece of the plant is more expensive and complex. Deuterium is not cheap, and the tritium is breathtaking even if we figure out how to breed it, which is an unsolved problem.
Even CFS puts the LCOE in the 200/MWh range for post-FOAK. We'll just build more batteries.
I live in California, land of wind and solar to the max, plus the highest electricity rates anywhere, increasing faster than anywhere else, and major reliability issues -- like planned blackouts because the solar power goes off just when the air conditioning and TVs go on -- so you will hopefully understand why I regard "proven" as more of an ideological than empirical statement.
California is a great example of why a reliable, clean, energy source is badly needed (I'm agnostic on "cheap").
But the way Fusion Reviewer sets out his stall, there's a hell of a long chain of "ifs" - IF public research gets government funding and IF private investment capital takes up the slack and IF ITER works and IF these other things work and IF we decide on what is the best design and so on and so on.
Other people in the thread are pointing out weak links in this chain. I get that he's an enthusiast (a fusioneer!) and so all his geese are swans, but criticism can't be brushed off simply by "you're a wet blanket".
I do think that we should invest in wind and solar as well. It is proven that they work at the scale we've deployed them, but not that they will work for 100% of our electricity. Mechanical energy storage solutions might work, but they have not been proven to work at the scale we need. Since there is uncertainty here, we should pursue multiple options.
If fusion is what we're going to end up using in the long run, we might as well get to where we can use it in the medium run too.
I agree completely, but if we could only do one form of energy resource development at a time, fusion would not be my choice.
FWIW, I'm a MarcorLife proponent, so my main interest WRT fusion is powering really large space habitats beyond Saturn's orbit. Fusion is clearly the best choice. Locally, though, I'd put more efforts into improved batteries and other forms of energy storage. (Solar heated molten salt has its points. So do various other options.)
OTOH, the original presumption is false. We can and do invest in more than one option at a time. I don't think we're over-investing in fusion.
All that said, while I found it a very interesting argument, I didn't think of it as a book review at all. (And I couldn't really figure out how to combine those "estimates of success" to derive a final "these are the odds". I don't really think those estimates are independent.)
Fusion is extremely intermittent. At present it typically happens for a microsecond, once every few weeks. This is just one of several rather intractable engineering problems with it.
Those other problems taken together make fusion unlikely to be worth investing in for any purpose other than curiosity.
Re. why invest in fusion over other sources? My leading order answer is that I don't believe it's a dichotomy, and even if it were, it's good to not put all eggs in basket.
Re. climate change timescales and energy transitions, potentially, but you need low carbon base load. If you're (politically?) brave, you go for fission. If you're smart, you solve affordable fusion. I don't see many other options for base load unless energy storage and grid management improve a lot.
Keep an eye on SPARC in particular for faster fusion.
But yes, let's build 'renewables' as fast as reasonably possible.
To handle climate change you don't plan of fission or fusion power unless you're willing to handle a temperature rise of 2.5C+. They will/would take too long to come on-line.
What you do is really build out solar and wind (and other) sources of energy while at the same time really building out LOTS of separate storage facilities. I'm not a fan of Hydrogen, but if you overbuild the generation, you can use excess when you have it to generate fuel of some sort. (My preference would be a kind of gasoline derived from atmospheric CO2. That would be energy intensive, but you ARE dealing with an energy surplus.)
The high estimate for Renaissance Fusion is partly because I know them and am impressed by some of the ideas that they have not yet made public. I think that's my statement farthest from scientific consensus. Maybe my prediction for Type One Energy too. If you do downgrade these estimates, the headline prediction does not change by much.
The problems that you describe are real, but I don't think that any are insurmountable. The 14 MeV neutrons should be almost entirely absorbed by the tritium breeding blanket. The book has an entire chapter on proliferation risk. I have not looked into the other problems in detail.
Stellarators are perhaps the worst idea in fusion. Well, no, ICF is, but they're close.
Compared to a tok, they require dramatically larger numbers of individual magnets, the magnets (usually) have to be fantastically complex, the machine has to be built to a standard that is difficult to meet (to the point that NCSE was abandoned), maintenance is practically impossible, and their aspect ratio is absolutely terrible which leads to bad economics and really expensive tritium breeding.
The world's best stellarator currently posts numbers roughly equivalent to those being generated by toks in the 1980s. They have two orders of magnitude in triple product to meet current results. Crossing those two orders led to all sorts of unexpected new problems in the toks, which is why the graph flattened. There is no reason to suspect that the same will not happen in stellarators.
I'm not sure what secret sauce Renaissance claims to have, but it seems unlikely they have overcome *all* of these issues, especially the last one.
Wow. What Hossenfelder writes isn't just a "not rosy" take, she's basically claiming the entire field of fusion research is fraudulent to the core. Having read that my interest in fusion is now sub zero. Assuming that's true and I see no reason why it wouldn't be, all government research for fusion needs to be cancelled, right now.
I mean, I think I'm a pretty average lay man with an superficial interest in fusion power, but I have known the difference between plasma break-even (which I think is the same as scientific break-even, Q=1) in OP and total break-even (engineering break-even, claimed to be ~Q=5 in the article, so 5 times as much) for a while now. This is explained in many articles I've encountered as well as in the OP, so it's not like this is some obscure thing that the fusion community is trying to hide from us.
Plasma breakeven is the same thing as scientific breakeven.
The same plasma can have different engineering breakeven, depending on how the rest of the experiment or power plant is designed. ITER should have Q=10, but not hit engineering breakeven. If you took off a lot of its diagnostics and didn't have four different ways of heating the plasma, then it probably could get engineering breakeven. But it wouldn't be as good of an experiment. We want to get lots of data about what the plasma is doing and we want to try out multiple versions of different subsystems to see which one works best.
The point here is that this "Q-plasma" take isn't something anyone cares about. Take the non-book-review, it says:
"We also measure the success of fusion using Q ... Q is entirely determined by the triple product."
That's the definition of Q-plasma to use Hossenfelder's (?) terms. For fusion to be a success in the way everyone else thinks about it means that it not only needs an "engineering breakeven" of >1 but it needs to have that with also a chance of being profitable ("financial Q") and relatively low risk to run the power plants. Note that profitability is so far from fusion researcher's minds it's apparently not even worth a mention in the article, have they even ever attempted to calculate this?
The issue here is that if fusion researchers really are defining success purely in terms of plasma energy balance, then how much effort can they be putting into researching all the rest of it? The article states clearly that "success" for fusion is as simple as improving Q-plasma. That's not a type of success meaningful in the real world.
And how can anyone defend the comments of the ITER guy?
"ITER will be the first fusion reactor to create more energy than it uses. Scientists measure this in terms of a simple factor—they call it Q. If ITER meets all the scientific objectives, it will create 10 times more energy than it is supplied with"
That is a directly misleading statement, isn't it?
"There is also ‘engineering breakeven', when you get more energy out of the entire power plant than you put in, and ‘economic breakeven', when you get more money out of the entire power plant than you put in. We need to get scientific breakeven first."
There have been some people who try to calculate the profitability, but a lot of the relevant questions are unknowable until we build a full scale experiment. For example, there has been some discussion elsewhere in these comments about the maintenance schedules for materials exposed to 14 MeV neutrons. We won't know this until we get a good source of 14 MeV neutrons, which means we need a fusion reactor.
I would not have explained Q in that way. So no, I'm not defending those comments. They're also from an interview from 2006, which feels kind of cherrypicked. If you go to ITER's website, it says:
"ITER will be the first fusion device to produce net energy. [i] Net Energy: When the total power produced during a fusion power pulse surpasses the thermal power injected to heat the plasma." https://www.iter.org/proj/inafewlines
What we see in Hossenfelder's video is spliced - the question and the answer are not related. The question is from Grayson's opening statement. The response is from a discussion between Bigot and Foster about heat flux to the diverter. Bigot's quote continues: "It is materials, okay. When we will have continuous production of plasma energies, with some energy flux with neutrons which are as large as 20 megawatt per square meter". They are talking about the energy in the plasma and how it will impact the diverter, not the overall efficiency of the plant.
My take was that the research had been captured by people motivated by writing papers, not by creating something that generates electricity.
I think that Fusion can be made to work in practice, provided the time/money is invested to solve the unforeseen technical and social (e.g., team incentives) problems. And yes, it is probably still many decades away.
I think there's a lot of daylight between a certain degree of salesmanship, of which I think it's fair to say Hossenfelder accuses the fusion leadership, and an actual fraud (which she does not). Just think of the muddle between Q_plasma and Q_tot as the fusion equivalent of Tesla's "Full Self Driving."
There's still a serious issue here. ITER costs a crap-ton of money and time, and necessairly that means any *other* approach gets a little starved of oxygen. It's reasonable to be worried that this is not the right choice, although that has to be set against the possibility that there *is* no good choice that doesn't involved enormous piles of money and decades of labor. Reasonable men can easily disagree on the better way forward.
Not sure Tesla FSD is a good example - that one may well end up in litigation. Wouldn't be at all surprising if it did at least; selling features you can't actually provide will eventually get the courts involved. See: Elizabeth Holmes. And there are sure a lot of people upset with Musk lately.
The issue here is more that, once again, we find scientists making flatly misleading statements to government and the public and then hiding behind "oh you just don't understand our technical language". I'm getting real tired of this. It's reminiscent of the way that the word "unvaccinated" doesn't mean to Pfizer/public health what it means to everyone else, or how "record breaking temperature" also doesn't have the definition you'd expect when coming from climatologists. The public will learn to stop trusting scientists thanks to this kind of practice. Arguably that's already happening.
There's a simple fix: fusion researchers need to stop talking about break even as a concept. Being extremely generous and assuming it's not deliberate, their own project leaders are sufficiently poor communicators that they keep misleading the public about what "break even" means. Even the definition of "engineering break even" is pretty useless: nobody would describe a machine as break-even if it generates more electricity than it uses but requires fuel only found on Jupiter.
Precise definitions of terms, and a carefully nuanced reporting takes a big backseat to "Fusion Real Soon Now! Rejoice!" or "Fusion: Giant Deplorable/Woke Fraud! Be Outraged!" in terms of page clicks, and those sweet sweet advertising dollars.
Secondly, people go *into* science in no small part because they don't *like* dealing with people, and aren't skilled wordsmiths, highly attuned to the implications and overtones their audience might take away. The stereotype of the scientist as a clueless one-dimensional dweeb who may fully grok quantum chromodynamics but gets tongue-tied ordering a sandwich is based in reality -- people who can *do* science are almost never very good at *explaining* it. And the people who have PhDs and end up doing a lot of talking to the public with some success are often a bit further from the front lines and drifting further away with time -- and develop their *own* concerns that are distinct from (1) understanding the science perfectly and (2) reporting on it dispassionately -- like, how's my new career as a science communicate going? How many "likes" are my Youtube videos getting? If they end up working for government then it gets even worse, because then it's also (3) is this going to play well/poorly with my politician employer?
Third, stuff like fusion (as well as a lot of other high-energy physics) is so expensive and labor-intensive these days that it's only done in teams of hundreds, massive collaborations. Under those cirx you don't have line workers talking to the media, you have a professional manager and professional PR staff, and for *them* their salaries are *all* about this particular project. You can't realistically expect the Director of CERN to give an objective evaluation of whether the LHC is worth the cost, any more than you can expect the CEO of United to speak objectively on whether it's better to Fly the Friendly Skies or take Ryanair and save a buck.
What investors learn rapidly, but which seems to strangely escape the Wikipedia generation, is that high-quality information is NOT FREE. It's not even cheap, it's very, very expensive, because it represents significant time and effort from somebody who is well-informed and skilled in the field. You want high-quality reporting on some issue that falls within my professional expertise, I'm happy to sell it to you, but my consulting rates start at $300/hour. Would you sell your professional skilled time for peanuts, or give it away? I mean, maybe randonly every now and then, as it amuses you, but on a regular basis you've got to pay your mortgage and all you've got to trade for dollars is your expertise.
So if you consume free information, be aware that the *true* customer for the reporting is not you -- it's whoever is actually footing the bill -- and adjust your expectations and skepticisms accordingly. If you want first-class accurate information, be prepared to pay beacoup for it. It's pointless to get mad at people who are enmeshed in the same economic necessities as the rest of us, and responding to the same signals and forces.
Nah, Hossenfelder had good points but has now gone completely on the contrarian for contrarianism sake side. I used to follow her blog since 2013, i stopped some three years ago.
She's probably right on LHC successor but as an example her piece on Ligo and gravitational waves was bad faith nitpicking.
She definitely has gotten used to being a contrarian. And there is a place for contrarians in popular science.
Most of her videos are about cosmology or high energy physics. These fields have lots of people who communicate them to the public. Brian Greene and Michio Kaku come to mind. Having one contrarian among many popular scientists is often a good thing.
I don't know if she realizes how few popular plasma physicists there are. Her Youtube channel is much larger than ITER's (472K vs 63K subscribers), let alone Commonwealth's (1.7K). For a lot of her audience, this is the most they've ever thought about fusion. I don't like that the contrarian is the only voice a lot of people are hearing.
I agree that contrarianism has a place (boy, i am contrarian myself) but even in hep she is not the best critic around (i would say Peter Woit wins on that).
She nitpick something she doesn’t like (like the definition of Q in this case, or the way the LIGO experiment checked the electromagnetic counterpart) and blows it up beyond proportions to claim that the entire field is rotten. Between other problems, this also makes it impossible to make a good and fair criticism where needed.
Even at her best in hep, it's not like her criticism are particularly great. Naturalness in particle physics is definitely a failed paradigm and dissecting why it failed is crucial to move forward the field (and this is not being done by the community). However, I don't think her explanation for why it failed is correct, i much prefer Woit's argument (https://www.math.columbia.edu/~woit/wordpress/?p=12108), but admittedly that may be saying more about my biases.
Err, real science is all about nitpicking. If you're not nitpicking then you're not being rigorous, so if that's all you got for your assessment of her LIGO post, then it seems she proved her point.
On DT fusion, Hossenfelder's problem is she isn't contrary enough. The big problems with DT were identified 40 years ago by Lidsky (and Pfirsch and Schmitter); DT fusion reactors inevitably have horrendous volumetric power density, at least an order of magnitude worse than fission reactors. This issue has nothing to do with plasma physics and is not solved by high-Tc superconductors.
I have not yet read the first article. I have watched Hossenfelder's video.
Her main argument seems to be that she doesn't like how Q is defined and wants plasma physicists to define Q in a different way. Disliking someone's definitions is not enough to claim that an entire field is misinformation.
"In the technical literature, this quantity is normally not just called Q but more specifically Q-plasma. This is not the ratio of the entire energy that comes out of the fusion reactor over that which goes into the reactor, which we can call Q-total."
This is wrong. In the technical literature, Q is Q. Q-plasma and Q-total are terms that she invented in this video. I don't know of a single piece of peer review literature that uses her terminology.
> This is wrong. In the technical literature, Q is Q. Q-plasma and Q-total are terms that she invented in this video.
Yes, they are terms invented in this video to clarify what fusion researchers are actually talking about. They are talking about Q-plasma where we're actually interested in Q-total. That's exactly what she meant by this paragraph, so no, it's not "wrong", it's clarifying the confusion.
From a recent video session Elon did at All In Summit. Not claiming EM knows this stuff best, but he seems clearly interested in the topic and would have had access to the people who know about this, and he would be looking at this from a practical/commercial rather than just scientific demonstration perspective.
Elon Musk seems to have a cursory understanding of fusion, but hasn't looked into it in detail. Which is not surprising because we shouldn't expect him to be an expert about everything. He is both too optimistic and too pessimistic in different ways.
He says it's 100% technically possible because you just have to increase the scale. That's not how probabilities work: Would he take a million to one odds on that claim? Getting fusion is also not just an increase in scale. It's mostly an increase in scale, but whenever you make things bigger, there's a good chance that something will be different qualitatively too. This is why it's important to make progressively bigger experiments, instead of jumping from your first small prototype to a full scale reactor. Looking at the history of fusion, we have been surprised by both bad things (e.g. large turbulent transport) and good things (e.g. H mode) when we were just scaling things up. ITER and SPARC are designed for Q = 10 instead of Q = 5, so even if the experiment performs half as well as we think, it will still be good enough.
The rare fuel claim is interesting. Because it either means that he doesn't know about the tritium breeding blanket or it means that he thinks that it will never work. Tritium is very rare, but a fusion power plant should make all of its tritium on site out of lithium.
Transforming heat to electricity is done in most power plants today. I don't think it's a deal breaker.
Maintenance of the fusion reactor might be a serious problem. We don't know how much maintenance is needed until we have one running.
Putting these together, Musk thinks that fusion will cost an order of magnitude more than wind and solar. This is not outside the realm of possibility. But it's much too early to conclude that fusion will not be commercially viable.
Jassby's claims that magnetic confinement fusion (MCF) has stagnated for the last 25 years, while inertial confinement fusion (ICF) has progressed. I do not disagree: "There has been little progress towards a larger triple product since 2000." I think that this is about to change, while Jassby does not.
There is a simple reason why MCF has not progressed. In 1997, the best MCF experiment in the world was JET. In 2022, the best MCF experiment in the world is JET.
There's only so much we can do with JET's size and magnetic field strength. They could probably get up to Q = 1.5 if they really tried, but not the Q = 5 that you need for a power plant. Instead, JET has been focusing on other important goals like getting the walls right and increasing how long they maintain the plasma. As soon as we get a better experiment, we will get better results, whether it's SPARC or ITER.
It is true that computer simulations did not predict JET very well and underestimated the turbulent transport. Computational plasma physics is a lot better than it was in the 1990s, along with everything else involving computers.
Jassby makes a big distinction between beam-thermal versus thermonuclear fusion. I don't know of anyone else who cares about that distinction. His footnotes for it all point to papers he's authored by himself.
There isn't a physical difference between beam ions and plasma ions. An ion typically has to collide a few hundred times before it undergoes a fusion reaction. So by the time fusion occurs, the ions from the beam are thermalized and are indistinguishable from the ions originally in the plasma.
He also seems to use the terms to describe how the plasma is heated. When the plasma is mostly heated by the beam, then Q must be small, and when the plasma is mostly heated by fusion, then Q must be large, ... because that's the definition of Q. The causality is backward. "For a purely beam-thermal system, the maximum theoretical Q is limited to less than 2" should be "When Q is less than 2, the system must be primarily heated by the beam."
Tritium is very expensive. You don't want your reactor to have to import it.
Each fusion reaction consumes one tritium and produces one neutron. Each breeding reaction consumes one neutron and produces one tritium. It looks like, in order to sustain this, you'd need perfect efficiency, which is impossible.
Which is why we're also planning on including a neutron multiplier: beryllium.
Be + n -> 2 He + 2 n
This increases the number of neutrons, which allows the system to sustain itself with less then perfect efficiency.
Jassby does not think that SPARC is a game changer: "improving cost-effectiveness is surely a distraction for MCF research". I disagree. Cost effectiveness is important on its own. And it means that we can build more reactors faster. It won't take us 25 years to get the money together to build the next big experiment.
I agree that inertial confinement fusion has made a lot of progress recently: "Progress has been extremely rapid. They crossed Q=1 a few months ago."
The big challenge remaining for ICF is going from 1 shot per day to 1 shot per second. NIF is not trying to do this, because fusion isn't their main goal. Maybe Marvel or someone else will figure it out. I hope that they do ! But I suspect that this will be harder than getting fusion using a tokamak.
I didn't go into the details of particular current experiments like JET or particular subsystems like the tritium breeding blanket to keep the review from getting too long.
Sabine makes technically correct observations but they are generally less informative than the metrics she's criticizing due to scaling
ITER would have a Q-total of 1 with a Q-plasma of 10. But dial up the size and plasma powering so that the plasma has 80 MW of injected power instead of 50 MW and you increase power output by 5x as the reaction increasingly powers itself and you're talking about a net GW of electricity
There appears to be no commercial potential as it stands with ITER style tokamaks but last year a superconductor magnet was tested that doubles the magnetic strength. With current structural materials it should increase tokamak power by 10x for a given size, enabling commercial levels of power output that could be seen as possibly commercially relevant in price depending on developments
Basically at small experiment sizes the Q-total is overwhelmed by the facility size and at large sizes the relative information value of Q-total is overwhelmed by the rapid scaling potential. It's useful if you know things in some depth where if you don't I think Q-plasma is preferable
"Dialing up the size" poses its own significant engineering challenges. It's not at all trivial or obvious that it would be feasible anytime soon. I guess we'll see.
There isn't a founding book on fusion like there is for Georgism. And I probably didn't execute this strategy as well Lars Doucet did. But I'm getting to talk to a lot of people about fusion and some people here like it a lot, so that's a success.
Right, as you go up the intellectual prestige level of book reviews, the the reviews become less and less tied directly to the book. At the daily newspaper book column bottom, reviews are about what the book has to say. At the New York Review of Books level, the reviews tend to be more about what the reviewer, who is an expert in the field, has to say about the subject.
Yes, I think that's great. And there's a common genre of book review that does in fact review the book while doing this. This one was just a nice essay without really telling me much about the book other than that a plasma physicist thinks it's good and their parents think it's readable.
I have had a couple of looks through and I still can't figure out who the author of "The Future of Fusion" is, and now I'm stubbornly refusing to google it.
No thoughts on General Fusion or TAE? As an interested lay person, I like General Fusion's approach (Steam pistons! Liquid metal vortex!), and it seems like they've made substantial progress, recently settling on a site in the UK for a demonstration scale plant.
I'm in the Vancouver area so I hear about General Fusion all the time, but can never tell where they stand relative to others in making substantial progress.
I don't know a lot about either of their designs, so I don't want to make too strong of statements. But I'm skeptical.
General Fusion:
Compressing a plasma is really hard. NIF has spent more than a decade figuring it out. That being said, General Fusion's plasma is magnetized, so it doesn't need nearly as much compression as NIF.
The liquid metal vortex is made of lithium-lead. If the lead gets into the plasma, it will radiate out too much energy.
TAE:
They're using proton-boron fuel, which means that they need to make their plasma 10 times hotter and 10 times better confined than if they used DT.
Both of these companies have interesting designs for their experiments. I wouldn't be surprised if some variation of these designs could work. I don't think that they're particularly close to success, but maybe that's just because I don't know.
TAE has said they will licence their design for DT fusion if energy companies want to build them. However proton-boron seems so unlikely in a steady state configuration it feels reasonable to question their general assessments of their technology potential. I'd say the same about Marvel, we're basically counting on some radical laser developments though as far as I understand it's at least conceivable to do pulsed proton-boron with the effects of lasers that accelerate the target fuel so fast the energy transfer is non-thermal
I'd put General Fusion in the same boat as Marvel at least. They have good engineering advantages such as guaranteed excess tritium production and a fully liquid wall facing the fusion reaction
Despite Commonwealth Fusion System's top funding and reputation it appeared to me that their engineering problems were in need of a dramatic unknown advance to target a commercial electricity price so that the real medium term front runners were the Helions and General Fusions that need big luck in physics but could at least project commercially relevant prices. However it seems that has changed with a new simulation prediction that high power tokamaks will be able to double density or more, which could quadruple power. Now where you had a price per MWh of well over $100 for CFS ($260 for the original ARC proposal albeit not intended to be a commercially optimized configuration) vs Helion's $60 or lower it's now conceivable for tokamaks to be commercially relevant if there aren't major downside surprises for steady state high power plasmas
I don't think that Helion and General Fusion have an advantage over Commonwealth. Getting the physics right is usually a prerequisite for being able to estimate what the commercial electricity price will be. Helion's price estimates are a lot more made up than Commonwealth's.
General Fusion might be in the same boat as Marvel. I put Marvel higher because progress at NIF has been much better than I expected over the last 2 years. Using the wrong fuel is still a major problem for Marvel - if they succeed, I expect that will change their mind and use DT instead. General Fusion doesn't have a big national lab doing something similar to learn from.
Do you think that TAE needs to be aneutronic to make the geometry of their machine work, i.e., is it simply impossible to put an effective blanket around a colliding FRC machine, or are they merely pushing p-B11 because it's sexy?
I'd also like to hear your opinion on MagLIF. To me, it seems by far the most rational of the magnetized target experiments, and they seem to be making steady progress and have scaling that isn't obviously insane. Also, given the fact that it's a Sandia Z-Machine experiment, they get a fair amount of money for doing something that could eventually provide cheap fast neutrons for [CLASSIFIED] at a fraction the price that NIF requires.
I think that a long term play of p-B11 fusion a-la TAE might make sense if they can conjure up some fancy physics (read, non-Maxwellian) to minimize radiative losses.
There seems to be a lot of negativity around this subject. My understudying is the science of this is accepted. It will work. The great difficulty is the engineering. This will be by far mankind’s greatest engineering challenge.
A lot of people will be upset if engineers solve this problem and the world continues on in energy abundance. How can we have Mad Max or some other dystopian future if engineers solve all the problems? Mankind must suffer!
"De-growthers" are environmentalists who believe we need to reduce the economy and energy usage in general in order to preserve or restore the environment. They would be strongly opposed to cheap clean energy because of the "cheap" part: if it's cheap, then people will use it to make more stuff, mine more stuff, build more building, have more babies, etc. Which (they believe) will put more strain on the environment.
So some people would mind. Your average person, of course, would be very happy. But then again, the average person doesn't think life would be better if we had 1/10th the population and most people were farmers again.
Tbf, the argument that economic growth will make people have more babies has been empirically falsified and we can expect fertility rates to go down as GDP goes up. While the rates of mental ilnesses in us youngsters grows.
Which is the reason why I am a de-growther despite not being an environmentalist.
Energy abundance, and if you believe that, dear people, let me share with you this brown glass bottle full of amazing cure-all that will fix what ails you.
I'm old enough that I've been hearing about "this one weird trick will give us all energy abundance", be it nuclear power (electricity too cheap to meter!), solar power, and of course fusion.
Fusion is interesting science to research, and a clever trick if you can pull off the engineering. In twenty years time, it will still be interesting research on plasma, and clever engineering tricks to handle plasma. It will never be energy abundance for all. And no conspiracy theories about mysterious They who will be upset if engineers solve the problem will change my mind on that.
It doesn't matter whether you are right or wrong, because this isn't the correct way to respond to somebody either way; it is unkind and unnecessary, given that there are kind alternative ways of expressing the same general idea.
(2) Kindly learn to distinguish rhetorical hyperbole from actual claims; why do you think I put the "magical technology" bit in inverted commas?
(3) I am not questioning the science qua science, I don't have the expertise to do so. The timeline sketched out seems very optimistic, but who knows?
(4) What I *am* questioning is the starry-eyed extrapolation to how this will change the world. We've seen plenty of promises of huge world-altering changes, and how many of them worked out the way they were intended? Fusion may well be a solved technology and we never adopt it on a large scale because by 2040 we have something else we're using. Please untwist your knickers about someone wondering if this time, this big promise is going to end up just like all the other ones.
Yes, _lots_ of things don't make it off the drawing board, and _lots_ of things don't make it past the prototype stage but, depending on how tightly you want to define "world-altering", there are at least dozens, and probably hundreds, of technical innovations that worked.
There is a reason to be more optimistic than this, because there's a new, mature technology that changes the game substantially: high-temperature superconductors.
More specifically, rare-earth barium copper-oxide (REBCO) tape is available commercially from several vendors, and it gives you roughly double the field strength at liquid-hydrogen or -neon temperatures instead of the liquid-helium temperatures required by ITER's magnets. This makes the magnets cheaper to build and operate, and allows the machine itself to be about 25% the size of ITER, which makes it much, much cheaper.
It's a game-changer. It's not a slam-dunk game-changer, but it's enough of one that the traditional "fusion is the power of the future and always will be" joke is now way closer to glib than it is to profound.
That said, there are plenty of things that can go wrong. The most important of those things is that SPARC, the reactor that Commonwealth is building, is still an experiment. It's not designed to be a commercially viable system. Indeed, they've made an interesting choice to trade machine life for earlier operation. So if they really do get to Q=10-20, then there's still a whole bunch of engineering to do to get to ARC, the machine that could be at the heart of an economically viable power plant.
I see you're also using the "by the time fusion arrives, what we're using for capacity will be a done deal" argument. But that argument is only true if you expect renewables to replace fossil fuels and then grow at a very sedate pace from there on.
I doubt that's going to be what future demand looks like. Indeed, I suspect that the successful mitigation and remediation of climate change will require expending energy in profligate amounts. Want to do atmospheric carbon capture at high scale? It's a massive power hog. How 'bout desalinating and lifting enough water to support agriculture in the Punjab--or Nebraska? What if you need to refrigerate the bottom of a glacier to prevent teratonnes of ice from sliding into the sea?
I'd like to plan on the world needing one or two orders of magnitude more capacity than dumb extrapolation would indicate. That requires another old cliché from the early nuclear age: power too cheap to meter. Maybe renewables get you there. But I want a few hedges against that. Fusion needs to be one of them, and it needs to be funded aggressively enough that it's not a joke.
I disagree. Deiseach's comment was sufficiently snarky and devoid of substantial arguments to invite a response like BronxZooCobra's. At least the latter actually included an example in which scientific and engineering progress, paired with political will, fixed a real, serious, global problem.
"At its core you don’t want it to happen because it will upset your worldview."
Come back to me when you get out of nappies, kid. I've been to this dance before, and it's never worked out like the techno-optimists have promised us it was going to work out.
Given that I am *constantly* scrabbling about looking for cheaper utility plans because the centres where I work *eat* electricity to run and we're on a tight budget, I would fucking *love* if somebody gave us cheap, clean, abundant energy.
You know what happened the last time there was a great plan to do this? Solar panels on the roofs of the buildings (including the building where one of our centres is located) in a new build project, to help cut down on heating costs because instead of oil and electricity, water would be heated by solar power.
You know how it worked out? Awful. First, this is Ireland - we don't get enough sun reliably throughout the year to generate enough solar power to boil a cup of tea. Second, when we got freak sunny conditions, it was *too* sunny and the panels exploded and had to be replaced.
So the "here's a cheap, clean, efficient energy source" green wishful thinking that was funded and built in all sincerity was a dismal mess. I have no reason to think fusion is going to be the one time there is never a problem and we all end up with our own personal jetpacks to fly us to the lunar tourist resorts.
“ I've been to this dance before, and it's never worked out like the techno-optimists have promised us it was going to work out.”
It hasn’t? It’s 94 in Houston and for almost everyone it’s 72. For hundreds of years the biggest killer was Tuberculosis. When was the last time you heard of someone dying of TB? For hundreds of year one of the great toils of women was laundry - girls used to not go to school on Monday’s as that was laundry day. They would spend the day at grueling backbreaking labor.
I just threw a load in earlier today and it’s done.
"Tuberculosis is preventable and curable, and yet 9 900 000 people fell ill with the disease in 2020 and 1.5 million died. This episode is looking at what the EU is doing to curb the spread and improve our understanding of the nature of the illness."
So yes, baby boy, people in this the 21st century *are* still dying of TB. Don't teach your grandmother to suck eggs.
So no matter what great advancements are made you’ll be a naysayer. Is that fair to say?
If I mention that Ireland has gone from one of the poorest countries in Europe to one of the richest you’ll bring up every negative you can think of rather than celebrating that great triumph.
And obviously I meant dying of TB in a first world country like Ireland.
And that you’re trying to argue that tremendous medical advances haven’t been made…
What's with all the ad hominem? From my outsider's perspective it looks like you're being very condescending and smug here. You can make your point without constantly calling someone a baby.
I think that laundry story is a myth. Laundry was much difficult in the past therefore we did much less of it. Today we spend the same about of time on it because we wash every piece of cloth everyday. This partially confirmed by my childhood experience when I lived in frugal conditions (ex-Soviet country), sometimes even without electricity and washing machine.
Indeed people would wear clothes many many more times before washing them. It absolutely was a huge chore, but people weren't spending 8 hours a week doing laundry.
“ it's never worked out like the techno-optimists have promised us it was going to work out.”
He says via a system of electrical impulses that are converted to pulses of light that flash along hair thin strands of glass under the ocean to propagate his thoughts to thousands of people around the world.
Technology is wonderful. Human nature, however, doesn't change. Impress me with your shiny space colony fusion future when the people inhabiting it aren't bitching about so-and-so has nicer quarters, better rations, or access to fifty-seven genders as social identities and I'm confined to only forty-six.
"Impress me with your shiny space colony fusion future when the people..."
That, by the way, is why I don't think space colonies are feasible until they are governed by an AI, and we have a vastly improved sociology. And probably also a vastly improved virtual reality. Until then we'll need to have small groups with strong bonds holding them to the home planet. And I still think that's what we should be aiming for.
OK, but you need to be aware that nobody predicted that years in advance. They predicted other things that didn't happen. Predictions in a complex area are almost always wrong, and when it's got chaotic resonances and strange attractors...well, the predictions are often WILDLY off, even if many of the details are correct. E.g. read "True Names" by Vernor Vinge. (That may have inspired the Matrix movies, but that's a guess.) Now compare it to on-line chat groups and other similar phenomena.
Is there any substance to this comment beyond "this will never happen because it would be too good"?
Besides, the examples you cite are not actually terribly supportive of your point. Nuclear energy didn't give us energy abundance essentially because we decided not to build it. Solar energy is _currently_ growing and getting cheaper at astonishing rates, such that the main obstacle now is storing and transporting it, not generating it.
"Nuclear energy didn't give us energy abundance essentially because we decided not to build it. Solar energy is _currently_ growing and getting cheaper at astonishing rates, such that the main obstacle now is storing and transporting it, not generating it."
You have answered your own question. Right now, fusion is at the "it will be fantastic magic out of nothing clean cheap infinite energy!" hype stage (and has been since the 70s and possibly before, but I can't remember anything before then).
Nuclear power was going to be the same - and then, as you said, we decided not to build it.
Solar/renewables were going to be the same - and then we ran into "crap, we can generate it but can't store it for even and sufficient supply".
Why do *you* expect the development of fusion will run any smoother and without obstacles bobbling up? As to "there are a lot of people who will get upset if we get cheap clean abundant energy", does anyone else get the "we have the technology to let cars run on water but Big Oil is suppressing it" vibes?
>You have answered your own question. Right now, fusion is at the "it will be fantastic magic out of nothing clean cheap infinite energy!"
Describing fusion as being based on "magic" is bad faith. You're unfairly trying to make them seem unreasonable by using BS terms to describe their claims.
>Nuclear power was going to be the same - and then, as you said, we decided not to build it.
Because it was too expensive to build it to be safe enough. Unless similar safety issues requiring very expensive engineering controls will be present for fusion reactors, then fission being too expensive to build is completely irrelevant to fusion's potential.
>Solar/renewables were going to be the same - and then we ran into "crap, we can generate it but can't store it for even and sufficient supply".
Again, unless this describes a problem that fusion will also suffer from, IT'S IRRELEVANT.
>Why do *you* expect the development of fusion will run any smoother and without obstacles bobbling up?
Because the issues with other power sources are not conceivably an issue for fusion. The burden of proof is on YOU to demonstrate that problems will likely exist. Otherwise, no new technology ever has any hope of working because something completely different in the past didn't work.
Not sure about some of that. Fusion certainly has the potential for radioactivity problems like those that plague fission power -- anything that generates MeV neutrons is going to have *that* and fusion neutrons are even more energetic than fission neutrons. We don't know yet what those problems will be, and how easy/hard they will be to solve, because nobody has yet built a practical fusion reactor. But they aren't simply absent because of the technology.
>Because it was too expensive to build it to be safe enough.
What killed it was the ALARA standard, which defines "safe enough" as "maximum safety possible at the same price as existing power stations" and therefore "enough spent on safety that it's not worth building". Sane definitions of "safe enough" (e.g. "safer than coal") weren't too expensive at all.
"Sane definitions of "safe enough" (e.g. "safer than coal") weren't too expensive at all."
If a coal mine in Cumbria catches fire, that does not affect me. If Windscale/Sellafield goes ka-blooey, that does affect me (based on what way the wind is blowing) and I don't even get the benefit of the power it generates. "Nuclear power plant goes up in flames" is a hell of a lot more dangerous than "underground coal fire".
I don't expect that commercial deployment of fusion will be rapid and unhindered. In fact, I'm not even a fusion partisan - I don't know whether it'll work or not. What I'm taking issue with is you staking out the position "this definitely won't work well enough to cause dramatic improvements" and basing it on some combo of "we haven't had something this good happen yet" and "there will be issues to deal with along the way".
Those claims, though true, aren't a meaningful argument about whether fusion will have a major impact because they apply equally well to any energy source you could imagine. Unless there's some iron law of nature that applies, arguments that treat the particular facts as irrelevant details are insubstantial.
I am with you on this. Fusion energy might work but the social aspect will not be simple.
I compare this with covid vaccinations. We were not sure if the vaccine will work, but then it worked. Not perfectly but reducing risk of death about 10 times was great and we should have returned to pre-covid society in about March-April 2021 when the elderly population was vaccinated.
It didn't happen for some reason. It wouldn't have happened even if the vaccine was 95-99% effective and sterilizing. Politicians would still obsess with restrictions because the risk was not 100% eliminated and so on.
We are unhappy society not because we don't have abundant clean energy such as fusion. Fusion is an interesting scientific/engineering problem but the issues we deal with is only 5% about the lack of clean energy.
Actually, I'd but the issues at over 50% due to a lack of abundant clean energy, but that would be soluble. It would be expensive, but we know several ways to handle it. We could even do it with giant mirrors in the desert that melt special salts that we then use as an energy store. So lack of a way to deal with it is not the basic problem. There doesn't seem to be a willingness to deal with them, because doing so would require small short-term sacrifices to ensure long-term flourishing. But people over-discount the future. (And, truthfully, often the people who benefited would not be the ones making the sacrifice.)
I think the reason we are not building those giant mirrors in desert that the society (some rationalist geeks excluding) don't think it needs them.
I personally think that would be a cool thing but the problem is to sell the idea to others, especially policy makers. We need good story tellers, really good ones in fact. I think that's why I like Scott. He is a geek who can also tell stories.
If[1] fusion works, I'm sure some people will object to it enough to stop it in their communities. But unless they can stop it everywhere, including China, the future is still coming.
It depends on specific details with the new technology – cost, environmental impact etc.
Right now I hear a lot of arguments from greens that nuclear power is bad not because of radiation but because it costs too much and is not profitable. Wind and solar is much cheaper and don't need to develop anything else. The countra-argument that we need to ensure base-load is hard to make because it is hard to wrap in a good story.
Nuclear fission didn't yield energy abundance because the downsides to building it were too high. The goal was never *just* energy abundance. People assumed that there wouldn't be huge downsides. It's also quite expensive to run the (current) plants in a way approximating safety.
OTOH, I've read SF from the late 1930's and early 1940's. When they assumed that energy abundance was feasible, they didn't assume that this would lead to anything even approaching idylic lifestyles. Often they assumed to opposite, though you didn't get things like Heinlein's "Blowups happen" until after the end of the war. But if you were getting "energy abundance" and "energy too cheap to meter", you are/were believing PR puff pieces. (Most of them by companies trying to ensure continued government funding.)
Heinlein's "Blowups Happen" is a short story from the 1940s about the boss of a nuclear power plant going insane from the high risk.
In general, golden age science fiction authors tended to assume that disasters would happen (e.g., in Heinlein stories there are usually unexplained references to "New Chicago" or the like, leaving it up to your imagination what horrible thing happened to old Chicago). They tended to assume the public would keep the same appetite for risk-reward tradeoffs, not realizing that people would become more safety conscious (e.g., swimming pools used to generally have diving boards but they don't anymore).
The one area where elites haven't got much more safety conscious is advocacy of bicycle riding, which is popular to encourage despite it becoming relatively more dangerous over the course of my lifetime as others things have become safer.
I'd be interested in why ITER is in France. I'm guessing it's related to why France relies so much on nuclear power: because France has an old fashioned modernist powerful centralized state without all the local checks that, say, California has that slows down construction by adding a whole bunch of levels of veto.
"Blowups Happen" assumed there wasn't any way to make the power plants safe. So much so that the only answer was to put them in orbit. When you say "Golden Age" I'm not sure whether you mean pre-war or post-war, but after Hiroshima the mood was very different. Heinlein started to move away from advocating nuclear power ("Life-line") and Poul Anderson wrote "Tomorrow's Children" to name just two.
> Is there any substance to this comment beyond "this will never happen because it would be too good"?
It's not that fusion won't happen because it would be too good, it's that even if it does happen it won't be as good as you think. Fusion won't be the free energy panacea everyone seems to be selling.
This is literally not an argument. There's no substance to it whatsoever.
Fusion is categorically different to fission. The fact that fission has not lead to energy abundance is irrelevant. The reason fission is so expensive is the engineering required to make it (excessively) safe. Fusion is not dangerous in the way the fission is, and so this cannot be the economic failure mode for fusion.
There are very clear arguments for why fusion will/could/should lead to energy abundance. If you're unwilling to engage with them, you shouldn't be making a post against them.
People have made bold claims about energy abundance before - this is irrelevant. Fusion is very different to these things, so simple minded appeals to analogy are not valid. If you have a *specific* reason for why fusion won't lead to energy abundance, fine, make it. But this comment is exactly identical in spirit to declaring that heavier than air flight can never work, because look at the thousands of failed attempts in the past.
I'm seeing a lot of "wah-wah-wahing" for my refusal to accept "but *my* technology is different!"
I hope I can make you understand - all the arguments you are pooh-poohing right now ('well, fusion was *never* gonna be at the races') are *precisely the terms in which the fusion argument is being presented*.
Fusion will/could/should lead to energy abundance? Heard that before about nuclear. Now you are telling me fission is *completely* different (which I accept on a physical level, yes it is) and that is why it never fulfilled all those promises. But fusion is going to do it.
Look, I can't speak to when fusion is going to be a solved problem. It may well happen by 2040 or 2050. But Shiny New Abundance World? Merely solving the technical aspects is not going to bring that about, which is what I am trying to point out. We *have* experience of "as soon as we get the bugs worked out, this will solve all our energy needs!"
And has it happened like that? Are electric cars solving the problem of gas prices going up and people being discontented for the midterms? Are we zooming around to our lunar resorts? Yes, I'm pouring cold water on the Shiny New SF Future.
I would love to have it. I *want* the Shiny New SF Future I was promised as a kid in the 70s. So much of the far-flung era of the 21st Century was going to be way different because Science!
And now we're back to 70s stagflation, price increases at the petrol pumps, and you lot in the USA can't even feed your babies due to a shortage of baby formula. And we have Russia in another war of aggression.
Tell me how "this time it's different" and I'm a science denier. I'm not denying the science, I'm denying the social and political extrapolation from it. "If we solve fusion we will get cheap abundant energy". Maybe. And maybe not. I asked why countries didn't engage in fusion research, and got told "Oh well, maybe the Cold War?"
If we're going to be demanding specific reasons, I want a better one than "fusion scientists were too pure-minded to engage in politicking". Maybe countries didn't pour money into it because the game wasn't worth the candle.
And don't try and convince me that past bold claims about energy abundance before are irrelevant, when you are using the same pitch to persuade me that this time, there *is* a pig in that poke.
Try zooming out a little bit. Capitalism and technology have, in fact, solved all the world's problems if you take a longer time frame and look at the right metrics.
Sure, but if that argument is highly persuasive, then it suggests things like ITER are folly. We should just let capitalism and technology solve the problem of the most efficient energy generation scheme, and stop trying to use government to force one particular solution.
Why limit our options? The public sector and the private sector should *both* be working on this. If success comes about through the free market, great. If success comes about through the state, also great. Yes, too much government spending can disrupt the market and reduce its overall efficiency, but ITER spending is just a few hundred million per year out of a $5 trillion budget - it's not going to tank the economy. The internet was developed through a mixture of public and private funding, and the same could very well end up being true for fusion.
Nuclear power has certainly been a disappointment—though it does produce a ton of clean energy and will for decades and decades—but if fusion fails as badly as solar power we *will* have energy abundance. Solar has gotten incredibly cheap and abundant over the last 20 years. You're also old enough that you will have heard stories about impending energy disaster for your entire life—peak oil, etc. Technological advances, not just in renewables but in energy efficiency and even the discovery and production of fossil fuels, have made that seem ridiculous over and over.
To be clear I don't think there's any "mysterious They" keeping us from fusion, though it certainly seems like we should have been spending more given the potential rewards. But the idea that we haven't solved a bunch of big problems since you were young is simply not true, so it's not a good heuristic for deciding whether some future technology is plausible.
I'm a car guy, and future-energy stuff makes me think about cars anyway, so for example (and I know you're not from the US, but those are the stats I know)—in 1969, when we landed on the moon and before standup comedians could conceive of asking where our flying cars were, 5.19 people died per 100 million vehicle miles traveled in America. In 1987, when I was born, that was 2.42. In 2021, that was 1.33. At the same time cars have become more fuel efficient, dramatically faster, etc.
Likewise, in my dad's lifetime (1948-) we've gotten "too cheap to meter" wrong, and he always kids me about it because he knows I love reading about nuclear power. But we've also basically wiped out polio (2000 US deaths the year he was born), measles (400 or so), and rubella (last epidemic in 1964-5 apparently caused 11,000 fetal deaths and 2100 neonatal deaths). Even COVID—we certainly could have done much better, I think, with better trial processes, and the death toll has been awful. But also, within a few months of the first community spread of COVID in my area I was in a trial receiving what turned out to be an extremely effective vaccine for it. That's incredible! And people who held themselves out as a realistic level-headed experts *at the time* were saying that it was going to take twice as long, or three times as long, or more.
I know none of this is news to you, obviously, but I just don't see how the last 40 years would make you think "energy too cheap to meter" is a uniquely impossible dream to achieve.
I think we all believe in progress, but progress per se is not a good argument for the odds of success of any particular technological push -- not when history is absolutely littered with the corpses of technological pushes that failed.
Yes, human beings will probably continue to advance technologically for quite a while. But will that progress be represented by achieving practical fusion power generation? Maybe, maybe not. Progress isn't uniform. We tend to make breakthroughs in random areas, hard to predict[1], and advance amazingly in one direction while not much else happens in others. Maybe progress in this century will be amazing in fusion, or maybe it will be in some other area -- maybe someone will produce an effective vaccine against breast or prostate cancer, and a terrible scourge will be vanquished, and then arguments in the future will be like "we beat breast cancer, isn't that amazing? so why don't you believe we can develop a warp drive/fusion power/some other techno miracle?"
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[1] A cautionary tale here is the fact, mentioned in the review, that high-Tc superconductors were a game-changer for fusion. But nobody was doing research into superconductors *as part of* fusion research, because nobody had an idea that much higher Tc could be achieved at all. It was a surprise. But that's kind of how science works. A lot of time, the key advances you need happen in fields you didn't expect, and so it's hard to plan for them and *especially* hard to put them into a budget and deliberately create them on a schedule as part of a "throw money at the problem until it's solved" approach.
To be fair, though, while fusion is likely a pipe-dream and so is limitless energy in general, I don't believe that mere energy abundance is an impossible goal. It might not be achieved via fusion, but it can be reached via a combination of various technologies, such as solar, wind, tidal, geothermal, and of course nuclear. We have all of these technologies today, we just need to invest in them -- or, in case of nuclear power, stop banning them. There are also productive engineering projects to be developed, such as improved nuclear reactors and orbital solar collectors.
The major problem with all of these is that it would require a massive investment a la the Manhattan Project to significantly improve energy availability... and I do not believe that any Western country has the ability to do that anymore. China has the ability, but not the desire -- they're fine with coal.
I suspect the issue is overloaded definitions of "energy abundance". Some hear that and imagine you are proposing "post-scarcity".
Suppose we get energy abundance, the price of electricity drops to 1/1000 th of current rates (or lower), everyone has an electric car that doubles as a portable battery.
No doubt we will find some amazingly wasteful ways to use energy, and then face bunch some other limits (battery material precursors become expensive, ditto for conductor metals for the distribution to end-users, or maybe there will problems in scaling the ability to reprocess used batteries to match the production [1], some environmentalists are bound to oppose solar and wind farms, ultimately there could be issues with dumping all the excess heat from all the appliances everyone is running). The energy abundance might happen, but it is a real possibility it won't be an experience of plenty ... any more than our current way of life is.
What we did with the abundance of compute cycles? Price of MHz has gone way down since the first microcomputers. The Allies had years of money and person-hours in compute effort to crack the German military codes. Today probably you could have a novelty screensaver to do it. But does it feel like in post-scarcity compute utopia?
Everyone has a smartphone and spends a lot of time on internet. Yet the high-end computing experiences are still very expensive. If you can get a VR headset, you are certainly above median income. If you can finance (out of your own pocket) enough TPU hours to train a custom GPT-4-sized language model to produce the best AGI memes for your personal fun, you are certainly a millionaire.
[1] Think of the 19th century fear of "peak horse manure" problem.
There will never be "abundance" in the sense of "too cheap to meter" - there are just so many things you can do with large amounts of energy that the cheaper energy gets, the more we will demand, and we will always be operating at the frontier.
However, it does seem likely that there may well be "abundance" in the sense of a return to the growth rates of energy use comparable to those of the 1950s and 1960s. In the 1970s, there was a slowdown in overall energy use growth (along with a million other things) as the oil crisis hit. Since around 2000, total energy use has stagnated, as coal and oil started being phased out for gas and renewable. Even without fusion, if renewables can continue their exponential growth after coal is done phasing out, then we already get substantial energy growth until gas starts phasing out. With fusion, there's a good chance that continues even with gas phasing out.
I don’t recall why likes aren’t allowed. It seems valuable to poll the commentariat as to the validity of a given argument. Our host is a fan of prediction markets. Maybe we can pay per like? It’s not a true prediction market but we can say “I really think this is true.” And $.05 goes to our hosts favored effective altruism.
That's a fun idea, but he's using the Substack platform, and since this doesn't sound like an idea that many other Substacks would want to use, they might not want to go through the work of implementing it.
When I was age eight in 1967, 55 years ago, the L.A. Times began running a Sunday comic strip about science. It's first ever topic was "Fusion Energy Is Coming."
Do you think the idea of the cost of electricity going down by a factor of, say, 20 is more implausible than the transition from not having electricity at all to having it in the first place? If so, why?
What exactly do you mean by "the cost of electricity going down by a factor of 20"? Do you mean "cost of generation" or "total cost of your electricity bill at the end of the month/bimonthly billing period"?
Because I could see costs of generation going down, which of course is going to have an effect on the total of the bill. But costs of generation alone are not all that comprises a bill. I don't know how American bills are calculated, but here's a sample of an Irish bill - and please note, there is a temporary reduction of VAT from 13.5% to 9%:
Under the old VAT rate of 13.5%, the total cost of this bill would be €149.43
Cost of electricity at €0.258 unit price (and that's not a standard price, it depends on your tariff) less discount = €78.61
Cost of add-ons (Standing Charge, PSO levy, and 13.5% VAT) = €70.82
Total bill: €149.43
Suppose cost of electricity plummeted to €0.052 unit price, the new bill would be:
Cost of electricity = €17.32
Cost of add-ons = €55.39
Total bill: €72.71
That is a great reduction, but as you can see, the greater part of the bill is still not the electricity cost as such. And depending on the running costs of the fusion plant and costs of getting the generated electric into the grid, etc., the add-ons might even be increased to cover the cost.
So "cost of generating power via fusion drops", sure. But maybe "cost of building, paying off debt on building, return of profits to investors and shareholders of fusion plant + other extras rises", as well.
IMO mankind's biggest problem right now (aside from our own human nature) can't be solved by energy abundance. The issue is that we're fouling our own nest, and making the planet unlivable. Sure, it'll help if we stop burning so much fossil fuel, but that's not the only thing changing the climate and killing off the biosphere.
There's a hell of a lot we could do with abundant energy to make things better. You also haven't described 'the biggest problem', you've described hundreds of smaller problems and lumped them all together. There's nothing that can solve all of these problems simulteaneously, so the fact that fusion powered energy abundance can't solve them is irrelevant.
"Sure, it'll help if we stop burning so much fossil fuel, but that's not the only thing changing the climate and killing off the biosphere."
It's not the only thing, but an abundance of cheap energy could easily help to mitigate a lot of the other problems too. Energy can be used to get rid of waste, after all. Energy can also be used to make all sorts of processes (not just energy generation) more efficient so that they generate far less waste to begin with.
"Things that could theoretically be done with electricity instead of fossil fuels" covers probably 80-90% of greenhouse gas emissions - that's not a small change. And the industries that can't directly be replaced by electricity (e.g., livestock emissions) can still be handled in principle by throwing energy at carbon capture projects.
Lab-grown meat is energy intensive. I think they'll get there if they're willing to use real animal meat as necessary to complete the jump over the uncanny valley, but the animal footprint could be reduced by an order of magnitude.
I don't actually think that people will be upset if many of our problems are solved by technology. I think that a lot of people just see problems that stem from political/societal issues (e.g. global warming would be eminently solvable if governments cared and would coordinate, but because they don't/won't, it's a huge mess) and feel intuitively that they have to be solved through political/societal battles. It's actually kind of tough to have the intuition that instead of winning or losing a fight about those issues, we may just stop needing to fight due to quantitative improvements!
While it's about fission, not fusion, I think this New Atlantis piece explains fairly well why laypeople are disinclined to trust "the science" when they distrust the mediators implementing the science:
In the abstract, I'm irritatingly techno-optimistic! But I've also accumulated enough bad encounters with the gatekeepers of all this wonderful, life-enhancing technology to find myself, rather against my will, growing increasingly distrustful that it will benefit "people like me" when "we" need it.
Take, for example, the humble X-ray. X-rays are amazing! Sometimes they've benefited me. But they've also been used to justify denying me timely care, needlessly harming assorted body parts. I know the X-rays themselves weren't to blame. The problems were with human judgment: X-ray being the wrong tool to rule out a likely problem; wishful thinking in interpreting X-rays to avoid the liability of treating someone pregnant... I didn't have unmediated access to X-rays' diagnostic power, but access mediated by someone whose job it was to know better than I how to use this wonderful technology, and who, for whatever reason, didn't do the job promised.
Reassurance that fission *can* be made safe doesn't necessarily inspire trust that it *will* be made safe if a fission plant is built in your neighborhood. Technical reasons for fusion plants to be more feasible still wouldn't address various social and political aspects of feasibility.
Supposing we did build a fusion-fired power plant, would people worry about it exploding like a giant boiler if something got clogged, "taking out the neighborhood"? I don't know that it would "take out the neighborhood", but steam explosions still kill people, and steam driven by what could be summarized as an artificial sun does sound extra-feisty. Even if laypeople were persuaded that fusion isn't the same radioactive danger fission is, would they trust the whole apparatus, steam and all, to be sited and maintained properly so that they're not the ones "punished" by a fusion plant going "boom"?
Can laypeople trust whoever's in charge to use technology appropriately around them?
It is safe. It’s incredibly safe. It’s only not safe if (among other things) you discount the lives of every coal miner who died of black lung. And that’s just for starters.
I don't discount those lives. Or the other stuff you allude to. I'm pro-nuclear-power. Grateful to live in a world where it's possible.
I'm also pro-X-ray. I've nonetheless accumulated experience suggesting I can't trust X-ray diagnostics to be used correctly on me. I still chalk that up to "random bad luck" or "maybe I *am* that poor of a patient advocate for myself." But it gives me more sympathy for someone in a LULU (locally unwanted land use) neighborhood who hears, guess what?! Our LULUhood's the lucky winner of the new fission plant! We're reassured that, all around the world, fission plants chug along safely and cleanly (which, yes, they overwhelmingly do), so *of course* the one planned for neighborhood will... even if previous LULUs didn't turn out so well for us.
As I understand it, a lot must go right to ensure the fission plant design that's currently dominant runs safely. We have the technology to ensure it does go right! And usually the conscientiousness, too.
Yeh. But then I hear there are anti-wind turbine protests in Europe. Ok, you don’t want wind, you don’t want solar, you don’t want coal, you don’t want nuclear and you don’t want Russian gas, fine. You’ll just have to freeze to death in the dark come winter.
If by "you" you mean the impersonal "you", rather than me, specifically, I get what you're saying. If you mean me specifically, I moved to a LULU to get a better deal on housing.
Perception snaps into schemata based on experience. One schema is "modern technology has had phenomenal success saving and improving lives, including poor and powerless lives" (which is true!). Another is "LULUs are LULUs for a reason" — and in neighborhoods with a history of suffering due to LULUs, "others benefit from modernity by dumping its dangers here". I doubt which schema wins is entirely under people's conscious control.
"If it's so safe, why won't the ritzy neighborhoods take it?" invites the logical rejoinder, "Why waste money building it on such expensive property?" but it wouldn't surprise me if the example of wealthier, more powerful neighborhoods volunteering for these projects were more persuasive to holdouts than the fact of general gains through technology. YIMBY!
Actually the coal plant likely has significant health impacts on you because its emissions are incredibly harmful. Everywhere more coal plants open infant mortality rises, as does asthma, cardiovascular disease and a bunch of other things.
"We see massive differences in the death rates of nuclear and modern renewables compared to fossil fuels.
Nuclear energy, for example, results in 99.8% fewer deaths than brown coal; 99.7% fewer than coal; 99.6% fewer than oil; and 97.5% fewer than gas. Wind, solar and hydropower are more safe yet."
Like, it's scary something might blow up unexpectedly and kill you, but if we replaced all coal with nuclear total life expectancy would go up, disasters included. It's similar to comparing flying to driving. I'm not sure if you have any particular hangups there, but the argument is really similar. Flying is saver than road tripping to your destination. But people are afraid of flying because the rare air crashes are really bad and kill lots of people. But risk is likelihood multiplied by impact.
I dunno. If I take a look at my latest electricity bill, only 25% of the cost is listed as due to the cost of generation. 75% is distribution and taxes and bond payments and whatnot. So if fusion reduced the cost to generate electricity by a factor of 10 -- which seems darn optimistic -- then my electricity bill would be reduced by about 20%. That's not nothing, but it doesn't fall into the category of "enegy too cheap to meter" or some such.
I thought the main argument for why fusion power is nifty is that, like fission, we don't produce pollutant gases or have to pay for expensive scrubbing tech, don't produce a crapton of CO2, and don't have to stripmine Wyoming to get the fuel, but unlike fission we don't have as much high-level radioactive waste and don't worry so much about people building nuclear weapons with the same tech. These are all defensible goals, but they're not really related to the economics of power generation.
That’s a good point. The thought is that if energy is cheaper then concrete is cheaper, copper is cheaper, steel is cheaper, etc. If those things are cheaper, if the fundamental quanta of energy in our civilization is cheaper*, then vastly more things are possible.
A world with abundant energy would not have the same transmission costs as indicated by your current bill. A fusion civilization would not be on the same Kardashev scale as our current civilization .
Yes, I'm aware of economics. I'm just pointing out thatin tthe economic component (my electricity bill) that has the *highest* proportion of its cost going to generation, the amount isn't actually that high. The impact on the price of concrete or copper is necessarily going to be even less.
Anyway, I don't disagree that cheaper energy is better. Economic efficiency is always a win, except maybe cheaper high-quality cocaine, not sure that was a good thing when it happened a few decades ago.
I do think to be taken seriously one would need to make a good case for *why* fusion energy would be so very much cheaper than any other type. Where's the giant savings coming from? Not from simpler and cheaper to build power plants, clearly. Low fuel costs? I mean, maybe, water is cheap, but deuterium is not, although fortunately you need very little of it.
But the story of nuclear fission is cautionary: *that* turned out not to be cheap, despite the fuel costs being minimal. So one would have to make an argument why the entire generation cost, soup to nuts, fuel plus capital and operating costs of the physical plant, regulatory and cleanup costs, environmental costs, et cetera, all work out to be way way cheaper. Haven't seen that argument yet.
I don't really see why transmission costs would disappear. If anything, I would expect them to be higher. A fusion plant is *such* a complex and expensive piece of machinery that economies of scale would suggest you just build one or two for the entire United States, have them generate TW of power, and distribute it everywhere. That's how nukes worked out, after all: it turned out to be better to build a great big one, which could generate massive watts at a minimal $/watt ratio, and then pipe it around.
“ I do think to be taken seriously one would need to make a good case for *why* fusion energy would be so very much cheaper than any other type. ”
Scale - solar will never make getting you to orbit cheap. Fusion can. You can’t think in terms of your energy needs now, with current technology, you need to think of “your” energy needs 50 or 500 years from now.
Yes, scale is not a bad argument, but again we get back to the point that 3/4 of my energy bill *right now* is distribution, because we already kind of use scale in electricity generation -- that's why we have all these enormous towers and transmission lines going thousands of miles. So we need to understand why scale, which is already being used pretty heavily, hasn't at all reached the limits of its potential.
I'm not seeing how fusion helps me get to orbit cheap. The problem with getting to orbit is that I need to generate a lot of kinetic energy *but* I also need to generate it quickly (high thrust) *and* I need to generate it on board a flying vehicle (so the tragedy of the rocket equation). How does having gigawatts of electricity available for cheap on the ground help me out? Are you thinking some kind of railgun approach? I put all my kinetic energy into my orbital vehicle on the ground, then let it blaze (literally ha ha given friction in the lower atmosphere) to orbit?
Liquid hydrogen and oxygen are very effective and very expensive as a method to get you to orbit. If there was a technology where we could cheaply crack water and then condense the resulting components, that would be a big deal.
This is just a random example off the top of my head.
If you're going to claim fusion will get you to orbit cheap, you need to be more explicit. Perhaps you're thinking about a laser-powered first stage? I've seen speculative designs that don't look implausible, but also aren't really convincing. Or perhaps you're thinking about something else, but it sure isn't clear what. It won't give you a cable good enough for a space elevator.
Right. The obvious wrong answer, per many generations of science fiction, is that we're going to fly to orbit using fusion rockets or "drives" that are vastly more efficient than chemical rockets. And maybe in the 23rd century, we'll be doing that - but none of the fusion technologies discussed here are remotely practical for earth-to-orbit propulsion. The power-to-weight ratio is going to be far too low, and the power comes in the form of relatively low-grade heat in the neutron-absorbing blanket that is difficult to turn efficiently into rocket thrust.
Fusion-based systems may have some utility in deep space transportation, where very low but continuous thrust will suffice. That's actually part of Helion's backstory, among other things. But it won't get you off the ground.
And while you can envision using "too-cheap-to-meter" fusion power to run beamed-power propulsion systems, or electromagnetic launchers, or to turn water into liquid oxygen and hydrogen, that's solving the wrong problem. As others have noted, the *energy* costs of space launch are a tiny fraction of the total. It's hardware and operations costs that make space travel ridiculously expensive. If you come up with a system that works, you can get the power from the current grid just fine.
I don't think it's going to just be "10% off your electric bill"[1] but "there are a whole bunch of new ways we can use electricity that we didn't think of before." People who hauled water up from wells by hand would never consider daily showers or water parks.
Matt Yglesias has a bunch of articles at Slow Boring about energy abundance.
[1] I don't know off-hand what proportion of my electric bill goes to just the labor for maintaining the grid but it more than doubles during the summer months so I know it's not just 25%.
Well, we'll see. I'm still missing the part where electricity becomes fantastically cheaper because it's produced by fusion instead of fission, or burning nat gas, or even rooftop solar. The capital costs are admittedly enormous, the operating costs (skilled labor, upkeep and repair) look to be pretty darn expensive, at least as much as operating a fission plant, and we're looking at if anything higher distribution costs because it's inherently a lot more centralized than something like a nat gas plant -- we're going to need still more transmission lines and all the associate switching and load balancing hardware, which all needs its own upkeep. Nobody is going to be dotting the countryside with 150 million K operating temperature tokomaks which require the kind of precision and care in assembly that goes into a chip fab or fission reactor.
I get that water is very cheap, but tritium isn't, and it's a bad time to be competing on the world market for lithium (plus natural lithium is only about 5% Li-6 if memory serves, so you might need expensive isotope enrichment), so while you need very little of the fuel stuffs it doesn't feel any more economical than fission fuel.
As a technological achievement is seems extremely cool, and it would be good to have some more options for power generation, but I'm just not seeing how this is going to make electricity -- from start to finish, from funding the capital construction costs to delivering it to the end user -- just amazingly cheap. It feels a little uncomfortably like an Underpants Gnome theory of energy abundance:
1. Fusion breakeven achieved!
2. ????
3. Energy too cheap to meter, changes world.
I totally agree with (3) but it's (2) that has me a little skeptical. I hope the problems are solved, I'd love to live in a world like that, but...it would take more than I've heard to persuade me it's definitely on its way.
Engineering challenges go away if you throw enough money at them. The Manhattan Project was, primarily, an engineering challenge.
Materials challenges are potentially intractable because the material doesn't exist. You can throw all the money in the world at high critical temperature, high critical field superconductors, and still not wind up with any. Because they don't exist.
I just made this account so I can engage in the conversation, while still being an anonymous reviewer. I will try to answer all the questions I find in the comments.
I have invited Jason Parisi, one of the authors of the book, to come as well.
Hey, my biggest issue with this is defining "getting fusion" at achieving Q>5 in steady state. I am fairly confident that SPARC will get Q>5, and I think they'll get there by 2025 as planned (with maybe a year or two of slippage), but this is a long ways off from getting us to economically or climate relevant fusion energy. I'm wondering why you chose this metric for your predictions?
Basically, I think it would make more sense to forecast ARC than SPARC, and I think the odds of ARC working conditional on SPARC are maybe around 30-50%.
Once we get to Q > 5, we've effectively solved the scientific problem of fusion. Ignition (Q = infinity) only requires about twice the triple product as Q = 5 and we would probably want to operate a power plant below ignition (maybe Q = 20) to have more control. At this point, fusion becomes an engineering / economic / regulatory problem instead of a scientific problem.
That's not to say that the other parts of the problem aren't challenges. But I think that they are solvable challenges. I would probably say 80% chance that it there's less than 5 years between SPARC hitting Q = 5 and ARC. ARC here being the first fusion reactor that sells electricity to the grid.
Most of the engineering problems have to be solved to get Q = 5. Between SPARC and ARC, Commonwealth will still be economically functioning like a startup. Startups live on hype rather than profit, and I expect that hype will not be in short supply. Getting from ARC to mass produced fusion reactors that can compete with other energy sources will be harder. I don't know what the regulatory environment will be, but hopefully not terrible in at least one country.
"At this point, fusion becomes an engineering / economic / regulatory problem instead of a scientific problem.
That's not to say that the other parts of the problem aren't challenges. But I think that they are solvable challenges."
I'm less sanguine about them being _affordably_ solvable challenges. The 14 MeV neutron material damage problem looks hard. The tritium breeding problem looks hard. I've heard magnetic confinement fusion designs described as looking more like an LHC particle detection experiment than like a power plant. Thay have expensive, delicate, parts, and it isn't clear how often which parts will need to be replaced.
Getting to Q=5 will be an extremely impressive achievement. I will be the first to congratulate the team that succeeds in reaching it. I agree that the scientific problem will have been solved at that point. Given the amount of deuterium and lithium available to us, we will basically know at that point that we have fuel for a million years.
But we will _not_ know, at that point, whether we have _affordable_ fuel for a million years. It might still be the case, after reaching Q=5, that a better choice might be any of thorium/U233 fission, or solar plus storage, or solar plus (possibly global) transmission.
Then there's the personnel problem. If Igor Kurchatov and Andrei Sakhorov had been operating Reactor Number 4 at Chernobyl the night of 26 April 1986 the world would never have heard of the place. But it was being run by schmos, because you can't afford to have briliant PhDs running a power plant.
A fusion power plant needs to be able to be safely and economically run by trained apes. That's not a trivial challenge.
True! But a fusion power plant doesn't have the ability to have a runaway reaction like Chernobyl did. It _does_ produce neutrons, as you've noted elsewhere, but there is no equivalent to positive-temperature-coefficient-of-reactivity that blew the 1000 ton cap off the top of the Chernobyl reactor. We could have a plasma-instability-wrecks-inner-wall-of-vacuum-chamber, but that is more at the billion-dollar-property-damage level of tragedy, not nearby-city-plus-exclusion-zone-abandoned-plus-fatalities level.
Sure, but we can't dismiss the property damage aspect of this. People are certainly more valuable than dollars, but dollars are still valuable. Let's say you build a $50 billion fusion plant that can supply the entire Eastern Seaboard with electricity, and it starts doing so, and some asshole operating the plant closes Switch B under operating conditions X, which maybe his training didn't quite cover as emphatically as it should, and would have been obviously wrong to someone with a PhD in plasma physics -- and our beautiful fusion plant is wrecked, shazam, nobody killed thank God but will cost $15 billion and 10 years to repair.
For sure potential *investors* would be thinking about that scenario. And it's worth thinking about. Look what happened to Boeing when they figure they could do something inherently less safe in the 737 Max and rely on pilot training to compensate. (And it *did* compensate, at least in First World major airlines with comprehensive training, cream o' the crop pilots, et cetera.)
Conveniently, the 14 MeV neutron problem and the tritium breeding problem are the same thing. But it's still a problem that is potentially too difficult to solve affordably. The best way to figure out how often things need to be replaced is build one and see.
It's possible that fusion won't be the most affordable option for a while. But I do think that we should try to get it there.
I'm fairly worried about the engineering challenges. Tokamaks are just very complicated, there are many parts that can break, many non-trivial challenges we haven't solved, and challenges with operating continuously that we do not have a lot of experience with.
But yes, I agree that once SPARC works, there will be a lot of hype, and that will generate funding, collaborators, more talent, and so forth that will power the more abstract flywheel. This is one of the major reasons for me own optimism.
It's a long and detailed article, so I don't completely understand it. But my takeaways were:
1) Those record Q factors for tokamak/magnetic confinement listed on your graph were *transient*, all-time highs that lasted only for a split second. The record from 1997 has never been matched, and the latest results (after two decades of improvement) are actually lower than that.
2) Their roadmaps and rosy predictions for the future are mostly based on computer simulations. Nothing wrong with that, except that tokamaks have a history of not being able to physically match what their computer simulations.
3) To achieve performance, they (tokamaks) have heavily relied on juicing the plasma with imported Tritium. Tritium is expensive and basically only produced by a handful of aging nuclear reactors, all located in Canada, with concerns over nuclear weapons proliferation. There has been little to no progress on getting a reaction from D-T "burning plasma" which would be necessary for a self-sustaining operation.
4) inertial confinement designs have performed much better in recent years, both in terms of Q and in using Deuterium instead of relying on Tritium. But of course they only last for a split second, not enough to generate any useful energy even if they had Q above 10.
5) That all the fusion "startups" and mini reactor projects have so far mostly failed to produce any fusion reactions at all, let alone anything that would justify their rosy predictions of breakthrough energy in the next decade.
And not in the article but on a personal note, I'm skeptical of any argument like "of course for a mere $500 million a year we couldn't get any results. If those stingy governments had just given us $5 billion like we'd asked, we'd already have met all our goals! C'mon, it's only $5 billion a year, just hand over the check!"
Anyway, not trying to be too negative. I appreciate the review and research overview, and I'm hopeful that you're right. But this other article really put some cold water on my feelings about fusion.
I have not read the article, but I will read it and get back to you.
It is probably a good instinct to be skeptical of people asking the government for $5 billion dollars a year. The burden of proof should be on the people asking for the money. I think that fusion funding is more worthwhile than a lot of the other things that the US government spends this sort of money on.
“ I'm skeptical of any argument like "of course for a mere $500 million a year we couldn't get any results. If those stingy governments had just given us $5 billion like we'd asked, we'd already have met all our goals! ”
What business are you in generally? In mine, it’s generally senior management that says we need X. Ok, fine says the engineering staff. We need 20 people for 2 years and $20 million. Oh no, says senior management, we can’t do that. You need to do it in one year with 10 people and $10 million. Ok, sure, whatever…
A year later and we’re 30% done. OK executive VP Bob, what now? Admit failure? Or say, “mistakes were made” and “we need another year and $10 million?”
When I read the original statement I’m like, “Of course, how else could it work?“. Obviously there is a vast chasm between what can be done and what can be done with the manpower and budget we’ve been allotted.
What if you tell them you're ZERO percent done, and that with a mere $10 million a year you'll never, ever be able to solve the problem? That's what "fusion never" sounds like to me. I mean, they might be right about needing more money, some problems just require a lot of resources at once to make any progress. But it could also be a convenient excuse for failure. Basically every single project is always, always asking for more money, and someone has to tell them no.
I think it's always worthwhile to be a touch skeptical of technology development projections, so I'm with you on that theme.
But I'm a little confused by your point about the budget. It looks like really going after it would have been something like $3 B a year, and instead the US has been spending something like $500 M. So let's say 15-20% of the asked for funding. I don't know about your field of work, but in my experience that level of funding is basically "maintain what you have." It seems like an upside surprise that fusion work has been making any progress, maybe primarily based on external technology improvements like superconductors. In what scenario would you expect anything other than stagnation?
I'm just a cynical asshole who assumes the worst of everyone. So I assume that any big government project is going to be led by self-interested bureaucrats who will ask for as much money as they can possibly get away with, make up some excuse for why they need that funding, and then when it inevitably gets funded at less than they asked (because the other government actors are familiar with this scheme) they point to that less-than-100%-funding as an excuse for any failure.
Given the huge advances in superconductors and supercomputers, you'd think they would have surpassed the 90s Q-levels by now.
I am now wondering if the cooling on funding for fusion research happened due to the cold fusion scandal. I can't but think that gave *all* fusion research a black eye, and all the politicians and other bodies who complained about NASA funding when that money should have been going to [social problems] would naturally vote down any proposals to fund a proven boondoggle. Fusion research was now firmly in the "snakeoil and perpetual motion machines" box.
"Many scientists tried to replicate the experiment with the few details available. Hopes faded with the large number of negative replications, the withdrawal of many reported positive replications, the discovery of flaws and sources of experimental error in the original experiment, and finally the discovery that Fleischmann and Pons had not actually detected nuclear reaction byproducts. By late 1989, most scientists considered cold fusion claims dead, and cold fusion subsequently gained a reputation as pathological science. In 1989 the United States Department of Energy (DOE) concluded that the reported results of excess heat did not present convincing evidence of a useful source of energy and decided against allocating funding specifically for cold fusion. A second DOE review in 2004, which looked at new research, reached similar conclusions and did not result in DOE funding of cold fusion."
"Pathological science, as defined by Langmuir, is a psychological process in which a scientist, originally conforming to the scientific method, unconsciously veers from that method, and begins a pathological process of wishful data interpretation (see the observer-expectancy effect and cognitive bias). Some characteristics of pathological science are:
- The maximum effect that is observed is produced by a causative agent of barely detectable intensity, and the magnitude of the effect is substantially independent of the intensity of the cause.
- The effect is of a magnitude that remains close to the limit of detectability, or many measurements are necessary because of the very low statistical significance of the results.
- There are claims of great accuracy.
- Fantastic theories contrary to experience are suggested.
- Criticisms are met by ad hoc excuses.
- The ratio of supporters to critics rises and then falls gradually to oblivion."
I think "pathological science" also covers the case of Mr. Lemoine and LaMDA.
Ha, I was fresh out of graduate school when Pons and Fleischmann burst on the scene. Haven't heard those names in donkey's years. I don't *think* cold fusion gave a black eye to real fusion, on account of none of the pros took it seriously from Day 1. (Neither of the principals was even a physicist, let alone a fusioneer.) I do recall a few people who ran a few quiet calculations on weird possible scenarios and uniformly concluded ha ha no way.
I think the big mystery was how both these men, sober serious scientists with good careers, fell into this weird rabbit hole of hype and delusionment. It puzzled a lot of people, as if the Queen had been discovered slumming it in a strip club for pin money.
It's possible one effect it had on Congressthings and Senateaux was for them to be more impatient with the "$5 billion/year + 20 years, tops, and we'll have....a really awesome publishable paper for Nature" crowd. They may have thought these unimaginative plodders just need to broaden their horizons, take a page from alternative medicine[1] and astrology, try being less skeptical and investigate weird alternatives that, sure, violate Conservation of Energy or common sense -- but which might actually work out! You never know! There are more things in Heaven and Earth et cetera...
But I think really it was just the same reason the SSC never got built, and the Apollo Applications Program never happened. People got restless after a while with nothing but cheerful reports that concluded no, we didn't achieve any breakthroughs, aren't going to do your constituents a lick of good for their tax money, but by golly we understand the problems so much better now! Another check, please. So they said well here's a pittance to keep going, bceause we're not Neanderthals, we fucking love science too, but come back to us for the big money when you've got something a lot more concrete.
Jassby's claims that magnetic confinement fusion (MCF) has stagnated for the last 25 years, while inertial confinement fusion (ICF) has progressed. I do not disagree: "There has been little progress towards a larger triple product since 2000." I think that this is about to change, while Jassby does not.
There is a simple reason why MCF has not progressed. In 1997, the best MCF experiment in the world was JET. In 2022, the best MCF experiment in the world is JET.
There's only so much we can do with JET's size and magnetic field strength. They could probably get up to Q = 1.5 if they really tried, but not the Q = 5 that you need for a power plant. Instead, JET has been focusing on other important goals like getting the walls right and increasing how long they maintain the plasma. As soon as we get a better experiment, we will get better results, whether it's SPARC or ITER.
It is true that computer simulations did not predict JET very well and underestimated the turbulent transport. Computational plasma physics is a lot better than it was in the 1990s, along with everything else involving computers.
Jassby makes a big distinction between beam-thermal versus thermonuclear fusion. I don't know of anyone else who cares about that distinction. His footnotes for it all point to papers he's authored by himself.
There isn't a physical difference between beam ions and plasma ions. An ion typically has to collide a few hundred times before it undergoes a fusion reaction. So by the time fusion occurs, the ions from the beam are thermalized and are indistinguishable from the ions originally in the plasma.
He also seems to use the terms to describe how the plasma is heated. When the plasma is mostly heated by the beam, then Q must be small, and when the plasma is mostly heated by fusion, then Q must be large, ... because that's the definition of Q. The causality is backward. "For a purely beam-thermal system, the maximum theoretical Q is limited to less than 2" should be "When Q is less than 2, the system must be primarily heated by the beam."
Tritium is very expensive. You don't want your reactor to have to import it.
Each fusion reaction consumes one tritium and produces one neutron. Each breeding reaction consumes one neutron and produces one tritium. It looks like, in order to sustain this, you'd need perfect efficiency, which is impossible.
Which is why we're also planning on including a neutron multiplier: beryllium.
Be + n -> 2 He + 2 n
This increases the number of neutrons, which allows the system to sustain itself with less then perfect efficiency.
Jassby does not think that SPARC is a game changer: "improving cost-effectiveness is surely a distraction for MCF research". I disagree. Cost effectiveness is important on its own. And it means that we can build more reactors faster. It won't take us 25 years to get the money together to build the next big experiment.
I agree that inertial confinement fusion has made a lot of progress recently: "Progress has been extremely rapid. They crossed Q=1 a few months ago."
The big challenge remaining for ICF is going from 1 shot per day to 1 shot per second. NIF is not trying to do this, because fusion isn't their main goal. Maybe Marvel or someone else will figure it out. I hope that they do ! But I suspect that this will be harder than getting fusion using a tokamak.
Thanks for the detailed response! I really appreciate it. I feel like it really ups the level of public discourse on the subject when we good detailed, good faith back-and-forth like this.
If you assume the success of the different projects is independent, your expectation of fusion by 2035 should be >98% and >99.75% by 2040 . So 80% and 90% seems off. Do you think the projects' success is that much correlated?
I don't think that you should be >99.75% confident about anything humanity will do by 2040 because X-risk by 2040 is probably above 0.25%.
Some problems for getting fusion would only affect one player, but others would affect multiple players at once - although probably not everyone. If the venture capital dries up, then that affects all the startups but not the government players. If ITER can't get disruptions under control, then that affects all the tokamaks, but not the stellarators or other designs (although SPARC would probably have figured this out before ITER). We should probably count the 11 partially independent projects in the table as about 3 fully independent projects.
I also threw in a bit of a "maybe this person is crazy" factor, even for myself. The predictions for the particular players are all inside view. The headline predictions attempt to be outside view.
The estimates for particular experiments were gut estimates. But I did take all of that into account for the headline estimates. I thought it was likely that someone would challenge me to a bet on the headline estimates and so made them as defensible as I could.
This review speaks at length about fusion but I'm not clear how exactly it is used to generate power - is it still fundamentally producing heat for steam for electricity generating turbines? Later on the article mentions another option for generating electricity but does not expand. I think the article would have been a bit stronger with a brief overview of the full plant concept including the stages beyond fusion itself.
I'm hopeful that the technology works out, will follow it.
Most of the energy leaves the plasma with the neutron, which deposits that energy in the tritium breeding blanket. Coolant is pumped through the blanket, which takes the heat to a steam turbine.
I think in an older Astral Codex post someone does a break down of the helium produced using fusion. IIRC the amount of helium produced is tiny and would be incredibly difficult to collect.
I've been working on fusion for the last year under an Emergent Ventures grant, and working alongside Schmidt Futures and Adam Marblestone to identify philanthropic opportunities in the space. That doesn't by any means make me an expert, but it's enough that I'm willing to share my opinion.
I think every prediction on this list is about an order of magnitude too optimistic, with the exception of CFS and ITER. I would also clarify that while Q>5 in steady state would be a momentous achievement, it's still puts us a far ways off from fusion energy that is economically or climate relevant. For example, I am fairly optimistic that ITER will "work", but it doesn't actually provide us with a path to commercial fusion energy.
Having said that, I think fusion is absolutely worth pursuing, and that in fact, we're severely underinvesting at the margin even with my revised predictions. Concretely, for the industry as a whole, I would give us a 20% chance of having fusion energy on the grid by 2035, and a 35% chance by 2040.
I'm happy to chat more with anyone here who's working on fusion, or just anyone who's interested:
Thank you for coming and sharing a different perspective !
1. After Commonwealth and ITER, who do you think are the most likely candidates to get Q > 5 before 2040? Do you have more hope for other startups or for government run DEMOs?
2. You think that it is less likely for fusion energy to be on the grid by 2035 or 2040 than I do. Is that because you think that my time frame is too optimistic or because you think that Commonwealth will be unable to solve the problems?
3. I know very little about the philanthropic side to fusion funding. My impression was that most of the money is either government or venture capital. Which of the players have been pursuing philanthropy?
1. I like Zap. There are also a couple pre-launch startups I'm funding and fairly optimistic about. I've talked to people smarter than me who like ICF.
2. I would describe myself as super optimistic about CFS, and would have been happy to invest in their latest round. But all startups naturally carry risk, and I just don't feel like we have that many real shots on goal. For what it's worth, I think the distribution is kind of bimodal, in the sense that if we don't get fusion in the next few decades, we might lose the window of opportunity.
3. Not that many! Simons is one of the major players
Bill Gates is invested in fusion through Breakthrough Energy, and Jeff Bezos is invested, but I'm not sure if either has done much philanthropic giving in the space.
The issue is that energy is fundamentally a market, and fusion is a highly path dependent technology such that subsidizing reactors that aren't going to be economically relevant on their own footing is not a great option.
I am personally excited about philanthropic funding for fusion "tools". Things like material testing/development and tritium systems which benefit a variety of companies and reactor approaches.
1. Zap does look interesting. Z-pinches have had a lot of work done on them, so Zap doesn't have to build everything from scratch. They haven't been a main focus of the fusion community for a while now.
If I remember correctly, a major problem was that it is unstable to kinetic instabilities, even when it is stable to fluid instabilities. Consider a particle running along the central axis of the plasma, with a velocity almost parallel to the magnetic field. This particle will not be confined and will escape out the end. Maybe we don't care: there aren't very many particles like that, so we don't lose much by losing them. But as that part of the distribution function depopulates, there is a two-stream-like instability that puts more particles in that state. So instead of just losing the few particles whose velocities were initially well aligned with the magnetic field, you get a steady leakage that ruins confinement.
I haven't read through their papers yet, so maybe a solution is described there. It's wonderful that they have a bunch of papers publicly available.
The velocity shear is a clever way to allow you to run more current through the plasma without triggering the kink instability. Velocity shear should also help suppress turbulent transport.
(Looking back through this, this really isn't written to a general audience anymore. If anyone wants me to explain anything more fully, please ask.)
2. I could see the case for it to be bimodal. If we don't figure things out in the next few decades, it would mean that the problem is much harder than we expect. I also don't think that there will be nearly as much support if this generation of experiments fails.
3. I was aware of Simons, but hadn't really categorized it as philanthropic funding for fusion. I had not heard of Strong Atomics. Thank you for the resource !
Philanthropy for fusion tools makes a lot of sense. Ideally, you'd try to remove a challenge that almost everyone will face, and make it available to everyone. Materials and tritium breeding are both good options. Diagnostics and remote maintenance would also fit in this category.
I wonder if SPARC will rent out time for other groups to test their materials, etc, with a 14 MeV neutron source.
I consider Helion the most promising fusion startup for a number of reasons, but one of them is that their plan for a commercial reactor has Q = 0.2. This is feasible because of they can recover the input energy with very high efficiency (95% in a prototype.)
You haven't convinced me that this is anything more than the usual techie over-optimism: "yeah all the other times failed, but this time for sure!"
You also don't explain *why* the US etc. gave up on funding fusion research, or why other countries didn't surge ahead with this technology and leave the US eating their dust. Instead, your best candidate is one that is funded by a grab-bag of countries who may or may not decide to pull out at any time.
My impression is that fusion didn't get funded because "too difficult, too technical, a lot of ways it can go ka-blooey, and there were easier, cheaper methods of energy production".
Even what you describe as the new way forward with private funding is a lot of "doing experiments" and not "by 2040 we will have commercial energy generation via fusion".
I'm sorry to say that from this, I'm expecting fusion to be left behind as one of the 'flying cars/moon colonies' dreams of the 70s that never happened, and that renewable energy such as wind, solar and so on will take up the slack (along with nuclear) when it comes to being the shiny new tech for energy generation.
And as Derek Jones points out, you haven't reviewed the book, you've told us (very informatively) about fusion and what your opinion of the state of play is.
To boil the argument down to one sentence: Fusion is closer because building reactors is 10 times cheaper than it was five years ago.
I don't have a good understand of how countries decide how much research money to spend on what projects, but I guess that it involves competitive posturing more than technical plausibility. The fusion community refused to take part in the Cold War, so there never was a Fusion Race.
Investments in renewable energy (particularly wind and solar) over that time period have led to exponential decreases in price. Even if fusion does work on your timeline its not clear why it would be able to compete.
US taxpayers, vice the Federal government, have generally taken a dim view of funding by tax money -- which, please bear in mind, is taken forceably from individuals, it's not a voluntary donation -- any activity that is best characterized as developing new technology from known science, or optimizing technology. We will fund a modest amount of basic research, stuff that won't pay off for decades, if ever, on the grounds that the timeline is just too long for the private sector. And of course research that leads to weapons, since we don't want private efforts in that space at all, and national prestige projects like Apollo, because waving your flag and hooting "We're Number 1! Oorah!" is a thing among primates, and if we pay too little attention to that we alas lose some important elements of social cohesion.
But for all kinds of applied R&D, or anywhere where someone can enthusiastically say "We will have a viable commercial product within the decade!" we generally think "well if this was such a good idea, why doesn't some commercial firm form around doing it? Why should The People bear the R&D costs for value that we can accurately predict will accrue to private shareholders not long from now?"
That's why the Federal government funds basic research into biochemistry, but not actual drug development -- that's left in the hands of Pfizer and Roche and so forth. That's why DARPA funded the basic research around networked computing that gave us a fledgling ARPAnet -- but then got out of the business, and so AWS and Wikipedia and Github are all private ventures.
It's generally been a pretty successful model. At the other extreme, we have the Soviet model, where *everything* was centrally researched, developed, designed and deployed, and that has not worked out well -- not technologically, not ecologically, not economically, and not on humane grounds. It's a cautionary tale.
I think that there is a principled position you could take about what things are and aren't worth government money and conclude that fusion should not be supported. I don't that any government's actual spending aligns with this. Fusion is a more worthwhile than a lot of things the government does.
I do not think that we should be anywhere close to the Soviet extreme. A lot of the recent progress in fusion has been made in the private sector.
Yeah but "the government does a lot of damn silly things with your money already" is not a very persuasive argument for trusting still more of my money to their decision-making processes.
Anyway, I was not making an argument pro or con for Federal fusion research money, I'm just observing that it should not be a surprise that Federal support for the last stage before commercialization -- which is where you're saying we are, remember -- will be meager. Things like Project Apollo or the Manhattan Engineering District are *anomalies* that happen for weird combinations of historical and social reasons, they are not the way things usually work.
The United States tends to spend about ~$20 billion/year on basic science and technology research (much more on medical/bio), so it was always a dubious proposition that fusion power would get like 20% of that, in the absence of some giant special-purpose program (and we're back to Apollo/MED are anomalies).
To your other comment about the US spending $20 B a year on R&D a year, I would argue that number is ridiculously low. The ROI on DARPA, GPS, the NIH, and so on has been huge. For any organization to get on the order of a 100X return on R&D at say 0.3% of the budget ($20 B out of $6.8 T) and to not double down is just asinine. The marginal return for spending more should still be amazing. Sure, there are political constraints on the budget process. We may not be able to always make the right spending decision. But I don't see how anyone can argue that this is the optimal amount of R&D spending for the US.
Perhaps going forward fusion is close enough to commercialization to be handled by the private sector, although I'm skeptical. Retrospectively, unfortunately we've been asleep at the wheel for the last 30 years in terms of public sector support of this research. I would say the same about fission, which I imagine would work about 10X better now if we hadn't mostly stopped developing the technology 40+ years ago.
That's just physical sciences, and I'm roughing it out based on the NSF's budget, and making some vague allowance for DOD, DOE, and NASA grants. NIH spends about 3x more, and overall there's a lot more money in medical and basic biochemical research.
Yes, many people have argued the US spends too little on basic research, but to the extent people want to spend more, these days it's more often on bio stuff. Physical sciences had a heydey from 1945-1985, courtesy of The Bomb, which impressed everyone with what physics could do, but it's been kind of on the wane ever since -- helped along by people like the unlamented former Senator Barbara Mikulski (D-MD) who would inveigh against mere "curiousity-driven" research as frivolous excess compared to whatever trillion dollar corn dole she preferred.
1. Sort of, but only publicly, and only because they are raising grant funding or VC funding. Privately, my sense is that most experts would give a much lower number.
[EDIT: I was mistaken. Yes, I think many experts would agree that SPARC and/or ITER will likely get Q>5 by 2035.]
2.
- It's baseload, so you don't need nearly as much storage (this will be severe limitation for solar as we approach higher penetration).
- It's "clean", meaning no carbon emissions from operation (though you're still using steel and concrete to build the plants.
- It's much safer than fission plants (you can leak some tritium potentially, but there's no risk of a meltdown), meaning no 100 billion dollar cleanup efforts and in theory fewer barriers to public acceptance.
- It's effectively renewable if you're doing D-T since D comes from sea water and plants will be tritium self-sufficient.
Basically, if it works, this is the holy grail for energy. The cost won't be considerably lower than existing energy sources in the near-future, but if things work out, it will at least be competitive even without subsidies.
From your other comments, it sounds like you think that my estimates: SPARC gets Q > 5 by 2030 (70%) and ITER gets Q > 5 by 2035 (50%) are reasonable. Did I understand that correctly?
That is not too different from: Anyone gets Q > 5 by 2035 (80%).
The tritium breeding consumes lithium (particularly lithium-6), which while more common than fission fuels is still a fair way from "effectively free/infinite" as I'd stipulate for "renewables".
Helion is the star in terms of 'society changing energy revolution' with an estimate of 1-6 cents per kWh based on reactor survivability. It also seems like ZAP has the engineering possibility to be a radical change. It will be extra interesting to see what their next experiments do. I listened to a General Fusion public relations presentation and Q and A the other day and they gave 5 - 6.5 cents as their current estimate. I assume Helion is the best physics bet but should be considered a worthy longshot
What I'm very curious about is how much confidence there is out there about the simulation prediction of high power tokamaks tolerating doubled or more density, and if that should straightforwardly double pressure and quadruple maximum output? I imagine then the limit on the commercial price would become divertor and inner wall survivability and be sub 10 cents per kWh with more physics confidence
I don't think that the plasma physics for Helion or General Fusion is understood enough for them to make accurate cost estimates.
Increasing the density of the plasma would be great. It is also hard to do. Higher densities tend to drive more instabilities, which make it harder to keep the heat in the plasma, increase the chances of disruptions (for tokamaks), and make compressing the fuel more difficult (for other designs). If the limit is divertor survivability, then the plasma physics problems are solved and you need a materials scientist to help you.
Did something happen to the equations as well? They seem to be missing equals signs, and the numbers that are said to be subscripts and superscripts are appearing on the same baseline.
Is there a reason dense plasma focus is not a creditable approach to achieving commercial fusion? I didn't see that particular method discussed in the review.
Great article! I had no idea we made consistent progress on fusion for so long. However I'm very surprised that the author thinks that three of the current major companies working on fusion are likely to succeed (70% by 2040). That seems incredibly unlikely to me, as just in general most startups fail.
The upper level of Q is infinity. This is 'ignition', when you don't need any external heating for the plasma.
The fuel costs should be very low because the energy density of fusion fuel is extremely high. 1 gram of deuterium and lithium releases as much energy as 1 ton of coal. The construction and maintenance costs will be more significant than the fuel costs.
It doesn't seem to be controversial that we will reach fusion eventually if we follow tokamak extrapolations (though I think your timeline is super optimistic). The question is how cheap and scalable would this generated energy be. It is very possible CFS's SPARC will go online, generate energy, but self-destroy through neutronicity.
In any case, I'd love to hear: what is your prediction for fusion energy costing under 3.2¢/kWh (or any other price) in 2035 or 2040?
I strongly suspect fusion power has already been solved, although the specific details is a confluence of both conspiracy theory and culture war. (Basically, just, suppose a government has fusion power, and imagine what they'd do to situate themselves before releasing it.)
As someone in the fusion community, I can say that we're really bad at conspiracies and culture war. Unless you count tokamak vs stellarator vs inertial confinement as a culture war.
No government is competent enough to have both developed fusion power in secret (in a way that leading plasma physicists in public isntitutions cannot) and managed to keep it a secret for years or decades.
I think it has been weeks or maybe months, not years, if I am correct. (Big if. I don't put a lot of credence in the idea, maybe like 5%, but for the kind of idea it is, this seems insanely high.)
I'm also surprised with the amount of credibility you give to NIF, which seems to be generally accepted as a nuclear weapons maintenance program dressed up as fusion research. My impression was that no one in fusion power takes the NIF seriously as a path to actual energy generation.
They definitely are a nuclear weapons maintenance program, with some fusion research on the side. They have increased their triple product by an order of magnitude in the last two years, which is impressive. They still have the major challenge of increasing their shot frequency from 1/day to 1/second, which doesn't seem to be one of their goals.
Their work might lead to someone else making inertial confinement fusion work (like Marvel Fusion). I don't think that they will do it themselves.
I know they were lying their arses off about their Q-value a few years ago by representing "the heat that got into the very centre of the pellet" as the denominator. Have they stopped lying?
Livermore? If they tell you what they're really doing, or even thinking, they have to kill you afterward. Not sure even Sandia is as professional paranoid.
They are no longer using the definition of Q that they were a few years ago.
I'm reluctant to say that they're lying because most of the terminology was developed for magnetic confinement fusion, so it's not obvious what the best way to translate the terminology is. They did pick the translation that made them look the best.
They now report Q_alpha, which is what fraction of the total heating is done by the alpha particles produced by fusion. Q_alpha = 1 corresponds to 'burning' instead of 'breakeven'. This isn't what tokamak people usually use, but it's unambiguous to translate.
NIF has recently gotten Q_alpha > 1. The main thing limiting the progress towards inertial confinement fusion now is shot frequency, not Q.
I'm sorry, but no. It doesn't matter what they call the number, what matters is that they are still considering *only the energy delivered to the fuel," and they are still saying "A net energy gain would require fusion yields greater than the laser energy, 1.9 MJ..
This is wrong. A net energy gain would require fusion yields greater than the *input energy* to the laser. To generate a laser pulse of 1.9 megajoules, they need to discharge a 422 megajoule capacitor bank. Even if they generate, say, 20 megajoules of actual fusion output, they'd still be looking at an end-to-end efficiency of under 5%: they don't suddenly start producing useful energy by increasing the shot frequency.
If by "get fusion" we take the definition in footnote 1 (somebody does an experiment that gets Q > 5), then yes, we will probably get fusion on something like the timeline the author describes. However:
1. Q = 5 is *far* from commercially viable. Q represents an energy gain in terms of the energy going into the plasma. It does not account for all the other energy needed to run the system. The most optimistic number I have seen is that Q > 20 is commercial fusion. And even that is optimistic because of point #2.
2. Neutronic fusion (basically everyone doing D-T fusion) relies on neutrons crashing into stuff and generating heat, which then boils water, which then drives a steam turbine. So one input into the electricity economics for fusion is the cost of the generating equipment, the steam turbine itself. If we look at the other modes of electricity production that also use steam turbines, and compare the cost of their steam, we will see that fusion is clearly worse than everyone else. Coal: we mine this thing from the ground and set it on fire and it gives us heat to make steam. Fission: we mine these magic rocks from the ground and hold them together and it gives us heat to make steam. Geothermal: we drill holes in the ground until we reach hot temperatures, circulate water, and it yields steam. Fusion: we build the most complex and finnicky machine ever known to man (read: very expensive) and then it produces heat which we can use to make steam. Neutronic fusion is an expensive way to make steam, so the economics are unlikely to work if it is actually competing on a level playing field with other ways of making steam.
3. The insanely complex and finnicky machine neutronic fusion uses to make heat will need to undergo maintenance, and perhaps more often than other machines, because it is constantly being bombarded with radioactive neutrons. When it needs to undergo maintenance, it will be radioactive because of all the radioactive neutrons that have bombarded it. So maintenance will be expensive.
4. The neutrons emitted by neutronic fusion can be used to breed plutonium and other fissile material, so the technology will have to be closely controlled, which is a further headwind on it ever becoming economic.
5. Fusion advocates have tried to get fusion to be perceived as "safe" because it cannot lead to a meltdown. While it can't melt down like a fission reactor, fusion can suffer from a confinement failure (i.e., a big explosion). A confinement failure is likely to strew radioactive parts everywhere in its vicinity.
D-T fusion is indeed the closest technology to scientific breakeven (Q > 1) and maybe even to something like Q > 5 like the author suggests. But that does not mean it will ever be commercially viable. I believe that the scientists working on it know that it won't ever be commercially viable, but they don't want to say so because they want to continue to get funding either from governments or private investors to achieve the breakeven milestone.
" neutrons crashing into stuff and generating heat, which then boils water, which then drives a steam turbine"
I do like how all the cutting-edge future tech in the end comes down to "and then we use it to drive tech invented in the 18th century for pretty much the same purposes in the same way they were using it in the 18th century".
I'd think you'd love to hear about Project PACER, which was a proposal to create fusion energy by detonating thermonuclear bombs in salt caverns and letting the heat boil water to drive steam turbines: https://en.wikipedia.org/wiki/Project_PACER. It was part of the broader 'Atoms for Peace' program of Project Plowshare, more specifically an extension of the Project Gnome nuclear test that sought to harness the power of underground nuclear weapons tests for peace instead of war: https://en.wikipedia.org/wiki/Project_Gnome_(nuclear_test). The Soviet counterpart was Program #7, a.k.a. Nuclear Explosions for the National Economy: https://en.wikipedia.org/wiki/Nuclear_Explosions_for_the_National_Economy.
(See also, Project Orion: https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion). If we ever need to build an interstellar colony ship in short order, or launch a last-ditch asteroid diversion mission a la the movie Armageddon, Project Orion would be our best hope with current technology.)
That's because the power generating event is happening incoherently on the atomic scale. That is, you are essentially generating heat (= accelerating particles) at Step #1, so you can't help but put it to use as a heat engine -- and so off we go to needing a working fluid that cycles conveniently between expansion and contraction at normal ambient temperatures -- hello H2O! -- and we just add on all the usual steam power plant tech after that.
There are ways to generate powr that *don't* generate heat at Step #1, e.g. using falling water or tides, which are all harvesting *coherent* motion, and these can go directly to electricity generation (or some other form of useful work) without having to pass through a heat engine.
But basically there *are* only two ways to get useful "energy" (= work). You either convert some other form of work (tides, sunlight) to the form you want (electrical potential), or you convert heat to work via a heat engine. Unfortunately, *anything* that relies on events at the atomic scale -- combustion, fission, fusion -- is going to be making heat because we have no way of making it "coherent" (= happens at specific times, and in specific directions we specifiy).
Mind you, living cells aren't subject to the same restrictions, because they can and do engineer at the atomic level. That's why we can "burn" glucose without literally burning it, using steam expansion and so forth. Enzymes can convert the potential energy in glucose + O2 into the (much more convenient) potential energy of ATP directly, without having to go through this hokey pokey of a working fluid expanding in a cylinder et cetera.
If we were able to do the same, engineer at the atomic level, then we probably wouldn't dick around with fusion power. The Earth is continually bathed in 10^17 W of high-quality work (sunlight), which is more than we could conceivably use for a long period, even given the most optimistic assumptions about growth. If we could engineer at the atomic level, build equivalents to chloroplasts that produce whatever useful substance or energy storage material we like, that would clearly be the way to go.
" If we could engineer at the atomic level, build equivalents to chloroplasts that produce whatever useful substance or energy storage material we like, that would clearly be the way to go."
"PV conversion efficiency is the percentage of incident solar energy that is converted to electricity. Though most commercial panels have efficiencies from 15% to 20%, researchers have developed PV cells with efficiencies approaching 50%."
I think the major limitation at this point is storage. ( There are quite a few energetically reasonable options for storage, from various battery technologies to pumped storage. IIRC, the problem is getting their costs down far enough. )
Well, sure, that's the point. The plant gets glucose out of a chloroplast, a nice compact easily transported and stored fuel, not electricity which it has to use right away or waste. That's also why a comparison of energy efficiencies isn't especially relevant -- the plant is not *trying* to produce high-energy electrons, that's not its figure of merit. What you want to compare is a solar-powered chemical plant that can turn CO2 and water into gasoline. When that gets to the efficiency of a plant, we'll have something to brag about.
Well, we _do_ use electricity for a lot of our energy needs. Economical storage is a problem, though one with many partial solutions (e.g. electric cars are more expensive and shorter range than gasoline cars, but they aren't ludicrously uneconomical - off by maybe 2X, not 10X). If we used hydrogen for storage (yeah, I know, volumetric energy density is crappy - consider it for stationary applications where large volume storage is ok) the round-trip electrolysis->fuel cell efficiency is around 50% - which is better than the conversion efficiency to glucose in a plant, which loses around another factor of 4 going from chlorophyll excitation to glucose.
Those numbers don't really add up by my intuition, although I can't be bothered to check it in detail alas. Your Wikipedia article asserts an efficiency of (full-spectrum) light to glucose dG of ~11%, which sounds about right. Last I looked at solar the standard light to volts efficiency was something like ~18%, and I'm a priori doubtful you can make and store H2/O2 at better than 50% total efficency. And then let us remember that H2/O2 just gives us fuel for a heat engine --- and yeah my god a serious storage and transport issue, definitely a wretched way to store energy -- so if you want to do useful work with it, you're going to get whacked by another factor of 1/3 when you run your heat engine -- the cell has no such problem with using ATP 'cause it's not using a heat engine.
Anyway, while it's a mildly interesting hypothetical, it isn't germane to my point, which is that if we could engineer light harvesting and the construction of arbitrary molecules the way life has, it would beat the hell out of *any* conceivable energy generation coupled with manufacturing technology we've got. I'm sure you've read Stephensons "The Diamond Age." Like that.
> *anything* that relies on events at the atomic scale -- combustion, fission, fusion -- is going to be making heat because we have no way of making it "coherent" (= happens at specific times, and in specific directions we specifiy).
Isn't Helion's design a counterexample to this claim?
It's a fusion power design that isn't a heat engine. They do their fusion in discrete localized shots, and the plasma expanding in the magnetic field generates the electric current.
Ah I see. Pretty fancy. I think that's still a heat engine, because the basic driving force is expansion of the plasma as it gets heated by fusion. The expanding plasma isn't pressing on a turbine fan blade and thereby turning a generator, it's more or less doing the generator thing directly, but that isn't really relevant to the thermodynamics.
I strongly agree with points 3 and 4. Permitting, construction times and operations and maintenance costs have a huge impact on the cost of power. Compare that to a solar farm and battery setup which can be rolled out in months and doesn’t need much maintenance for twenty years.
I have not looked at the details of how to make a fusion power plant commercially viable. I'm guessing that a lot of the answers are currently unknowable. This seems to be your main point, and I doubt that I will be able to respond to it satisfactorily. SPARC is about 1/10th the cost of ITER, so progress here is definitely being made.
Here are responses to your other points.
1. In terms of the triple product, Q = infinity is only about twice as hard as Q = 5. Getting Q > 5 is most of the technical challenge.
2. There isn't a level playing field. If there were, my guess is that fission would win. But it's currently mired in a regulatory mess. I would love to see that change, but wouldn't bet on it. Coal is cheap until you count all the people it kills. Most of what I know about geothermal comes from your blog post. Maybe it is a better option, but I would like to see both available.
3. The tritium breeding blanket should block most of the neutrons from getting to most of the components. But yes, the maintenance will be radioactive.
4. This is possible, but I don't think it's a big challenge, for several reasons. (a) Over half of the world's energy is used by countries that already have nuclear weapons. I'm not as worried about e.g. China using commercial fusion reactors to make weapons if they can just get one from their stockpile. (b) Fusion reactors are much easier to inspect than fission reactors. For fission reactors, you need to keep track of how much fuel is where continually. Fusion reactors should have any uranium or plutonium there at all. Detecting if an element is present is much easier than keeping track of how much there is. (c) I don't think that anti-proliferation inspections are a significant fraction of the cost of fission plants today. The easier inspections for fusion shouldn't a significant fraction of the cost of them either.
5. No it's not. Fission reactors meltdown because they contain months worth of fuel that can all burn at once. Fusion reactors would contain minutes or hours worth of fuel. There is not enough total energy in the reactor at any time to breach the building. The worst disruptions would melt part of the interior of the reactor, which would be expensive to fix. But it would not strew radioactive parts everywhere in its vicinity.
I know lots of people who are working on fusion who believe that it will become commercially viable. It's possible that we're wrong, but that is not the consensus of the community.
"I have not looked at the details of how to make a fusion power plant commercially viable."
Having looked up the book you reviewed online, by the table of contents they cover that in chapter eight, or at least they cover designing a tokamak power plant. Not having read the book, I don't know if they cover how to make it commercially viable.
I think that is an important omission; I can understand you being excited by interesting new science, but if you're trying to sell it to us as more than 'fascinating research' by means of 'infinite cheap clean energy' , then you really have to show how we get there. You haven't addressed *why* countries didn't put funding into fusion research, and 'I dunno, maybe Cold War?' is not a good enough reason. This is that "$100 bills lying on the sidewalk" problem all over again.
The book does have a description of what you would have to have in a power plant and what you would want to optimize. But it does not give cost estimates for construction or maintenance for an optimized reaction. I don't think that good estimates are possible right now.
For example, we need to know how long various materials can survive when bombarded with 14 MeV neutrons. In order to test that, we need to have a good source of 14 MeV neutrons. Which means we need a fusion reactor. Experimental reactors are necessary in order to make precise cost estimates.
I have not claimed that fusion is 'infinite cheap clean energy'. I do claim that it is clean and that there is a lot of fuel, but I don't know how expensive an optimized plant will be. Having an entirely new source of energy is exciting, even if it isn't better than everything else in all ways immediately. For example, I could see an economy with intermittent wind & solar power, nuclear baseload power, and fusion peaking power, even if fusion does not end up being the cheapest.
This is not a $100 bills lying on the sidewalk problem. In the analogy, the up front costs are trivial. This is not true for fusion.
Why do countries decide to spend research money the way they do? These decisions are made by politicians for political reasons. Physics megaprojects might get funded because for the military (e.g. Manhattan), for competitive status (e.g. Apollo), to give the public lots of inspiring pictures (e.g. Hubble), or because famous scientists support them (e.g. particle accelerators). Controlled fusion is not immediately relevant for the military. By not taking part in the Cold War, fusion removed the possibility for competitive status seeking - and further reduced military support. I think our pictures are cool, but we're not going to able to compete with space on that. There haven't been many famous plasma physicists, compared to high energy physicists or astronomers, and I'm not sure why. Whether or not fusion is useful politically now is more relevant to government funding than whether it's useful economically in the future.
"I have not claimed that fusion is 'infinite cheap clean energy'."
Some of your partisasns are doing that for you, or extrapolating a lot further from what you have said:
"(a) A lot of people will be upset if engineers solve this problem and the world continues on in energy abundance. How can we have Mad Max or some other dystopian future if engineers solve all the problems? Mankind must suffer!
(b) With infinite energy we don’t have to live here.
(c) Scale - solar will never make getting you to orbit cheap. Fusion can. You can’t think in terms of your energy needs now, with current technology, you need to think of “your” energy needs 50 or 500 years from now."
"In the analogy, the up front costs are trivial. This is not true for fusion."
Your book review would have been better if you had included acknowledgements of this type in the body of it, rather than in replies to comments. Yes, you want to sell us on the fantastic amazing science and the possible future benefits - but you also need to anticipate and meet the possible criticisms, and acknowledge that it's not going to be as easy as "Throw money at it and we'll have the Jetsons future in fifteen to thirty years time".
"Whether or not fusion is useful politically now is more relevant to government funding than whether it's useful economically in the future."
And *that* is part of what I have been trying to get at, as to why the Fusion Future may not come around in the timescale, or with the rosy results, that your essay hopes for.
Thank you for answering this. I think that you do have a point about fusion not being military benefit or politically favoured, but I also think there has to be something more going on - why wouldn't any country want the kudos of "we were first to solve this huge problem and now have safe, clean, cheap energy"?
"Some of your partisans are doing that for you, or extrapolating a lot further from what you have said:"
That is a lot more than what I said. I stopped following that thread when it turned into a technology good vs technology bad vs technology nonexistent argument.
"Your book review would have been better if you had included acknowledgements of this type in the body of it"
I thought I had in Figure 1 and with sentences like "the fusion community has been gathering money from all around the world for decades for a single project". Maybe I was not clear enough.
"as to why the Fusion Future may not come around in the timescale"
A big part of my argument is that we no longer are dependent on government funding. Commonwealth has made fusion cheap enough that it's within the range of private venture capital. It still hasn't been done yet and it still isn't cheap enough to compete with other energy sources, but it's a lot closer than it was even 5 years ago.
"why wouldn't any country want the kudos"
Because countries don't think. Politicians think. The question is: Why wouldn't any president want one of their successors to solve this huge problem?
You say that neutronic fusion has no economic future because it's just another thermal energy competing against many other thermal energy.
I would add that thermal energy cannot grow much more because of thermal pollution.
What are the prospects of aneutronic fusion (with direct energy conversion to electricity)?
This is for me the real question: If we get aneutronic fusion, it will open a future of "unlimited" energy. Ok, let's define "unlimited" as 1000x more energy than now. Note : 1000x has already happened since the beginning of industrial revolution.
There are two relevant aneutronic fusion reactions: D-He3 and p-B.
The Deuterium - Helium-3 reaction requires about 10 times larger triple product, while the proton - Boron reaction requires about 100 times larger triple product than DT fusion. I think that both of these are achievable eventually, but they will not be the first generation of fusion reactors. You also need a source of helium-3, which might require mining the surface of the moon.
The plans of helion is to do 2/3 of D-D and 1/3 of D-He3.
The D-D reaction yields with equal probability T+p and He3+n. So D+D reactions produce as much He3 as the D-He3 reactions consume.
Helion does not consume He3, so no need to mine the moon.
Actually, Helion reactor produces tritium and hence He3 if you wait a bit. Because tritium has a half live of 12.5 years and decays into He3.
Why do you say in your article that the helion reactor is 25% D-T ? Where did you get this piece of information? It seems to me an error that could be easily corrected...
They start with a plasma with pure deuterium. As it starts to fuse, it produces an equal amount of helium-3 and tritium. Both the helium-3 and tritium will then fuse with deuterium.
In order to get 2/3 D-D and 1/3 D-He3 with no tritium fusion, Helion needs to have a way to reliably extract tritium while the fusion reaction is going on. I don't know of a way for them to do that.
Either way, I think that it's best to describe this as predominantly D-D fusion, rather than as D-He3.
As I understand they start with a mix of D and He3, which leads to the desired D-D and D-He3 reactions, but since it's pulsed, secondary reactions of the D-D fusion do not happen much because the produced He3 and T are way too high energy to fuse and have no time to cool down to the right range.
What I do not know is how they plan to capture these He3 and T. Seems less harder than the fusion per se though.
<Disclaimer that I am not an expert on Helion's plans and might be wrong.>
I'm trying to back-of-the-envelope this.
There have to be twice as many D-D reactions in any shot than D-He3 reactions in order to sustain it.
Do you know what temperature they're operating at? I'm guessing about 500 keV. At which point, the cross sections for the three reactions are about equal.
Do you know what fraction of the particles fuse on each shot? To get very few D-T reactions, I think that the answer needs to be small, but that goes against the goal of getting a lot of power out.
I'm also not sure why they're trying to not have D-T reactions.
D-T is the easiest reaction to do and releases about as much energy per reaction as D-He3, and much more than D-D.
They don't have an aneutronic reaction. They'll have to shield the neutrons from the D-D reactions (and any from D-T reactions that do occur). Maybe they think that they can shield lower energy neutrons but not higher energy.
In order to separate out the T afterwards, they probably need to use both centrifugal (D vs T) and chemical (T vs He3) separation. Definitely easier than the fusion, but it's an extra efficiency cost.
The Helion reactor is pulsed. The pulses are short enough that the fusion products don't thermalize before the pulse ends (they can do this because they recover the input energy with very high efficiency). This means the T produced is energetic, putting the DT cross section well below the peak (which is at lower energy). I believe that only a very small fraction of the produced T ends up fusing. The problem becomes separating the T from the exhaust D so it's not reinjected into the reactor.
This scheme also solves the "ash removal" problem, which also faces DD reactors. Steady state DD reactors would need to be able to separate particle confinement and energy confinement; this was a selling point of Dipole Fusion (the old LDX experiment.)
Can you expand on #2? I've heard people say "but steam turbine" and it always feels like they're skipping some steps in their explanation.
The neutrons from D-T are a problem, but they are significantly less than for fission, which we can handle. And viable D-T fusion means He3 fusion is around the corner.
You don't even mention the worst issue Lidsky identified: the horrible volumetric power density of DT fusion reactors. If you look at gross thermal power production per volume (looking at the whole reactor, not just the plasma) you get:
ITER 0.05 MW/m^3
ARC 0.5 MW/m^3
PWR fission reactor 20 MW/m^3 (volume = that of the pressure vessel containing the core)
DT reactors will be at least an order of magnitude larger than fission reactors of the same power output, and present far more challenging problems of engineering. How can one expect the fusion reactor to be cheaper than the fission reactor? If it's not, how will fusion power compete with the energy sources that are already driving fission out of the market?
For this and other reasons, I consider Helion the least dubious of all the fusion efforts.
BTW, any fusion book that doesn't mention Lidsky, and any review of a fusion book that doesn't mention if it mentions Lidsky, get thumbs down from me.
I am not sure tokamak DT fusion will ever do better in cost than existing fissions reactors but let me try to argue why it could happen:
1. the primary fuel, deuterium, is dirty cheap
2. the learning curve will drive fusion prices down. Because of (perceived or real) safety issues the fission reactors are getting more expensive generation after generation. At the contrary, for fusion we can imagine a low regulation environment allowing competing companies to experiment cheaper and cheaper solutions.
Fuel is already a minor part of the cost of power from a fission reactor. So, maybe at some point if uranium gets scarce this could change, but until then the low cost of deuterium (and lithium; don't forget that's the other fuel being consumed to make tritium in the blanket) can't help much.
Most of the cost of fission power is from capital cost of the power plant itself. And there, DT fusion is operating at a grave disadvantage vs. fission, due to size and complexity.
As for safety, the major problem from the point of view of a utility is risk of losing the power plant. Fusion reactors put much more complexity in the hot part where repair is very difficult, if not impossible. Making this part sufficiently reliable is likely to be very expensive. (This is another point Lidsky made.)
Yes, I agree with you. The fast neutrons are a scourge. I actually don't think DT fusion could do much better than fission, probably worse. And fission is already not competing well with alternatives.
What I really think would be transformative is aneutronic fusion with direct energy conversion. No boiling water, no fast neutrons, shipping container size generators.
As in helion energy plans. They've received half billion to reach net electricity by 2024. If they succeed this will completely change the energy landscape.
Fusion does have other significant advantages over fission in radioactive waste, proliferation risk, and meltdown risk.
It is plausible that properly regulated nuclear fission would be cheaper than fusion. I don't think that's obvious just based on the power density because volume is not the only thing determining the cost. But "properly regulated nuclear fission" is not the world we live in. Instead, we have a hostile regulatory agency. Costs to build new fission power plants range by a full order of magnitude between different countries. Fusion is trying to get regulated like particle accelerators that produce medical isotopes, which would provide a much less hostile regulatory environment.
The formatting has been lost in the nuclear equations, making them very hard to read (like 36Li instead of superscript 3, subscript 6, Li). Some symbols have also been lost, like arrows and what I assume was an infinity symbol. Is there any way to fix this in Substack?
To be fair regarding writing style, he's writing for a general audience and so is probably trying to make it fun and engaging, and less like a heavy research paper.
Stylistic point, you talk about how the triple product is the most important thing for fusion, but don't actually explain what it is. You do quite well in some areas in explaining things in a way that doesn't require much background, but in other places slip over it
Perhaps I was unclear. My point is not that it's impossible to find out, I can google it same as anyone. But when you are writing an article for a non expert audience you shouldn't be relying on them doing their own research to understand what you mean. Because they mostly won't. If they do it takes them out of the flow of the article and you don't know what explanation they're going to read and whether it fits with the flow of information you are aiming for
The peanuts comparison is amusing but doesn't seem particularly revealing since the US is far from the only place finding fusion research. Would be interesting to look at global spending on fusion and how that comaores to other projects.
One of the interesting things about fusion seems to be the unusual level of international cooperation
Another fusion physicist here (just a novice, though.)
What I always was afraid of regarding ITER was an Apollo Program-style Phyrric victory. "Hooray! We've achieved the nigh-impossible! Go us! Obviously not cost-effective, though, so let's basically shelve the whole field." Anything that's cost-effective is going to have to be massively simpler and cheaper than ITER - being just a reactor rather than a super-diagnosed experiment would help, of course - and I do think that the key innovations that come to the rescue probably are indeed going to come from outside the field of plasma physics proper.
Take heavier-than-air flight, for example. Why was it first invented when it was, around the turn of the 20th century? It's not because the Wright Brothers were far beyond everybody else (their advances in stability and control notwithstanding); you'll note that there were rival claimants to the title, some of whom did pick up support from major institutions. But they were all within a few years of the Wright Brothers, anyway - why's that? The reason is that the technological landscape had simply advanced far enough at that point, to the point of engines with sufficient power-to-weight ratios becoming available.
Can you imagine trying to make do without? Achieving heavier-than-air flight for humans by pushing the field of aerodynamics to the limit to make a perfectly-optimized jumbo-jet-sized airframe that is, in the end, capable of briefly lifting a baby into the air because all the rest of its power needs to go into lifting its own weight? There's a Phyrric victory for you.
High-performing superconductors may be, I feel, the equivalent of high-performing engines here. Fusion power is (if I'm not terribly mistaken) proportional to the strength of the magnetic field to the fourth power. Just like you could make a brick fly with a good enough engine, you may well achieve the plasma-physically "impossible" just by spamming more magnetic field strength at the problem.
Which is something I'm hoping for, myself: my interest in plasma-based nuclear power is because it's the sort of power source needed for high-thrust, high-specific-impulse (and thus high-squared power!) space propulsion. Tokamaks aren't the most rockety concept out there, I'd have to admit. So I'm looking forward to what we're able to develop - a brighter, positive-sum vision of the future is something I think is worth working for.
The comparison between high-performing superconductors and high-performing engines is interesting. Some scientific and technological advances are done by lots of people at close to the same time, while some are isolated events. I don't know of any general way to tell which something will be.
"Hooray! We've achieved the nigh-impossible! Go us! Obviously not cost-effective, though, so let's basically shelve the whole field."
This is my fear too, which is getting me called all sorts of names down-thread as a naysayer and a science denier and a hater of goodness, truth and beauty.
I don't see anything in this essay addressing that, which is why I'm pouring cold water on the beautiful dreams. I'm not saying it's *never* going to happen, just that I think that the rosy optimism of "we've cut the 30 years down to 20" may be over-stating the case.
I would like to know all the supporting technologies that've enabled the recent fusion boom. I saw superconductors in the article and I've also heard new magnets.
C.f. the old theory from the SSC comment section about how all technological advancement ultimately comes from materials science
The high temperature superconductors are the (electro)magnets. They're the big game changer. ITER has a list of supporting systems if you want to see more relevant technology: https://www.iter.org/mach/supporting
The 2.5 biggest supporting techs are better superconducting magnets and better computer simulations.
The magnets are an enormous deal because scaling up a 90s-style tokamak design to where we'd expect to get Q > 5 requires some combination of a bigger reactor and stronger magnets. The scaling effects are much more favorable to stronger magnets than to a bigger reactor: ITER and SPARC are expected to have similar Q factors, with ITER being about 3.3x the linear dimensions (35x volume) of SPARC, while SPARC's magnets are about twice as strong. The magnets need to be superconducting because otherwise, even very small losses of power to resistance in the magnet conductors would be a prohibitive tax on the energy balance of the reactor: you can make a research reactor with cryogenically-cooled copper electromagnets, but not a viable commercial reactor.
Computer models have advanced in two significant respects since the 90s. One is that they're informed by a quarter century or so worth of experimental data and theoretical analysis. The other is that a modern computer is orders of magnitude more powerful than a computer of equivalent cost was in the 90s. With a good enough simulation model running on good enough hardware, you can do design studies for prototype reactors much faster with a much higher degree of confidence than you could in the 90s, allowing designs to iterate faster and requiring fewer iterations of actually having to build full-scale hardware to validate your theories.
> The subscript is the number of protons that each element has and the superscript is the number of protons + neutrons [4]. Both of these numbers are conserved: if you add up the total superscript on the left, it must equal the total superscript on the right.
This has been severely mangled; it appears that the superscripts are now just normal text and the subscripts have disappeared.
For 12D, the 1 should be a subscript and the 2 should be a superscript. Same for all of the other terms. There should also be an arrow between _1^3 T and _2^4 He.
The last time I thought about a chemical equation was somewhere in the early 1980s, and even I could tell where the arrow was supposed to be and get the general drift.
Thanks for this whether or not people are willing to classify it as a book review.
15 years at best to get positive outcomes on a few plants. If the best we can hope for is 5 plants with Q>5 in 2040, and they take 15 years to build, then maybe we'll have 20 by 2055. And then maybe we'll have 100 by 2065. How many plants would you need to meet current energy demands?
And then you have the other cost considerations. Sure, the fuel may be cheap, but seriously the engineering hours and other material inputs into these reactors needs a LOT of gains in efficiency before they're feasible. Even if you assume they depreciate as fast as other plants, because of all the specialised equipment their repairs and maintenance is likely to be more expensive and the capital costs will be huge too. There is more to operating costs than fuel, and this is nothing I ever see addressed in any of the pieces I read on the topic.
It's cool science, and we should pursue it. But at this point I think it's the future of energy for the 22nd century, not this one sadly.
SPARC is being built in about 5 years, which speeds up the timing considerably.
I don't have a good estimate for what the operating costs will be. I don't think that anyone else does either (although some people undoubtedly have thought about it more than me), because we have not yet built one yet.
For ARC they project that the magnet performance will start to degrade after 10 years from the neutron flux, and last for some time after that as they are capable of double the operating strength. This seems like a feasible survivability limit
Some of the probabilities seem optimistic. South Korea's DEMO having the same probability of success as ITER when it's basically conditional on ITER's success? All these speculative private companies having a 70% chance of achieving fusion, the same as ITER's, despite having no revenue?
As a total layman it seems like these might be more accurately modelling a question like "How likely is it that XYZ will achieve fusion by a certain date on the merits of their technology, given that they don't go bankrupt or catastrophically fail or get defunded by a new government or anything else unrelated to technical problems?"
If K-DEMO and ITER were perfectly correlated, then they would have to have the same probability: in every world where one succeeds, the other does as well. I do think that it is possible, but unlikely (maybe 20%) for K-DEMO to succeed if ITER fails, or for K-DEMO to fail if ITER succeeds.
It's possible that I am overestimating the chances for some of the private companies. I don't think so (but that is the inside view). If you do replace those probabilities with 50% or even 30%, it doesn't change the headline probability too much (I tried to make the headline probability from the outside view). A few of the most likely candidates, SPARC and ITER, account for most of the probability, and there are other plausible routes in case they fail.
"The fusion reaction chain in the sun burns six protons (hydrogen nuclei) into helium-4, two protons, and two positrons over the course of five fusion reactions. What we do is simpler."
Is this why human-made fusion reactors have so much higher energy density than the Sun? I used to think that fusion of course would be possible, because it's happening constantly in the Sun. But with more research, I found that a glob of sunstuff is slightly warm and slightly glowy, and the only reason the sun is so hot and so bright is because it's so big that the surface area to volume ratio means that that slight amount of heat and light builds up to an incredible degree. The exceptional thing about the Sun as a power plant is that it will keep on burning for billions of years.
Since any fusion power plants we build will be a lot smaller than the sun, and reasonable-sized globs of sunstuff would be pretty useless for power generation, it seems like we'd have to do something fundamentally different from what the Sun does to get useful results.
As I recall, yes, the power density (per volume) of the Sun is comparable to the power density of compost. Thus the different fuels, different conditions, and so forth.
Both statements are true. Another way to look at it is that the solar fusion has to (as a net result) turn 4 protons into 2 protons, 2 neutrons, 2 positrons, and two electron neutrinos. Anything process that needs to turn protons into neutrons + positrons + electron neutrinos is an inverse beta decay, uses the weak interaction - and therefore has a small cross section - and, in human terms, goes slowly.
All of the terrestrial fusion reactions starts with the necessary neutrons already present, either in deuterium or tritium (or, for the breeding step, in lithium).
"The first step in all the branches is the fusion of two protons into a deuteron. As the protons fuse, one of them undergoes beta plus decay, converting into a neutron by emitting a positron and an electron neutrino
...
This is the rate-limiting reaction and is extremely slow due to it being initiated by the weak nuclear force. "
>Anything process that needs to turn protons into neutrons + positrons + electron neutrinos is an inverse beta decay, uses the weak interaction - and therefore has a small cross section - and, in human terms, goes slowly.
Weak force can be fast if it's a decay (uniparticular). The reason PP chain's slow is because it's biparticular *and* weak (the diproton isn't bound, after all).
CNO cycle's not all that slow (the positron decay steps are half-lives of minutes); the Sun's just not hot enough to do much of it.
That's fair. The half life of a free neutron itself is, after all, is about 10 minutes, and it uses the weak interaction to decay. Is the CNO cycle potentially in reach for us? Not that we are going to run out of deuterium in the foreseeable future...
The sun is constrained by the fact that being glowy is a slow way to emit energy. It can only make energy as fast as it loses it as sunlight, because otherwise the core would heat up and become less dense until they were in equilibrium again.
I put the description in the causal order instead of in the ratio order. Energy in goes first, then energy out. I think everyone understood what was meant.
But yes, what you said is the most common way of describing fractions.
I really like the section on private funding. I always figured fusion was impossible because capital markets manage to throw trillions of dollars towards any idea at least as good as “sell pet products online using a sock puppet” or “lend mortgages to people who can’t afford them.” “Unlimited free energy if you overcome some tough physics and engineering problems” seems like at least as good an idea to throw money at. This article seriously updated my priors.
Very much agreed! I haven't been watching private fusion closely, and my priors were at "Historically, private fusion companies were almost entirely jokes or frauds. They make outlandish claims, use completely different designs so they can't build on the progress of Figure 3, and they can be safely ignored. " I greatly thank the reviewer for explaining why this is no longer true, and how this has changed.
Yes, it also helps that the reviewer is himself a plasma physicist and is not a member of the new private fusion companies.
It's not going to be free, whatever about unlimited. The costs of running a power plant have to be covered, and if it's private investment gets there first, you need to return profits to your shareholders. So the costs of generating the power may be much lower than any sources we currently have, but generation costs alone aren't the whole story. Salaries for the workers, maintenance of the plant, all the other accounting and tax costs, government taxes/VAT if applicable are all the extras to be slapped on before Joe Citizen gets his utility bill for domestic power usage.
Proton number is not generally conserved in fusion. For example, in the sun proton-proton fusion gives a product of one deuterium atom, which has one proton and one neutron, via beta decay. It does so happen that D-T fusion conserves proton number. Also, the graph has the wrong inflation correction. The original data is in Fiscal Year 1978 dollars, which converts into 2012 dollars at less than 4:1, so the never-fusion constant $200M in the original becomes $800M in 2012 dollars, not the $1B portrayed in the graph.
The conserved quantities are mass and charge. As long as the weak force is not involved, proton and neutron number are conserved. We typically avoid reactions involving the weak force because they are much slower.
I do not know what the inflation conversion was used for the graph.
I'm trying to find what caused me to write that about Alcator C-Mod. I think that the experimental group was going to be disbanded, but then those cuts were reversed. They still have a presence at conferences: there is plenty of data left to analyze. I don't think that the experiment has been decommissioned, even though they haven't done any new experiments since 2016. I probably should change the footnote once I figure out what actually happened there, or just remove that sentence.
Are there any efforts planned toward building stellarators that use high temperature superconducting coils? From your description, it sounds stellarators are pretty great, so it would be interesting to know if they could also take advantage of a stronger magnetic field.
I'm kind of surprised high Tc superconductors have made such a difference, if you are talking about the perovskite ceramics. Not my field, but I thought they had problems with current density, and surely you need a very high current density for compact tokamaks.
Superconductors not only have peak temperatures, but also peak current densities and magnetic fields that they can support. Broadly speaking, high-temperature superconductors actually have this whole surface defining their peak capabilities moved outward in that 3D space in general, so they can support higher currents or fields at a fixed temperature.
If you say so. Like I said, it's not my field so I'm not au courant in high-Tc research. But as I said this came as a surprise, it's usually hard to send a high current density through a ceramic.
Yeah I haven't been following the high Tc technologies either. But it looks like these are working at ~20 K, which counts as high Tc for super conductors.
20K isn't high Tc, or even new, that was achievable in the 60s. Maybe people have made breakthroughs in ordinary metallic superconductors in terms of fabrication or current density?
Edit: I took a look at their glossy web sites, and it seems ITER is using conventional metal superconductors and cooling to 4K (expensive!) while the Commonwealth people are using YBCO or something similar only made into a tape and cooled to 20K. Apparently it was manufacturing more than anything that held back making magnet wire out of the ceramics, so well done nameless engineers whoever you are.
Yeah high Tc now means a ceramic super conductor. (or something like that I'm not sure... In a few past lives ago, (>20 yrs) I did some 'high' magnetic field stuff. but it was all liquid helium,
with maybe a 'lambda' plate to pump (and cool) the magnet more .. 8 or 9 Tesla was about the in lab maximum. (high field national magnet labs did.. higher fields.) Oh I should add that a 20K super conductor is like ~5 times better than a 4K one. At the minimum all heat engines have to follow the Carnot efficiency (2nd law of thermodynamics).
The superconductors are kept at lower temperatures so they can have higher currents and magnetic fields. The material could work at 77K, but it wouldn't be as strong of an electromagnet.
They make a difference, but not enough of one. ITER has 400x worse volumetric power density than a PWR; ARC is just 40x worse. And the high field of ARC means something like 60% of the mass of the reactor is the steel supports resisting JxB forces.
What would be better would be plasma configurations with much higher beta. FRCs, in particular, have beta around 1, vs. ~0.02 for tokamaks. The FRC companies are using normal conductor magnets, not superconductors (low or high Tc).
This isn't my area of expertise, but depending on what you mean by weapons-grade lasing, it is either already available for purchase for a few hundred dollars, or it doesn't go through the atmosphere.
This is a really interesting and informative article about the state of fusion energy experiments, but I'm puzzled about why it's being presented as a book review. It mentions a book, but seemingly only in passing.
Centralized power generation has large economic incentives to eliminate the competition of decentralized power generation. Centralized power is a target that needs to be defended.
Great article, thanks for spending the time reading the book and writing this review.
You mentioned that stellarators are your 'favourite.' I think that a huge advance in the field in the past couple of years has been on stellarator optimization. Here's some preliminary reading:
Professional skeptics like to say that nuclear fusion energy and AI are always 20 years in the future, but in the last few years there has been measurable and promising progress toward both.
Waiting for fusion energy, whose operational deployment will likely take, yes, 20 years (!!!), conventional nuclear energy is the only viable way to move away from fossil fuels in the short term.
So let's invest more in fusion research, but also in building more old-fashioned nuclear reactors, because that's what we have right now.
The Star Builders is also very good, but not as meaty as The Future of Fusion Energy. It has more interviews with people involved and fewer descriptions of how things work.
I agree that we should be building more nuclear reactors now. But there are a lot of people who disagree. I hope that most of the people who dislike nuclear will like fusion.
No, they won't. Unfortunately these days these things come in partisan ideological packages that good partisan sheeple are supposed to swallow whole without thinking. Since nuclear fusion is "nuclear" something, they will oppose it because they must oppose everything nuclear if they don't want to be canceled and mobbed by their friends. So let's not waste time appeasing them, and start building those nuclear reactors. First fission reactors, then hopefully fusion reactors.
Great article, shame the second sentence is so inaccurate. Most elements heavier than helium are indeed created by fusion - but not all. For example the elements lithium to boron are created by cosmic spallation. Very heavy elements (such as gold) are mostly created in neutron star mergers, which are not really fusion.
Regarding Helion, what's your source for the 25% D-T reaction?
As I understand they plan for 66% D-D + 33% D-He3. Since half of D-D reactions yields one He3, the fuel cycle only needs deuterium as input and has tritium as a (valuable) waste product.
Also D-D reaction is not aneutronic but the neutrons are slower than D-T's
There's another discussion in the comments about this.
My source was that I don't see a way from them to prevent tritium from fusing once its produced. Their claim is that (1) the tritium is very hot when its initially produced, which is true, and (2) the time for each pulse is short enough compared to the tritium's collision time that very little of it would fuse before the shot is over. I don't know if this is true, and would like to see the calculation. But they might not have published the calculation. If you know of somewhere I can read it, let me know.
I'm also not convinced that it's a good choice for them to not use DT. It's the easiest reaction there is. Separating the tritium probably requires two processes (chemical & centrifuge). They already have to deal with some neutrons, although not as high energy ones.
If I were writing this again, I'd just say that there are more D-D reactions than D-He3 reactions, rather than saying it's 25% D-T, in order to reflect my uncertainty.
Helion's schtick is extremely high efficiency recovery of plasma energy. That is: 95% (or more) of the energy that goes into making the plasma, or that is subsequently added to the plasma by fusion reactions, can be recovered as electrical energy to a capacitor bank.
This means that they plan to operate at Q much less than 1, and still achieve positive net energy production. It also means that the vast majority of D ions do not fuse before the plasma is reexpanded. And so, there just isn't time for those T ions produced by fusion to either thermalize or fuse to any great extent.
Not using DT is really the best thing about Helion. DT has engineering consequences that render making a practical power plant very very difficult. Helion's direct conversion approach has huge practical advantages in avoiding the entire thermal side of the power plant (boiling water to make steam to drive turbines.)
Helion is not able to make a power plant with Q < 1. In order to make that work, you would need the rest of the power plant to be over 100% efficient.
If everything works the way they hope, they might be able to make a power plant with Q only slightly more than 1 (maybe Q=1.5), instead of the Q>5 required for a tokamak.
Normally, Q is the ratio of "fusion energy produced / energy injected into the plasma". By that definition, if they can achieve 95% recovery on the injected energy, they could achieve net energy production. That's because for every 1 unit of energy injected into the plasma, they only actually irreversibly spend 0.05 units. The other .95 units can be recycled and injected again.
Current state of the art is q=1 with exorbitantly expensive DT fuel. Economic breakeven would require q>4 using DD fuel instead, and DD requires ~5x higher temperatures. Radiative losses are usually proportional to the fourth power of temperature, and there are other additional ways for electrons to lose energy at extreme temperatures. A design that yields Q=1 at temp T would probably be like Q=0.001 at temp 5T. So they need to get three and a half orders of magnitude better.
By calling DT fuel exorbitantly expensive, I'm guessing that means that you don't think that the tritium breeding blanket will work. Tritium is very expensive, but lithium is not.
Breeding it from lithium would work, but there aren't enough spare neutrons in all the fission reactors in the world to breed enough tritium for any significant fraction of grid power to come from DT fusion.
Back of the envelope calculation:
Each fission of U-235 releases about 200MeV and 2.5 neutrons. Suppose every fission reactor in the world is perfectly efficient so that 1.5 of those neutrons are available for breeding lithium. Suppose further that every fission reactor has an isotopically pure Lithium-6 blanket that magically operates at 100% efficiency and converts every neutron into a tritium. D-T fusion releases 17.6 MeV. So for each 17.6MeV of heat from fusion you had to generate 133.3 MeV of heat from fission. This implies the fission industry must always be at least 7.5x the size of the fusion industry if the latter relies on fission neutrons to breed tritium from lithium.
I don't know what the efficiency of the lithium blanket would be. If that number were sufficiently high then the the recycling of fusion neutrons could support a very large D-T fusion industry.
You breed it using the neutrons from the fusion reaction itself. Each fusion reaction consumes one tritium and produces one neutron. Each breeding reaction consumes one neutron and produces one tritium.
Some of the neutrons will get lost or absorbed by something other than the lithium. To compensate for that, include a neutron multiplier like beryllium:
Be + n -> 2 He + 2 n
This does cost some energy, so you don't want to rely on it heavily. Most of the neutrons produced by fusion will be used to breed more tritium, with the multiplier to make up for unavoidable losses.
"The reaction ...cross-sections of (7Li,n) are much lower...Therefore, lithium heavily enriched (> 80%) with 6Li is a constituent of all candidate materials considered for the absorber."
Very interesting comments to this review. I think the review is good and faithfully follows the book and there is no reason to denigrate it. It's just that the book itself is simply a description of what is the state of fusing at this moment.
Some people apparently expect more from a book. It had to be a story, not just the list of facts. Other people filled to void by inventing the story (that's what our brains do with everything) but that story is boring – “scientists were slow working on fusion energy because it is complicated, but gradually got better and after 30 years or so it will work and everybody will live happy forever”. And now they are criticizing the story and are not happy with it.
Hm, that's pretty much the opposite of how I read the other comments. A lot of people criticize that the review is barely mentioning the book. A large part of it is on developments that occurred after the book was published.
Have you read the book? Is it your first-hand impression that the review faithfully follows the book?
I haven't read the book. But even if it has added something, the book still is most likely the dry description of facts. Now I am not so sure but my point is that people expect the books to be more than that, especially they want a juicy story. Doesn't need to be even relevant to the subject but that's people how think. Even learning dry facts is easier when you put them in a story.
I won't argue against having a nice story. Some books do provide that, others are rather dry.
The review definitely packs the content into a juicy and thrilling story. I am less bullish about it after reading the other comments. But still, I found the review entertaining.
As a european taxpayer (that's not true, I don't pay taxes), I will be very upset if an american company reach fusion before us.
Re Inertial confinement: in a seminar at my university, a person working at NIF candidly admitted that they are mostly working at [CLASSIFIED] and they are not going to produce a power plant
Edit: I wouldn't be this confident in private startups now that monetary policy is tightening. I am afraid that money will flee from risky technological startups towards safer options.
Question not just for the author: assuming that this is correct and the likelihood of nuclear fusion being imminent is underestimated: what is currently under/over-valued by the market?
In the fusion market, I think that the stellarator startups (Renaissance & Type One) are particularly undervalued. This is designed where we have a lot of experience: Wendelstein 7-X is a similar scale experiment as JET. And it avoids one of the major remaining uncertainties about tokamaks: disruptions.
If you think that fusion is likely to revolutionize the electricity market in the next 25 years, then electricity intensive industries are likely undervalued. Aluminum smelting comes to mind as one example, but there are plenty more.
This is a bit like reading an article confidently predicting "we will have GAI by 2035" and then seeing in the fine print that they define "have GAI" as "there is a dense language model with 10x parameters than GPT3".
In case it isn't obvious, this entry should have been disqualified for not actually being a book review. It doesn't even pretend to be one! So, as a book review it gets a full zero out of ten from me. As an evangelising puff piece, about three out of ten - the single word sentences are genuinely cringe-worthy. However, the biggest problem with it is that it entirely skirts over the question of whether there is any possibility of fusion being an economical way of generating energy. Not impressed.
For a supposed review of a book titled "The Future of Fusion Energy", I am missing a big part of, well, the future of fusion energy. Let's say that ITER is a whopping success, and they achieve fusion. Yay for science! But - how long until a reactor can be designed and built that actually generates measurable amounts of power - let's say, a few hundred MW? How expensive would it be? How big would it have to be, just in terms of the physics of transporting away the generated heat? How quickly could this ideally be rolled out?
The thing is, if we want a highly sophisticated reactor that generates power, but costs billions to build and creates a whole bunch of radioactive waste in the process, we already have those. They're called nuclear power plants. Why should I get excited about an alternative that may or may not be technically feasible, may or may not be economically feasible, and may or may not be stable and clean?
"How long until a reactor can be designed and built that actually generates measurable amounts of power?"
South Korea's K-DEMO is will be built during ITER's experiments. It should be finished in 2037 and should deliver power to the grid. China's CFETR also plans to be selling power to the grid by "the 2030s", but they don't have as detailed of a plan yet.
SPARC should be finished by 2028. The next generation, ARC, should sell power to the grid. It takes Commonwealth only about 5 years to build their designs. So they could be generating power before 2035.
"Why should I get excited about an alternative that may or may not be technically feasible, may or may not be economically feasible, and may or may not be stable and clean?"
Technically feasible is the part that I'm addressing here. I (and others) predict that it will be soon. We don't know if it will be economically feasible and we won't have good cost estimates without the experimental reactors. It will be stable and clean.
Nuclear power plants have the risk of a meltdown. I think that people worry too much about it - dam failures are at least as dangerous - but it's a problem for nuclear power. Nuclear power plants contain months of fuel at a time, so when it all burns at once, it releases a ton of energy and can't be contained. Fusion power plants would contain minutes or hours of fuel at a time. So even if everything hit the wall at once, it wouldn't be like a nuclear meltdown.
Fusion plants will produce some radioactive waste, but no high level radioactive waste. There are no spent fuel rods that have to be stored for a million years. The waste from fusion will only be radioactive for decades or centuries, which is a lot more manageable.
I concur with the assessment that this doesn't read like a book review.
I also have significant concerns with the one-sentence brush-off that these probabilities are unlikely to be correlated. They're all tackling the same problem, and their approaches are different but--except for inertial confinement versus magnetic confinement--not THAT different. I believe that the correlation between the probabilities is far higher than the reviewer is letting on... or at least the reviewer needs to show their work.
If you assume that all of the probabilities are completely uncorrelated and combine them, you will get a much higher headline probability than what I said. So high that I think X-risk would make it a bad bet. I then made a series of ad hoc adjustments, assuming things were more correlated than I think and there's more unknowns than I think to get the estimate down to 80% by 2035 and 90% by 2040.
I'm referring to the statement, "Because the players are so diverse, the failures are unlikely to all be correlated."
As a dilettante, my reaction is, "Well, everyone seems to have the same problem with fusion, to wit, getting something hot enough that it fuses without disrupting the delicate dynamic that keeps it controlled in the first place. So why shouldn't they be correlated?"
So I'm not saying you're wrong--I'm not nearly expert enough to have more than an intuitive opinion--but you have to do a LOT more to convince me of the veracity of your statement.
At lot of it comes from trying to figure specific ways things could fail, and seeing if it applies to everything on the list. I decided to not game out a bunch of unlikely (?) failure modes in the review itself.
What if there are just too many disruptions in a burning tokamak? Then the stellarators and other designs could still work.
What if the pulsed designs can never make their experiments work at a frequency of 1/second? Then the steady state designs could still work.
What if high temperature superconductors are too sensitive too neutrinos? Then the larger reactors using more traditional superconductors, or inertial confinement fusion which doesn't use superconductors at all, could still work.
What if putting together something built in pieces across the entire world is impossible for ITER to do? Then all the players with more centralized organization could still work.
What if <something happens to the market> and venture capital is no longer available for fusion? Then the government players still could work.
What if US regulators decide to wage lawfare against fusion? Then the players in France could still work.
When there's more possibilities, a lot more things have to wrong in order for everyone to fail. Everything certainly isn't completely independent, but most of the potential problems do not apply to everyone.
Very interesting to read that the JET record was somewhat of a trick shot utilizing deuterium particle beams aimed at a tritium plasma. However the likelihood of ITER's projected Q being based on that configuration seems vanishingly low. The discussion of potential X-ray sources for ICF with efficiencies of "several tens of percent" is a bolt from the blue which makes me suspicious but curious
As Baking mentions Jassby's projection of several years of deuterium plasma for SPARC seems to indicate he hasn't really incorporated the revolution of high temperature superconductors into his picture of tokamak development prospects. India is building 16 heavy water reactors which will presumably be loaded with tritium about the time it is predicted to be all gone - it seems unlikely that processing facilities won't be built if a bulk demand arises. Tritium breeding may be an obstacle but the specific claim that I have seen of up to 10% of each shot lost to the walls with a burn fraction of ~5% making it impossible to replace does not appear to apply to commercial relevant conditions of hot walls that absorb about 1%. Admittedly that appears to require a 1.2 TBR but it's a far cry from suddenly proclaiming that there will be literally no tritium fueling possible
Jassby's claims that magnetic confinement fusion (MCF) has stagnated for the last 25 years, while inertial confinement fusion (ICF) has progressed. I do not disagree: "There has been little progress towards a larger triple product since 2000." I think that this is about to change, while Jassby does not.
There is a simple reason why MCF has not progressed. In 1997, the best MCF experiment in the world was JET. In 2022, the best MCF experiment in the world is JET.
There's only so much we can do with JET's size and magnetic field strength. They could probably get up to Q = 1.5 if they really tried, but not the Q = 5 that you need for a power plant. Instead, JET has been focusing on other important goals like getting the walls right and increasing how long they maintain the plasma. As soon as we get a better experiment, we will get better results, whether it's SPARC or ITER.
It is true that computer simulations did not predict JET very well and underestimated the turbulent transport. Computational plasma physics is a lot better than it was in the 1990s, along with everything else involving computers.
Jassby makes a big distinction between beam-thermal versus thermonuclear fusion. I don't know of anyone else who cares about that distinction. His footnotes for it all point to papers he's authored by himself.
There isn't a physical difference between beam ions and plasma ions. An ion typically has to collide a few hundred times before it undergoes a fusion reaction. So by the time fusion occurs, the ions from the beam are thermalized and are indistinguishable from the ions originally in the plasma.
He also seems to use the terms to describe how the plasma is heated. When the plasma is mostly heated by the beam, then Q must be small, and when the plasma is mostly heated by fusion, then Q must be large, ... because that's the definition of Q. The causality is backward. "For a purely beam-thermal system, the maximum theoretical Q is limited to less than 2" should be "When Q is less than 2, the system must be primarily heated by the beam."
Tritium is very expensive. You don't want your reactor to have to import it.
Each fusion reaction consumes one tritium and produces one neutron. Each breeding reaction consumes one neutron and produces one tritium. It looks like, in order to sustain this, you'd need perfect efficiency, which is impossible.
Which is why we're also planning on including a neutron multiplier: beryllium.
Be + n -> 2 He + 2 n
This increases the number of neutrons, which allows the system to sustain itself with less then perfect efficiency.
Jassby does not think that SPARC is a game changer: "improving cost-effectiveness is surely a distraction for MCF research". I disagree. Cost effectiveness is important on its own. And it means that we can build more reactors faster. It won't take us 25 years to get the money together to build the next big experiment.
I agree that inertial confinement fusion has made a lot of progress recently: "Progress has been extremely rapid. They crossed Q=1 a few months ago."
The big challenge remaining for ICF is going from 1 shot per day to 1 shot per second. NIF is not trying to do this, because fusion isn't their main goal. Maybe Marvel or someone else will figure it out. I hope that they do ! But I suspect that this will be harder than getting fusion using a tokamak.
I'm a bit confused by the discussion of funding. The claim is made that funding for fusion research has been very low in the US, but lots of expensive experiments are described. I guess international funding is higher? I wish the article went into a bit more depth about funding levels.
International funding is higher. ITER's total cost should be about €20B. Europe is responsible for 45%. The other countries involved, including the US, are responsible for 9% each.
The largest fusion experiments currently operating in the US were built in the 1980s or 1990s. Since the US rejoined ITER in 2003, the funding is almost entirely to maintain & use existing experiments or to build ITER. There have been no new expensive plasma experiments in the US in decades.
NIF gets its funding from nuclear stockpile management. It gets about $300M per year. Their main goals are not fusion.
The private companies get their funding from venture capital. Commonwealth has raised the most: about $2B so far, and they don't seem to having too much trouble getting the funds to build SPARC.
Review aside, my question is how optimized fusion stands up against optimized geothermal energy in terms of economics and practicality. MIT seems to be the center of the energy universe, so it's not surprising that the front runners in both fields are start ups coming out of there.
Quaise is one I'm really excited about, and it seems to be imminently practical. But I would love to see an article as in-depth as this discussing the issues and history of the field. Because it seems to me that, were this technology to get working, the simplicity of a deep hole that can be plugged into existing coal fire plants (and then run forever) without building-sized techno-marvels would pull ahead.
Green, safe, equitable, universal, stable, creates jobs for an existing workforce that we otherwise want to eliminate. The list just goes on and on. It's like solar without the batteries or scrapyard panels eating up ecosystems. Like nuclear without the radiation. I'm not paid or anything I'm genuinely just kind of mind-boggled.
So am I missing something or is this actually possible?
I think it's still an open question whether it's possible. It certainly is an interesting idea, worth pursuing, but drilling 20 km down at extreme heat and pressure is a daunting challenge. At some point the earth just forces itself closed faster than you can keep it open. And you do have to go down that far to get the best benefits of geothermal, since high pressure (supercritical) water at high temperature carries far more energy and can be used more efficiently than just regular high temperature water. Drilling "halfway" doesn't get much practical result.
Their drilling tests are going to be starting relatively soon, I think some time next year for the first one. I think they estimate $50 per MWh. Very excited to see what happens
I'm also excited to see what happens! But I get skeptical when I see a precise, simple, linear number like "$50 per MWh" for such a complex operation that is nowhere close to being operational yet. You'd think it would at least have a large fixed cost plus a marginal cost but apparently that sort of math is too hard for a venture capitalist to understand.
I was wrong, they predict $10-30 per MWh based on a certain drilling cost being achieved with a full size test rig to be built in 2024. There's a new video about it on Undecided by Matt Ferrell on youtube
One comment noted a possible risk to success in the transition areas where the glass lining produced by the energy drill will be weaker
Donning my hat as Resident Nay-Sayer, I think geothermal works best where there are volcanic fissures already open. Iceland seems to be one https://nea.is/geothermal/ and Hawaii another, and the Hawaii plant shows the risks:
They want to drill very, very deep. 20km down, where the temperature is reliably high almost no matter where you are. By comparison the deepest well bored to date is about 12km.
"The Iceland Deep Drilling Project (IDDP) is a long term study of high-temperature hydrothermal systems in Iceland. The IDDP is a collaborative effort by a consortium of Icelandic power companies and the Icelandic government, formed to determine if utilizing supercritical geothermal fluids would improve the economics of power productions from geothermal fields.
Over the next several years the IDDP expects to drill and test a series of boreholes that will penetrate supercritical zones believed to be present beneath three currently exploited geothermal fields in Iceland. This will require drilling to a depth of about 5 km in order to reach hydrothermal fluids at temperatures ranging from 450°C to ~600°C.
IDDP well A feasibility study completed in 2003 indicates that relative to the output from conventional geothermal wells, which are 2.5 km deep, a ten-fold increase in power output per well could result if fluid is produced from reservoirs hotter than 450°C .
A typical 2.5 km-deep geothermal well in Iceland yields power equivalent to approximately 5 MWe. Assuming a similar volumetric inflow rate of steam, an IDDP well tapping a supercritical reservoir at temperatures above 450°C and at a pressure of 23-26 MPa may be expected to yield ~50 MWe."
That makes me wonder why the difference? There's a heck of a change from "we're deep drilling at 5km" to "we're deep drilling at 20km". Is it just that Iceland has the volcanic activity nearer the surface?
That's an interesting project, and it makes sense that supercritical water would let you extract a much higher flux of heat, although I wonder if they need to keep it supercritical for some part of its journey up, which would be tricky perhaps.
Yah Iceland is basically sitting on top of some giant freaking lava pool. Definitely not the case on the Eastern seaboard of the US, which is old, cold, continental crust. A little surprised they don't first try it out West, where there is magma quite a lot closer in various places, e.g. in Death Valley there are actual hot springs. Also Yellowstone, of course, but people would probably get cross if they brought some honking big drill rig into the park.
Not really. I'm not at all an expert, so don't trust me here more than anything else.
I think of it more as mining the heat of the crust. It's not renewable - they'll extract heat a lot faster than it diffuses up from below. So the wells will run dry. But "renewable" isn't something you should care about. What matters is if it's environmentally friendly and if there's a lot of it. Both appear to be true.
I don't know if it's technologically possible. Or rather, what depth is technologically possible and whether there's enough heat at that depth. But it would be very exciting if it works.
Question for the reviewer: I read a short story a long time ago (so I might be misremembering and they were trying to get fission instead of fusion) and in the story they thought that deuterium-3, an isotope of hydrogen with 2 neutrons, would be easier to work with. How true is that?
(The conceit of the story was that D-3 is hard to make on Earth, but that either Uranus or Neptune (can't remember which) had it in abundance in its atmosphere, somewhere on the order of quadrillions of dollars worth, so a private company sending out automated harvesters (it was a robot themed scifi anthology) was seen as a high risk, obscenely high reward strategy.)
It sounds like you're talking about Helium-3 instead of Deuterium-3. Deuterium-3 is actually Tritium, and is something already mentioned in the book review as something that we produce cost affordably on Earth by smashing neutrons into Lithium. Helium-3 meanwhile is more difficult to produce, and is a preferable fusion fuel to Tritium because using it produces no neutrons, which as other people are discussing would damage a Tritium fusion reactor and make it more expensive. People usually talk about getting Helium-3 from the Moon, not gas giants, which is probably why you remember the story talking about something other than Helium-3, but we will probably get the stuff from gas giants in the future because they have so much more of it than the Moon does. (More specifically, it's available in far greater concentrations, making it far easier to extract - you'd need to process something like 20 million tons of Moon rock to get a single ton of Helium-3, while gas giants would merely require processing roughly 100 000 tons of gas to get a single ton of Helium-3, a 200-fold improvement even before you consider that gas is easier to suck up with a vacuum than rock is to scrape up with a mining drill.).
As to what story you were thinking about... err, sorry, can't help you there. It sounds like it's relatively hard sci-fi though, since it's taking pains to skip over the common Lunar He-3 mistake, maybe that helps.
I particularly like how the profusion of 50%/70%/whatever probabilities sum up to success for sure. Clearly a techno-optimist with very little experience in the difficulties of realizing lab visions into systems that actually work commercially. For example: where is the author's personal experience in a community of estimated success actually yielding results? i.e. has the author's estimates of success ever been tested against actual outcomes?
Nor am I particularly impressed by the funding aspect. Let's take whatever was actually paid, in the author's graph, as actually representative (it doesn't seem like it which I will get into later): the cumulative spend in 2012 dollars for fusion research from the 1970s to today is easily $50 billion.
Large Hadron Collider cost $5B; Apollo program cost $25B - it seems we have long ago exceeded the "spend" the author blithely projects as necessary. ISS is $150B - but $50B cumulatively (note 2012 adjusted dollars) vs. $150B is not nothing.
Nor are government cost estimates to be trusted - the California high speed rail as well as programs like the F35 are monuments to something besides success in outcome as opposed to success in pork barrel.
Then there's the entire commercialization aspect.
It is notable that there are absolutely NO numbers for the cost of fusion energy, anywhere in the article.
This should matter, no? Just because you get more energy in than you get out, does not mean that energy is affordable. The cost of fuel isn't necessarily the driving factor - we have real world examples like nuclear power plants where the construction plus lawfare costs are so enormous as to materially impact LCOE.
So net net: I'd be happy of the author is right - but I will absolutely not hold my breath waiting for it - not the actual scientific/engineering achievement of commercial fusion energy much less the possibility of fusion energy replacing other sources.
"For example: where is the author's personal experience in a community of estimated success actually yielding results?" I'm not sure how you want me to establish credibility while being anonymous.
"Apollo program cost $25B." That is not adjusted for inflation. If you do, the price is over $200B.
"Then there's the entire commercialization aspect." It does matter. A lot of it is currently unknowable. The message of this review is that the science is almost solved. With successful experimental reactors, with the plasma close to power plant conditions, then we can get good cost estimates for commercialization. The construction and maybe maintenance costs will be dominant - the fuel cost is negligible.
Re: personal experience - if you have converted lab projects into actual working commercial prototypes, that would be at least an example of past experience without compromising anonymity.
Re: science is almost solved: I don't see this as a science issue to start with. I see this as an engineering issue.
If there aren't even experimental reactors yet present, then any estimates for success are purely guesses - at which point numerical percentages of success are completely misleading.
For example: the most common sci-fi problems associated with fusion have to do with the containment fields and the associated magnets. Maybe these are overblown or dramaticized, but it doesn't seem obvious at first pass that the pico- or millisecond fusion experiments in labs are truly testing the stability of containment over time. Instability issues are not time constrained engineering problems as the self-driving people are discovering.
@Fusion Reviewer: Why did the DOE pull funding from the MIT group that later formed Commonwealth Fusion Systems / SPARC? And, in fact, is that actually how it happened? From a google search, it looks like DOE *awarded* funding to Commonwealth Fusion Systems in 2019 https://federallabs.org/news/doe-awards-infuse-funding-to-brookhaven%E2%80%93commonwealth-fusion-energy-project . Are you sure it was that DOE pulled funding -> the group formed a startup, rather than the group formed a startup -> DOE gave them startup-funding money and pulled their academia-money? I have no idea how plausible any of this is, but I haven't thought of any other explanations for why DOE would pull funding from an MIT group but then give money to a startup of the same people doing the same thing.
(BTW I really liked this and was happy to finally stumble into a fairly short, readable, and accurate assessment of the current state of affairs! So thank you for the post.)
The DOE decided to pull funding from Alcator C-Mod (the experimental tokamak at MIT) in 2012. Congress restored its money for another few years. Alcator C-Mod shut down in 2016. Commonwealth Fusion Systems was founded in 2018 by many of the same people would had worked on Alcator C-Mod. The DOE has since given Commonwealth some funding, after they demonstrated their high temperature superconductor.
Why did the DOE decide to pull funding? So more money could be spent building ITER.
I don't know a lot about their design, so I don't want to make too strong of statements.
Compressing a plasma is really hard. NIF has spent more than a decade figuring it out. That being said, General Fusion's plasma is magnetized, so it doesn't need nearly as much compression as NIF.
The liquid metal vortex is made of lithium-lead. If the lead gets into the plasma, it will radiate out too much energy.
I wouldn't be surprised if some variation of the design could work. I expect that it will need several generations of experiments to get up to reactor level. They have one experiment already. I don't know what their best triple product is, and how many orders of magnitude they have to improve it to get to breakeven.
I'm glad I got to read this. It's a quantitative and specific introduction to the optimistic case for fusion power, with a book recommendation for those interested in learning more. But... it's not a book review? It's not any kind of review, really; it's forthright boosterism. Which is a good thing to have! Fusion energy is super cool and we should pursue it! And this post makes concrete claims that can help us understand and measure progress-- that's great! But I can't consider myself informed about fusion prospects just from reading this.
Like, as soon as I saw Figure 1, I thought to myself: this looks like the kind of stuff academics say to get funding for their projects. And the reviewer accepts this uncritically? Grant-writing, like political campaigns and Survivor, is a game whose sophisticated players expect that everyone including themselves is stretching the truth. The review's only acknowledgement that reality might diverge from projections is the offhand reference to a 20-year gap in the exponential triple progress trend as being due to needing larger reactors. (Why were they suddenly needed? And why did that need create such a discontinuity? The reviewer never explains.) I've also seen criticisms of the economic feasibility of fusion power on a variety of grounds (tritium production, facility requirements, power capture...) which admittedly are somewhat outside the scope of the review-- but I'd love to at least see them acknowledged and the risks quantified.
I won't be voting for this finalist but I was happy and interested to read it. As always, many thanks for contributing!
I've been following fusion since the 1960s when GE had an exhibit on it at the 1964-1965 World's Fair. It does feel closer than it did back then or in the 1970s with its energy crisis. In retrospect, we can see how some of the obstacles may have been removed by means of high speed computing, high temperature superconductors, high precision deposition machining, laser technology and a host of other technologies that didn't exist back then. There are obviously obstacles still to be removed. Back in the 1970s, I knew MIT physicists who were working on the problem, and in retrospect it feels like they were trying to fuse nuclei by rubbing two sticks together.
The 1964-1965 World's Fair was within a decade of the first tokamak, and before the Culham mission to Moscow. Things certainly have changed a lot since then !
Very cool primer of the state of the field, thanks for writing it!
I can't help comparing your bullish view of the future of fusion with the bearish one expressed by Daniel Jassby (formerly of the Princeton Plasma Physics Laboratory) in this recent article:
Personally I know nothing about plasma physics, but my understanding of Jassby's main points is:
1. Tokamaks like JET produce a mix of beam-thermal and thermonuclear fusion. Theory says that beam-thermal fusion is limited to Q<2. Thus, to achieve higher values of Q, tokamaks must transition to a design where thermonuclear fusion predominates. Is this an extra challenge that ITER must overcome, beyond being a bigger version of JET?
2. Jassby is also skeptical that the breeding reaction can produce all the necessary tritium in practice. He claims that Tokamaks would need external sources of tritium, which are difficult and expensive to obtain.
3. Based on a comparison of 2021 results from JET (tokamak) and NIF (inertial confinement), Jassby claims that inertial confinement holds more promise than magnetic confinement -- although it also faces significant engineering challenges. In particular, he argues that inertial confinement is better able to deal with issues 1 and 2 above.
4. He concludes that "the stark reality is that practical fusion-based electric power remains a distant prospect. It is likely unachievable anytime in the next half a century."
I cannot evaluate Jassby's claims, and don't know if his preference for inertial confinement is due to some personal bias. Thoughts?
I remain persuaded by Jassby and unpersuaded by this reviewer. Jassby has also written another good article that focuses more with the logistics and engineering challenges of converting fusion energy into electricity on a commercial level, which this review barely addresses.
Jassby's claims that magnetic confinement fusion (MCF) has stagnated for the last 25 years, while inertial confinement fusion (ICF) has progressed. I do not disagree: "There has been little progress towards a larger triple product since 2000." I think that this is about to change, while Jassby does not.
There is a simple reason why MCF has not progressed. In 1997, the best MCF experiment in the world was JET. In 2022, the best MCF experiment in the world is JET.
There's only so much we can do with JET's size and magnetic field strength. They could probably get up to Q = 1.5 if they really tried, but not the Q = 5 that you need for a power plant. Instead, JET has been focusing on other important goals like getting the walls right and increasing how long they maintain the plasma. As soon as we get a better experiment, we will get better results, whether it's SPARC or ITER.
It is true that computer simulations did not predict JET very well and underestimated the turbulent transport. Computational plasma physics is a lot better than it was in the 1990s, along with everything else involving computers.
Jassby makes a big distinction between beam-thermal versus thermonuclear fusion. I don't know of anyone else who cares about that distinction. His footnotes for it all point to papers he's authored by himself.
There isn't a physical difference between beam ions and plasma ions. An ion typically has to collide a few hundred times before it undergoes a fusion reaction. So by the time fusion occurs, the ions from the beam are thermalized and are indistinguishable from the ions originally in the plasma.
He also seems to use the terms to describe how the plasma is heated. When the plasma is mostly heated by the beam, then Q must be small, and when the plasma is mostly heated by fusion, then Q must be large, ... because that's the definition of Q. The causality is backward. "For a purely beam-thermal system, the maximum theoretical Q is limited to less than 2" should be "When Q is less than 2, the system must be primarily heated by the beam."
Tritium is very expensive. You don't want your reactor to have to import it.
Each fusion reaction consumes one tritium and produces one neutron. Each breeding reaction consumes one neutron and produces one tritium. It looks like, in order to sustain this, you'd need perfect efficiency, which is impossible.
Which is why we're also planning on including a neutron multiplier: beryllium.
Be + n -> 2 He + 2 n
This increases the number of neutrons, which allows the system to sustain itself with less then perfect efficiency.
Jassby does not think that SPARC is a game changer: "improving cost-effectiveness is surely a distraction for MCF research". I disagree. Cost effectiveness is important on its own. And it means that we can build more reactors faster. It won't take us 25 years to get the money together to build the next big experiment.
I agree that inertial confinement fusion has made a lot of progress recently: "Progress has been extremely rapid. They crossed Q=1 a few months ago."
The big challenge remaining for ICF is going from 1 shot per day to 1 shot per second. NIF is not trying to do this, because fusion isn't their main goal. Maybe Marvel or someone else will figure it out. I hope that they do ! But I suspect that this will be harder than getting fusion using a tokamak.
I liked this, and I don't care whether it counts as a book review. I'm happy to read the broader category "essays with a specific book as the occasion". I'm not as interested in this specific book as I am in fusion power, the thing itself; so why constrain the essay to merely summarizing and evaluating the book?
The alternative nuclear source is fission. Of which there is a limited supply, but also it is what causes geothermal heating, so there is still plenty. (And if you are OK with breeder reactors, well I think there is enough known uranium to last for a (~) hundred years or more. (Long term I'm going with more 'cause I'm betting we can find more uranium... or other stuff. (my son is in love with thorium... and salt.)
A book review on why fission is so expensive might be useful. (can I ask Zvi to do it?)
Can I still vote on this review if I'm pretty sure I know how you are? Give your pretty orange cat a lot of pats for me.
Like many commenters, I do think you underestimate the difficulty of going from engineering breakeven to economic viability: not so much the engineering problem, but the haphazard funding, the bad PR of anything nuclear, the regulatory mess, the lack of political interest in anything that takes >5 years, etc. Hopefully China will succeed, and the west will freak out and try to catch up.
IMO the crucial takeaway from the post is that plot: we haven't (so far) run into serious problems making fusion work, and we don't even expect to run into more than average, we just haven't had funding to try at all. I didn't know that!
OK let's say it all works out as you say and we get ready to build fusion power plants. What are the costs of those plants going to be and won't they suffer from the same regulatory laws for safety and such that keep fission power from being economical? Sensible regulations for fission (and fusion) plants seem like the most important step... Well and build Yucca mountain for waste storage.
They should not suffer from the same regulatory laws.
Nuclear fission reactors can meltdown because they have months worth of fuel in them at a time. There is a lot of energy that could be released at once. Fusion reactors will only have a few minutes or hours of fuel in them at a time, so there is no risk of meltdown. If a burning plasma suddenly stopped being confined (called a disruption), it could melt some expensive equipment, but it would not get out of the building. Since there is no chance of meltdown, there doesn't have to be as intensive regulatory oversight.
The long term radioactive waste that Yucca Mountain was designed for is spent fuel rods. Fusion does not involve any uranium fuel rods. No high level radioactive waste will be produced. There is some radioactive waste from a fusion plant. But this is much lower level and only has to be stored for tens or hundreds of years. It would probably be stored on site, not in geologically stable locations.
We try to keep the public (and regulatory agencies) from associating fusion too closely with current nuclear power. I would love to see a lot more nuclear power plants get built, but since the regulations there are not sensible, we want to stay distinct.
So disappointing that we have not made fusion a funding priority. It would change everything about the CO2 and climate change issues. The funding graph was an eye-opener.
A common criticism of the smaller experiment approach is that the heat flux through the walls of the machine would be too significant to prevent damage, and if your machine is too small it will just "melt".
Particularly, ITER was designed to support a heat flux on the order of 10 MW/m^2, whereas SPARC and others would be moving something on the order of 100MW/m^2 from the plasma through the walls of the reactor. A professor of fusion materials I spoke with told me that this makes small reactors impossible. Could I get some perspective or suggested reading materials as to why this might be wrong?
I know that the superX diverter can reduce this heat flux significantly, but as far as I know SPARC has not specified their diverter configuration.
I don't know what exactly SPARC is planning on using, but I know of several strategies that people have proposed to help with divertor survivability.
(1) Better materials. The material needs to both deal with the heat flux and it needs to not mess up the plasma. Heavy elements, in particular, get into the plasma and radiate out the energy too quickly. There are also proposals to coat the divertor and first wall with liquid lithium to both protect the material from the plasma and to protect the plasma from the material.
(2) The heat coming to the divertor is typically concentrated on a small area. If you can spread that heat out, it makes it easier for the material to survive. The superX divertor is one way to do this.
(3) Put a thin layer of gas between the plasma and the divertor. The gas radiates the energy out in all directions, instead of concentrating it on the divertor.
(4) Active cooling. Rapidly pump some fluid through the divertor so it carries the heat away quickly. This keeps most of the divertor cool, but you will get damage on the surface.
A power plant will probably involve some combination of these things.
I don't know of good references to get started with. Perhaps @Jason Parisi does? A few minutes on Google Scholar suggests:
I've done some research collaboration with SPARC team on exactly this topic. The primary reference scenario use fast strike point sweeping to spread the heat load. With sparc pulse lengths and thermal mass this *could* work, but will be pushing temperature limits of the materials and require longer time intervals between shots to allow machine to cool. They are also building capability for an X-Point Target diverter, which places an x-point at the end of the strike leg inside a semi-enclosed chamber. You get a benefit from increased wetting and surface area exposure, but in the ideal situation this would allow you to pump gas into the diverter and achieve full, stable detachment with minimal effect on the core. The goal is to test the XPT concept and see if it will work for the next bigger reactor that succeeds sparc.
I understand why everyone's complaining about this not being a book review, but to me the value of the ACX book reviews are not in their analyses of writing styles or authorship, but in the way they give me insight into topics and fields I wouldn't have looked into myself. Criticising the book's treatment is part of that, but I thought this review achieved that when it covered the research in the years since the book had been published. I enjoyed it!
i agree that scaling may solve some of the ratio issues, but am more intrigued by point elon brought up in his video about allegedly difficult to solve maintenance issues. Can tokamaks run continuously for years on end or is maintenance a pain? power plants that are in maintenance more than a very low single digit percentage of time are going to be difficult to manage.
Maintenance schedules are still mostly unknown. We need to have an experiment to get accurate estimates of the maintenance schedules.
We also don't know how fusion would fit into a broader electricity scheme. Would it function as baseload power or as peaker plants? Or maybe it would be something in between, filling in the gaps left by intermittent solar and wind? Baseload power plants need very low maintenance time. But peaker plants or anti-intermittent plants might not?
Thanks! Do you know where I could find similar without a worker inside but super high res, like do you know of any photographers that I could buy a high dpi printable version from? Want to get a big print for my wall :)
true true. i guess i have no idea how fast a tokamak can be turned on/off (or any clue about anything else on this topic really). My impression was that it must take a while to heat stuff up to these extreme temps but maybe not.
It takes about 1 second to turn on. A lot of the heating comes from turning on the magnetic field that quickly. To turn it off, flood the tokamak with cold gas.
Keep in mind, the amount of "stuff" that needs to be heated up, the total mass of the plasma resident in a toka/sphero/whatevamak, is a few tens of micrograms. Maybe hundreds of micrograms for the very largest. Apply a room full of high-power electronics to a hundred micrograms of stuff, it heats up in a hurry.
The limit for the actual fusion parts is set by the inductance of the ginormous magnets; those don't come to full strength instantly. As the OP says, on the order of a second. There's probably overhead issues like turning on the cooling pumps and verifying adequate flow that will take longer. And to get useful electricity out, you still have to deal with the lag times associated with large heat exchangers and turbogenerators. But, probably faster than any other steam plant, and maybe competitive with gas turbines.
If you want to turn it *off*, that can be almost arbitrarily fast, a few milliseconds if you need it. Again, modulo the fact that you'll have a turbogenerator needing to spin down and you'll break it if you try to do that part in milliseconds.
Eh. Great to see that at least the human race is at least kinda trying at the moment. But still, not a word on how we are actually supposed to extract reliable and safe energy from such a plasma, without the benefit of half a million kilometers of colder matter to shield us from its onslaught. Am I just supposed to fit some radiator tubes inbetween those super magnets? And I can somehow strike a balance between that fluid not becoming super radio active, and my reactor lining vaporizing / transmuting away, and contaminating my plasma?
I genuinely do not know if these are all trivial problems that have been solved 50 years ago; or if we are still so busy actually building plasmas, that we unironically have no idea how to get anything resembling economic utility out of them, once they are humming along. I fear the latter. I mean its easy to talk about breeder blankets and what not; but its another one to actually build one, and run a viable busines using one.
There are multiple proposed designs. I'll describe one of them here, called the "Pebble Bed".
Most of the energy comes out of the plasma as high energy neutrons. We want these neutrons to be absorbed by lithium in order to capture the neutrons and to make tritium. The neutrons' energy will be deposited in the lithium.
The solid surface closest to the plasma is called the first wall. It's job is mostly to survive and to keep high Z atoms from getting into the plasma.
Behind the first wall, there will be a layer a few feet thick filled with pebbles. These pebbles will be made of a neutron moderator, to slow down the neutrons, beryllium, which increases the number of neutrons so the blanket doesn't need to be perfectly efficient, and lithium, which absorbs the neutrons. Almost all of the neutrons should be absorbed by this layer so they don't damage anything behind it.
To keep the pebbles from getting too hot, a fluid flows through the pebble bed and to a heat exchanger. Helium gas has been proposed because it does not absorb neutrons and so does not become radioactive.
From the heat exchanger onwards, it's a standard steam turbine used to generate electricity.
A few of the pebbles can be removed at a time and replaced by others, so we can extract the tritium to use as fuel.
This is just one design. ITER will be testing multiple Test Blanket Modules with different designs to see which is best at absorbing neutrons, producing tritium, and transporting the heat.
The reviews were submitted as a Google Doc, so I used their equation editor. If I knew how mangled the equations would become, I would have written them like that.
Do you have a model for thinking about the commercialization of these achievements? E.g. how much will the first generation of power plants cost to build? Will they be able to charge below current natural gas prices? Solar?
So what you're trying to say is that fusion is 20 years away...
Hah, pull the other one!
Reaching net energy gain isn't the end there will still be a long way to go after that, like sorting out maintenance issues, and trying to bring costs down. I peg it as about 60 years away still and likely only useful beyond the inner planets.
I don't know very much about them, so don't trust my comments too much.
Talking about the pistol shrimp makes for a cool story.
I like that they have their triple product easily accessible on their website. They appear to have high enough density and confinement time, but 2 orders of magnitude too low temperature. This is unusual. Most techniques find it easier to get high plasma temperatures than high density & confinement times.
The biggest challenge faced by inertial confinement fusion at NIF has been in dealing with the Rayleigh-Taylor instability during collapse. To reach the best conditions, you need the pellet to collapse as spherically as possible. If the collapse isn't spherical, then the core will start to break up before it reaches the necessary temperatures and densities. NIF has put a lot of work into making their pellets more spherical and getting the light to shine in from all directions uniformly.
Unlike lasers which shine in from all directions and especially the X-rays from the hohlraum, collisions come in from one direction. They seem to have something that makes the shockwave bend into an arc. But this doesn't seem to me like something that can be made spherical to high enough precision. If you look at the simulations (2nd video on Targets page), it looks as though a lot of the energy in the shockwave doesn't make it to the target and that the shockwave isn't spherical when it hits the target.
Since this book review makes some explicit forecasts and this community is in general interested in forecasting: there are a bunch of questions on Metaculus pertaining to fusion. One of them pertains to "fusion ignition" (https://www.metaculus.com/questions/3727/when-will-a-fusion-reactor-reach-ignition/) . Unfortunately, there appears to be no agreement as to what fusion ignition means exactly (cf. my comment in the discussion there). Hence IMO the resolution criteria of the question are not ideal. I have tried my best to bring up some of the issues but I am a total lay person in this area.
It would be great if someone with actual expertise could weigh in there and also on the Wikipedia article (https://en.wikipedia.org/wiki/Fusion_ignition) on fusion ignition so that we can get better forecasts and knowledge dissemination on this topic.
The Metaculus question is poorly written. It gives two different definitions of 'ignition':
"If Q increases past this point, increasing self-heating eventually removes the need for external heating. At this point the reaction becomes self-sustaining, a condition called ignition. Ignition corresponds to infinite Q, and is generally regarded as highly desirable for practical reactor designs."
"This question will resolve on the date when a nuclear fusion reactor has sustained a reaction which produces more energy and heat than the external energy delivered to the system"
In the first definition, external heating is unnecessary and can be turned off. So external heat = 0 and Q = infinity. In the second definition, external heating is less than energy produced. So Q = 1. The first one is 'ignition', as defined by the magnetic confinement community. The second one is 'breakeven'. These are unlikely to occur at the same time.
The source of the problem is that inertial confinement fusion and magnetic confinement fusion use 'ignition' differently. The magnetic confinement community first started using the term for fusion. The plasma is assumed to be in steady state and is able to sustain itself with no external heating. Inertial confinement is never in steady state, so this definition doesn't make sense. Instead, their definition is that the amount of energy currently being produced by fusion in the plasma is greater than the amount of energy which is currently leaving the plasma. This means that the temperature of the plasma is increasing as the result of fusion reactions. This is not steady state, and the fusion will quickly burn through the fuel pellet.
To make this more clear, let's make a comparison to steam engines vs internal combustion engines. Steam engines have a fire going in steady state. You need to start the fire by adding heat. It only makes sense to say that a steam engine has reached ignition once it doesn't require any more external heat. It is then self-sustaining. Internal combustion engines have a fire only in small pulses. Each pulse requires external heat from the spark plugs. It is never self-sustaining. Instead, what happens is that combustion rapidly increases the temperature of the gas and burns through all of the fuel.
I don't think that ignition is the right goal for this question. Ignition probably isn't desirable for a magnetically confined fusion power plant. Even if we could reach ignition, we would probably run the plant at Q~30 because it gives us more control over the plasma.
It's better to avoid the term 'ignition' if you want to compare multiple very different approaches to fusion. Instead, define what you're talking about precisely in terms of Q. I chose Q>5 and steady state or 1 shot/sec as my criterion.
(Feel free to use this on Metaculus or Wikipedia.)
Every year I never cease to be amazed at how quickly humanity is developing. After all, every year people come up with more and more new technologies that allow us to optimize many processes and preserve natural resources. For example, the company smartenergy customer service https://www.pissedconsumer.com/company/smartenergy/customer-service.html operates, which produces electricity and does not harm the environment in any way.
I’m pretty sure fusion reviewer is actually Dr Bruce Banner.
https://en.m.wikipedia.org/wiki/Hulk
My joke when I was in grad school was that my job was "being one of Doc Ock's arms." After all, outside of Spider-Man 2, fusion researchers don't use complicated prosthetic rigs to run their experiments; that's what grad students are for.
I thought this was a no doxxing blog.
This is a technical puff piece for fusion; it is not a book review.
What facts are in error?
As an article for a lay person to understand the current state of fusion, I give this a 9/10.
As a book review, it's a 1/10.
Still appreciated and glad I read it, but it should be disqualified as a book review entry and just be allowed to stand alone as a primer on fusion and how close we are.
That's my thought. While often a good book review uses a response to ideas in the book as the seed for a broader essay (like the previous one on The Dawn of Everything did), this one didn't obviously rely on the book in any particular way.
Exactly my feelings as well.
I think the other negative for me is that the major point, which I take to be "fusion might actually be 30 years away", buttressed by the various high probability estimates, is kind of pulled out of nowhere. The only arguments I see are (1) all we ever needed was money and time, and (2) high Tc superconductors have made more experiments possible.
Those aren't bad arguments, but I would wish they could be fleshed out a little more. *Why* is so much money needed? (OK I can kind of start answering that myself, but it would be much better to have a pro read, and surely it must be covered in the book.) What are the nasty engineering or physics problems that have been overcome? That's not easy to do for an audience that may be intelligent but doesn't know all your vocabulary, but I'm told the book did it, so some of that could be laid out here, too.
Why is so much money needed?
Because the experiment needed had to be big. The two big bumps on the first graph correspond to "Build ITER" and "Build DEMO". It took us a long time to pull together enough money to build ITER.
High temperature superconductors allowed the experiments to be medium again, which decreased the cost by a factor of 10. We can now build a lot more of them, including from private capital.
The third factor is that China and Korea joined the game in about 2000. They've been spending more than anyone else and so are likely to finish their DEMOs (CFETR & K-DEMO) before 2040. I don't think that they're going to be first, so I didn't emphasize them as much, but they do provide more plausible paths to fusion.
There are nasty engineering and physics problems to overcome, but they aren't as important as the scale. And they take longer to explain than a book review.
I think you can do better. The experiment has to be big is just a way to rephrase we need a lot of money. You need to say *why* the experiment has to be big. Yes, I can at least start to fill it in for myself, but to make a connection to people who aren't familiar with the physics you need to tease that apart for them.
The larger the experiment is, the longer it takes for particles to move from the core to the outer edge. This improves the confinement time.
Explaining all of the relevant transport mechanisms probably takes too long for a book review, and is definitely too long for the comments.
Thank you for the advice.
About half of the book reviews in the New York Review of Books over the last half century would be disqualified by a requirement to be more about the book than about the reviewer's own ideas.
They have an implicit requirement that the reviewer artfully mentions the book or its author often enough to mask their own ideas as "commentary".
Next year, ACX should host a legit essay competition tier.
Is that a defense of this review, or a criticism of the NYRB?
This "book review" was plainly written by one of the authors or a close associate and is simply a summary of the book condensed into a blog post.
It shares the same fundamental flaw as the book: presenting some basic plasma physics and a bunch of lists of machines as if it were predictive policy analysis. Some PhD students decided to publish the first few pages of their literature review.
As far as I could tell, the technical content is correct. It is not necessary to fabricate facts to write a puff piece, it's a matter of picking the facts that provide a favorable spin to the story being told; figure 3 is a case in point, i.e., multiply some numbers to create exponential growth that can be compared to Moore's law.
I thought that I deflated the puff around figure 3 a few sentences later by pointing out that the trendline does not continue.
Pointing out that the trend line does not continue creates a sense of failure being snatched from the jaws of victory.
I was experiencing cognitive dissonance up to seeing this figure. These book reviews have been good/excellent/superb, and this was my mindset when starting to read. Figure 3 slapped me around the face and I suddenly saw the 'review' for what it was.
> multiply some numbers to create exponential growth
Lawson's criterion has long been used as a measure of how well fusion is working. It wasn't made up recently to make line go up.
Lawson's criterion is usually plotted with temperature on the x-axis https://en.wikipedia.org/wiki/Lawson_criterion
Nothing wrong with switching things around to show a different perspective. Adding in a line to show a comparison with Moore's law is great marketing copy.
This chart is also used in this paper (University of Technology, Sydney)
https://epress.lib.uts.edu.au/student-journals/index.php/PAMR/article/download/1385/1466?inline=1
Yes, I've seen things like this 30 years ago. When you are looking at something versus time, you tend to plot it as something per time.
There are not facts in error per se but the review still reads like a puff piece. Even if we solve the significant fundamental plasma physics problems, there are significant engineering challenges involved in fusion that are barely mentioned or brushed under the rug. These include the difficulty of effectively injecting tritium fuel, parasitic power consumption, proliferation risk, and radiation damage to the reactor itself. More on that last point: consider that DT fusion neutrons (14 MeV) are much higher in energy than fission spectrum neutrons (peaked at ~1 MeV). In other words, each neutron produced is capable of dealing much more damage to structural materials than in the case of fission. This issue is already a problem for fission reactors and will only be worse for fusion.
Of course, expecting all of these topics to be dealt with fully in a single book review is to set a high bar. However when the author makes strong claims outside scientific consensus (eg, giving Renaissance Fusion, who do not have even a prototype, a 70% achieving fusion by 2040) the burden of proof is on them.
I’m happy to see resources spent on fusion research. However the challenge must be tackled with a clear eyed view of the difficulty at hand.
Two estimates I've seen for the additional cost to adding intermittent sources of power put it at $40 and $50 per MWh above the base cost at 50% of production, due to transmission upgrade costs and idle backup generation. This goes up so that they didn't even make estimates above 80-90%
There is a large target for either low carbon baseload or energy storage that wind and solar can't reach as is, so that I see fusion as a good candidate. In particular it seems like there's no appetite for funding nuclear to the wider world due to proliferation concerns where there might be for fusion
$40 to $50 per MWh adds to perhaps 20 for the original power in PV in the US. That still makes it competitive with coal and natgas (~60), and much cheaper than fission (~100 to 120). So that's a big bar to leap.
There is absolutely no way any of the mainstream fusion designs discussed here will be cheaper than fission. Literally every single piece of the plant is more expensive and complex. Deuterium is not cheap, and the tritium is breathtaking even if we figure out how to breed it, which is an unsolved problem.
Even CFS puts the LCOE in the 200/MWh range for post-FOAK. We'll just build more batteries.
I live in California, land of wind and solar to the max, plus the highest electricity rates anywhere, increasing faster than anywhere else, and major reliability issues -- like planned blackouts because the solar power goes off just when the air conditioning and TVs go on -- so you will hopefully understand why I regard "proven" as more of an ideological than empirical statement.
To he fair, California has terrible regulation. Isn't eg net metering required by law?
California is a great example of why a reliable, clean, energy source is badly needed (I'm agnostic on "cheap").
But the way Fusion Reviewer sets out his stall, there's a hell of a long chain of "ifs" - IF public research gets government funding and IF private investment capital takes up the slack and IF ITER works and IF these other things work and IF we decide on what is the best design and so on and so on.
Other people in the thread are pointing out weak links in this chain. I get that he's an enthusiast (a fusioneer!) and so all his geese are swans, but criticism can't be brushed off simply by "you're a wet blanket".
Fusion is not intermittent.
If fusion is a good idea in the long run, then at some point, someone needs to invest in it.
I do think that we should invest in wind and solar as well. It is proven that they work at the scale we've deployed them, but not that they will work for 100% of our electricity. Mechanical energy storage solutions might work, but they have not been proven to work at the scale we need. Since there is uncertainty here, we should pursue multiple options.
If fusion is what we're going to end up using in the long run, we might as well get to where we can use it in the medium run too.
I agree completely, but if we could only do one form of energy resource development at a time, fusion would not be my choice.
FWIW, I'm a MarcorLife proponent, so my main interest WRT fusion is powering really large space habitats beyond Saturn's orbit. Fusion is clearly the best choice. Locally, though, I'd put more efforts into improved batteries and other forms of energy storage. (Solar heated molten salt has its points. So do various other options.)
OTOH, the original presumption is false. We can and do invest in more than one option at a time. I don't think we're over-investing in fusion.
All that said, while I found it a very interesting argument, I didn't think of it as a book review at all. (And I couldn't really figure out how to combine those "estimates of success" to derive a final "these are the odds". I don't really think those estimates are independent.)
Fusion is extremely intermittent. At present it typically happens for a microsecond, once every few weeks. This is just one of several rather intractable engineering problems with it.
Those other problems taken together make fusion unlikely to be worth investing in for any purpose other than curiosity.
Hi!
Re. why invest in fusion over other sources? My leading order answer is that I don't believe it's a dichotomy, and even if it were, it's good to not put all eggs in basket.
Re. climate change timescales and energy transitions, potentially, but you need low carbon base load. If you're (politically?) brave, you go for fission. If you're smart, you solve affordable fusion. I don't see many other options for base load unless energy storage and grid management improve a lot.
Keep an eye on SPARC in particular for faster fusion.
But yes, let's build 'renewables' as fast as reasonably possible.
To handle climate change you don't plan of fission or fusion power unless you're willing to handle a temperature rise of 2.5C+. They will/would take too long to come on-line.
What you do is really build out solar and wind (and other) sources of energy while at the same time really building out LOTS of separate storage facilities. I'm not a fan of Hydrogen, but if you overbuild the generation, you can use excess when you have it to generate fuel of some sort. (My preference would be a kind of gasoline derived from atmospheric CO2. That would be energy intensive, but you ARE dealing with an energy surplus.)
The high estimate for Renaissance Fusion is partly because I know them and am impressed by some of the ideas that they have not yet made public. I think that's my statement farthest from scientific consensus. Maybe my prediction for Type One Energy too. If you do downgrade these estimates, the headline prediction does not change by much.
The problems that you describe are real, but I don't think that any are insurmountable. The 14 MeV neutrons should be almost entirely absorbed by the tritium breeding blanket. The book has an entire chapter on proliferation risk. I have not looked into the other problems in detail.
Stellarators are perhaps the worst idea in fusion. Well, no, ICF is, but they're close.
Compared to a tok, they require dramatically larger numbers of individual magnets, the magnets (usually) have to be fantastically complex, the machine has to be built to a standard that is difficult to meet (to the point that NCSE was abandoned), maintenance is practically impossible, and their aspect ratio is absolutely terrible which leads to bad economics and really expensive tritium breeding.
The world's best stellarator currently posts numbers roughly equivalent to those being generated by toks in the 1980s. They have two orders of magnitude in triple product to meet current results. Crossing those two orders led to all sorts of unexpected new problems in the toks, which is why the graph flattened. There is no reason to suspect that the same will not happen in stellarators.
I'm not sure what secret sauce Renaissance claims to have, but it seems unlikely they have overcome *all* of these issues, especially the last one.
I don't know nearly enough about Fusion to declare it a "puff" piece, but I agree it isn't really about a book.
In fairness, last contest's Georgism review wasn't particularly about Progress and Poverty but rather about Georgism as an ideology, and it won.
The difference is that Progress and Poverty is a founding work of Georgism.
And the Georgism review was well-grounded *in the book itself*!
A couple of links to commentary on the state of play by others (neither paint as rosy a picture as this 'review')
https://inference-review.com/article/the-quest-for-fusion-energy
Sabine Hossenfelder 's take (her blog should be on everybodies rss feed)
http://backreaction.blogspot.com/2021/10/how-close-is-nuclear-fusion-power.html
Wow. What Hossenfelder writes isn't just a "not rosy" take, she's basically claiming the entire field of fusion research is fraudulent to the core. Having read that my interest in fusion is now sub zero. Assuming that's true and I see no reason why it wouldn't be, all government research for fusion needs to be cancelled, right now.
I mean, I think I'm a pretty average lay man with an superficial interest in fusion power, but I have known the difference between plasma break-even (which I think is the same as scientific break-even, Q=1) in OP and total break-even (engineering break-even, claimed to be ~Q=5 in the article, so 5 times as much) for a while now. This is explained in many articles I've encountered as well as in the OP, so it's not like this is some obscure thing that the fusion community is trying to hide from us.
Plasma breakeven is the same thing as scientific breakeven.
The same plasma can have different engineering breakeven, depending on how the rest of the experiment or power plant is designed. ITER should have Q=10, but not hit engineering breakeven. If you took off a lot of its diagnostics and didn't have four different ways of heating the plasma, then it probably could get engineering breakeven. But it wouldn't be as good of an experiment. We want to get lots of data about what the plasma is doing and we want to try out multiple versions of different subsystems to see which one works best.
The point here is that this "Q-plasma" take isn't something anyone cares about. Take the non-book-review, it says:
"We also measure the success of fusion using Q ... Q is entirely determined by the triple product."
That's the definition of Q-plasma to use Hossenfelder's (?) terms. For fusion to be a success in the way everyone else thinks about it means that it not only needs an "engineering breakeven" of >1 but it needs to have that with also a chance of being profitable ("financial Q") and relatively low risk to run the power plants. Note that profitability is so far from fusion researcher's minds it's apparently not even worth a mention in the article, have they even ever attempted to calculate this?
The issue here is that if fusion researchers really are defining success purely in terms of plasma energy balance, then how much effort can they be putting into researching all the rest of it? The article states clearly that "success" for fusion is as simple as improving Q-plasma. That's not a type of success meaningful in the real world.
And how can anyone defend the comments of the ITER guy?
"ITER will be the first fusion reactor to create more energy than it uses. Scientists measure this in terms of a simple factor—they call it Q. If ITER meets all the scientific objectives, it will create 10 times more energy than it is supplied with"
That is a directly misleading statement, isn't it?
I do mention profitability in footnote 7:
"There is also ‘engineering breakeven', when you get more energy out of the entire power plant than you put in, and ‘economic breakeven', when you get more money out of the entire power plant than you put in. We need to get scientific breakeven first."
There have been some people who try to calculate the profitability, but a lot of the relevant questions are unknowable until we build a full scale experiment. For example, there has been some discussion elsewhere in these comments about the maintenance schedules for materials exposed to 14 MeV neutrons. We won't know this until we get a good source of 14 MeV neutrons, which means we need a fusion reactor.
I would not have explained Q in that way. So no, I'm not defending those comments. They're also from an interview from 2006, which feels kind of cherrypicked. If you go to ITER's website, it says:
"ITER will be the first fusion device to produce net energy. [i] Net Energy: When the total power produced during a fusion power pulse surpasses the thermal power injected to heat the plasma." https://www.iter.org/proj/inafewlines
Bigot speaking to the US House is more concerning to me, because it seems less likely to be cherrypicked. It took quite a bit of effort to find the transcript of the conversation: https://www.govinfo.gov/content/pkg/CHRG-114hhrg20871/html/CHRG-114hhrg20871.htm
What we see in Hossenfelder's video is spliced - the question and the answer are not related. The question is from Grayson's opening statement. The response is from a discussion between Bigot and Foster about heat flux to the diverter. Bigot's quote continues: "It is materials, okay. When we will have continuous production of plasma energies, with some energy flux with neutrons which are as large as 20 megawatt per square meter". They are talking about the energy in the plasma and how it will impact the diverter, not the overall efficiency of the plant.
My take was that the research had been captured by people motivated by writing papers, not by creating something that generates electricity.
I think that Fusion can be made to work in practice, provided the time/money is invested to solve the unforeseen technical and social (e.g., team incentives) problems. And yes, it is probably still many decades away.
Your take seems to be compatible with a call to cancel funding for government fusion programs?
Private fusion efforts would still be worthwhile.
Governments are the only bodies willing to fund projects that require waiting several decades before anything tangible appears.
Funding is a known problem, but how do you incentivize people to work on a problem for their entire career?
Planetary scientists have it tough with a 10-year cycle to plan/build/launch a planetary probe, which is just a third/quarter of their career.
I think there's a lot of daylight between a certain degree of salesmanship, of which I think it's fair to say Hossenfelder accuses the fusion leadership, and an actual fraud (which she does not). Just think of the muddle between Q_plasma and Q_tot as the fusion equivalent of Tesla's "Full Self Driving."
There's still a serious issue here. ITER costs a crap-ton of money and time, and necessairly that means any *other* approach gets a little starved of oxygen. It's reasonable to be worried that this is not the right choice, although that has to be set against the possibility that there *is* no good choice that doesn't involved enormous piles of money and decades of labor. Reasonable men can easily disagree on the better way forward.
Not sure Tesla FSD is a good example - that one may well end up in litigation. Wouldn't be at all surprising if it did at least; selling features you can't actually provide will eventually get the courts involved. See: Elizabeth Holmes. And there are sure a lot of people upset with Musk lately.
The issue here is more that, once again, we find scientists making flatly misleading statements to government and the public and then hiding behind "oh you just don't understand our technical language". I'm getting real tired of this. It's reminiscent of the way that the word "unvaccinated" doesn't mean to Pfizer/public health what it means to everyone else, or how "record breaking temperature" also doesn't have the definition you'd expect when coming from climatologists. The public will learn to stop trusting scientists thanks to this kind of practice. Arguably that's already happening.
There's a simple fix: fusion researchers need to stop talking about break even as a concept. Being extremely generous and assuming it's not deliberate, their own project leaders are sufficiently poor communicators that they keep misleading the public about what "break even" means. Even the definition of "engineering break even" is pretty useless: nobody would describe a machine as break-even if it generates more electricity than it uses but requires fuel only found on Jupiter.
OK first of all, the public rarely hears from actual scientists doing actual work. What they usually get is science reporting, which works like this:
https://www.smbc-comics.com/comic/2009-08-30
Precise definitions of terms, and a carefully nuanced reporting takes a big backseat to "Fusion Real Soon Now! Rejoice!" or "Fusion: Giant Deplorable/Woke Fraud! Be Outraged!" in terms of page clicks, and those sweet sweet advertising dollars.
Secondly, people go *into* science in no small part because they don't *like* dealing with people, and aren't skilled wordsmiths, highly attuned to the implications and overtones their audience might take away. The stereotype of the scientist as a clueless one-dimensional dweeb who may fully grok quantum chromodynamics but gets tongue-tied ordering a sandwich is based in reality -- people who can *do* science are almost never very good at *explaining* it. And the people who have PhDs and end up doing a lot of talking to the public with some success are often a bit further from the front lines and drifting further away with time -- and develop their *own* concerns that are distinct from (1) understanding the science perfectly and (2) reporting on it dispassionately -- like, how's my new career as a science communicate going? How many "likes" are my Youtube videos getting? If they end up working for government then it gets even worse, because then it's also (3) is this going to play well/poorly with my politician employer?
Third, stuff like fusion (as well as a lot of other high-energy physics) is so expensive and labor-intensive these days that it's only done in teams of hundreds, massive collaborations. Under those cirx you don't have line workers talking to the media, you have a professional manager and professional PR staff, and for *them* their salaries are *all* about this particular project. You can't realistically expect the Director of CERN to give an objective evaluation of whether the LHC is worth the cost, any more than you can expect the CEO of United to speak objectively on whether it's better to Fly the Friendly Skies or take Ryanair and save a buck.
What investors learn rapidly, but which seems to strangely escape the Wikipedia generation, is that high-quality information is NOT FREE. It's not even cheap, it's very, very expensive, because it represents significant time and effort from somebody who is well-informed and skilled in the field. You want high-quality reporting on some issue that falls within my professional expertise, I'm happy to sell it to you, but my consulting rates start at $300/hour. Would you sell your professional skilled time for peanuts, or give it away? I mean, maybe randonly every now and then, as it amuses you, but on a regular basis you've got to pay your mortgage and all you've got to trade for dollars is your expertise.
So if you consume free information, be aware that the *true* customer for the reporting is not you -- it's whoever is actually footing the bill -- and adjust your expectations and skepticisms accordingly. If you want first-class accurate information, be prepared to pay beacoup for it. It's pointless to get mad at people who are enmeshed in the same economic necessities as the rest of us, and responding to the same signals and forces.
How does "record breaking temperature" not have the definition I'd expect? What's the actual definition?
Fusion research is plasma research. Don't expect anything more out of it.
Nah, Hossenfelder had good points but has now gone completely on the contrarian for contrarianism sake side. I used to follow her blog since 2013, i stopped some three years ago.
She's probably right on LHC successor but as an example her piece on Ligo and gravitational waves was bad faith nitpicking.
She definitely has gotten used to being a contrarian. And there is a place for contrarians in popular science.
Most of her videos are about cosmology or high energy physics. These fields have lots of people who communicate them to the public. Brian Greene and Michio Kaku come to mind. Having one contrarian among many popular scientists is often a good thing.
I don't know if she realizes how few popular plasma physicists there are. Her Youtube channel is much larger than ITER's (472K vs 63K subscribers), let alone Commonwealth's (1.7K). For a lot of her audience, this is the most they've ever thought about fusion. I don't like that the contrarian is the only voice a lot of people are hearing.
I agree that contrarianism has a place (boy, i am contrarian myself) but even in hep she is not the best critic around (i would say Peter Woit wins on that).
She nitpick something she doesn’t like (like the definition of Q in this case, or the way the LIGO experiment checked the electromagnetic counterpart) and blows it up beyond proportions to claim that the entire field is rotten. Between other problems, this also makes it impossible to make a good and fair criticism where needed.
Even at her best in hep, it's not like her criticism are particularly great. Naturalness in particle physics is definitely a failed paradigm and dissecting why it failed is crucial to move forward the field (and this is not being done by the community). However, I don't think her explanation for why it failed is correct, i much prefer Woit's argument (https://www.math.columbia.edu/~woit/wordpress/?p=12108), but admittedly that may be saying more about my biases.
Err, real science is all about nitpicking. If you're not nitpicking then you're not being rigorous, so if that's all you got for your assessment of her LIGO post, then it seems she proved her point.
On DT fusion, Hossenfelder's problem is she isn't contrary enough. The big problems with DT were identified 40 years ago by Lidsky (and Pfirsch and Schmitter); DT fusion reactors inevitably have horrendous volumetric power density, at least an order of magnitude worse than fission reactors. This issue has nothing to do with plasma physics and is not solved by high-Tc superconductors.
I have not yet read the first article. I have watched Hossenfelder's video.
Her main argument seems to be that she doesn't like how Q is defined and wants plasma physicists to define Q in a different way. Disliking someone's definitions is not enough to claim that an entire field is misinformation.
This is a bad faith interpretation of that article.
"In the technical literature, this quantity is normally not just called Q but more specifically Q-plasma. This is not the ratio of the entire energy that comes out of the fusion reactor over that which goes into the reactor, which we can call Q-total."
This is wrong. In the technical literature, Q is Q. Q-plasma and Q-total are terms that she invented in this video. I don't know of a single piece of peer review literature that uses her terminology.
> This is wrong. In the technical literature, Q is Q. Q-plasma and Q-total are terms that she invented in this video.
Yes, they are terms invented in this video to clarify what fusion researchers are actually talking about. They are talking about Q-plasma where we're actually interested in Q-total. That's exactly what she meant by this paragraph, so no, it's not "wrong", it's clarifying the confusion.
https://youtu.be/CnxzrX9tNoc?t=2849
From a recent video session Elon did at All In Summit. Not claiming EM knows this stuff best, but he seems clearly interested in the topic and would have had access to the people who know about this, and he would be looking at this from a practical/commercial rather than just scientific demonstration perspective.
Elon Musk doesn't think fusion is economically viable:
- rare fuel
- heat to electricity will lose lots of energy
- maintenance of the fusion reactor
He thinks wind power and solar power will be the future.
Elon Musk seems to have a cursory understanding of fusion, but hasn't looked into it in detail. Which is not surprising because we shouldn't expect him to be an expert about everything. He is both too optimistic and too pessimistic in different ways.
He says it's 100% technically possible because you just have to increase the scale. That's not how probabilities work: Would he take a million to one odds on that claim? Getting fusion is also not just an increase in scale. It's mostly an increase in scale, but whenever you make things bigger, there's a good chance that something will be different qualitatively too. This is why it's important to make progressively bigger experiments, instead of jumping from your first small prototype to a full scale reactor. Looking at the history of fusion, we have been surprised by both bad things (e.g. large turbulent transport) and good things (e.g. H mode) when we were just scaling things up. ITER and SPARC are designed for Q = 10 instead of Q = 5, so even if the experiment performs half as well as we think, it will still be good enough.
The rare fuel claim is interesting. Because it either means that he doesn't know about the tritium breeding blanket or it means that he thinks that it will never work. Tritium is very rare, but a fusion power plant should make all of its tritium on site out of lithium.
Transforming heat to electricity is done in most power plants today. I don't think it's a deal breaker.
Maintenance of the fusion reactor might be a serious problem. We don't know how much maintenance is needed until we have one running.
Putting these together, Musk thinks that fusion will cost an order of magnitude more than wind and solar. This is not outside the realm of possibility. But it's much too early to conclude that fusion will not be commercially viable.
Jassby's claims that magnetic confinement fusion (MCF) has stagnated for the last 25 years, while inertial confinement fusion (ICF) has progressed. I do not disagree: "There has been little progress towards a larger triple product since 2000." I think that this is about to change, while Jassby does not.
There is a simple reason why MCF has not progressed. In 1997, the best MCF experiment in the world was JET. In 2022, the best MCF experiment in the world is JET.
There's only so much we can do with JET's size and magnetic field strength. They could probably get up to Q = 1.5 if they really tried, but not the Q = 5 that you need for a power plant. Instead, JET has been focusing on other important goals like getting the walls right and increasing how long they maintain the plasma. As soon as we get a better experiment, we will get better results, whether it's SPARC or ITER.
It is true that computer simulations did not predict JET very well and underestimated the turbulent transport. Computational plasma physics is a lot better than it was in the 1990s, along with everything else involving computers.
Jassby makes a big distinction between beam-thermal versus thermonuclear fusion. I don't know of anyone else who cares about that distinction. His footnotes for it all point to papers he's authored by himself.
There isn't a physical difference between beam ions and plasma ions. An ion typically has to collide a few hundred times before it undergoes a fusion reaction. So by the time fusion occurs, the ions from the beam are thermalized and are indistinguishable from the ions originally in the plasma.
He also seems to use the terms to describe how the plasma is heated. When the plasma is mostly heated by the beam, then Q must be small, and when the plasma is mostly heated by fusion, then Q must be large, ... because that's the definition of Q. The causality is backward. "For a purely beam-thermal system, the maximum theoretical Q is limited to less than 2" should be "When Q is less than 2, the system must be primarily heated by the beam."
Tritium is very expensive. You don't want your reactor to have to import it.
Each fusion reaction consumes one tritium and produces one neutron. Each breeding reaction consumes one neutron and produces one tritium. It looks like, in order to sustain this, you'd need perfect efficiency, which is impossible.
Which is why we're also planning on including a neutron multiplier: beryllium.
Be + n -> 2 He + 2 n
This increases the number of neutrons, which allows the system to sustain itself with less then perfect efficiency.
Jassby does not think that SPARC is a game changer: "improving cost-effectiveness is surely a distraction for MCF research". I disagree. Cost effectiveness is important on its own. And it means that we can build more reactors faster. It won't take us 25 years to get the money together to build the next big experiment.
I agree that inertial confinement fusion has made a lot of progress recently: "Progress has been extremely rapid. They crossed Q=1 a few months ago."
The big challenge remaining for ICF is going from 1 shot per day to 1 shot per second. NIF is not trying to do this, because fusion isn't their main goal. Maybe Marvel or someone else will figure it out. I hope that they do ! But I suspect that this will be harder than getting fusion using a tokamak.
Why didn't you explain these interesting points in your 'review'?
A balanced discussion and explanation of the issues will likely have more impact than a blatant puff piece.
I explained some of these points in my review.
I didn't go into the details of particular current experiments like JET or particular subsystems like the tritium breeding blanket to keep the review from getting too long.
Sabine makes technically correct observations but they are generally less informative than the metrics she's criticizing due to scaling
ITER would have a Q-total of 1 with a Q-plasma of 10. But dial up the size and plasma powering so that the plasma has 80 MW of injected power instead of 50 MW and you increase power output by 5x as the reaction increasingly powers itself and you're talking about a net GW of electricity
There appears to be no commercial potential as it stands with ITER style tokamaks but last year a superconductor magnet was tested that doubles the magnetic strength. With current structural materials it should increase tokamak power by 10x for a given size, enabling commercial levels of power output that could be seen as possibly commercially relevant in price depending on developments
Basically at small experiment sizes the Q-total is overwhelmed by the facility size and at large sizes the relative information value of Q-total is overwhelmed by the rapid scaling potential. It's useful if you know things in some depth where if you don't I think Q-plasma is preferable
"Dialing up the size" poses its own significant engineering challenges. It's not at all trivial or obvious that it would be feasible anytime soon. I guess we'll see.
My model of last year's winner is:
(1) Pick a topic you know and care a lot about.
(2) Find the best book you can on that topic.
(3) Humorously but openly advocate for it.
There isn't a founding book on fusion like there is for Georgism. And I probably didn't execute this strategy as well Lars Doucet did. But I'm getting to talk to a lot of people about fusion and some people here like it a lot, so that's a success.
Well I loved it. I’m guessing there are a lot more out there that did, too.
I kind of like that some people use "book reviews" as a backdoor to make a guest post about something most readers will find interesting :)
If the NYRB is good enough for Freeman Dyson, it's good enough for me.
Right, as you go up the intellectual prestige level of book reviews, the the reviews become less and less tied directly to the book. At the daily newspaper book column bottom, reviews are about what the book has to say. At the New York Review of Books level, the reviews tend to be more about what the reviewer, who is an expert in the field, has to say about the subject.
Well, Scott will surely be flattered that you think ACX is closer to the New York Review of Books than the Daily Yell.
Yes, I think that's great. And there's a common genre of book review that does in fact review the book while doing this. This one was just a nice essay without really telling me much about the book other than that a plasma physicist thinks it's good and their parents think it's readable.
Agreed. This reads as one person's opinion on fusion in general, not a book review.
I have had a couple of looks through and I still can't figure out who the author of "The Future of Fusion" is, and now I'm stubbornly refusing to google it.
Jason Parisi & Justin Ball
“ Stellarators also have the best name, look the coolest, and are my favorite.”
It was worth my subscription just to get nuggets like that.
No thoughts on General Fusion or TAE? As an interested lay person, I like General Fusion's approach (Steam pistons! Liquid metal vortex!), and it seems like they've made substantial progress, recently settling on a site in the UK for a demonstration scale plant.
I'm in the Vancouver area so I hear about General Fusion all the time, but can never tell where they stand relative to others in making substantial progress.
I don't know a lot about either of their designs, so I don't want to make too strong of statements. But I'm skeptical.
General Fusion:
Compressing a plasma is really hard. NIF has spent more than a decade figuring it out. That being said, General Fusion's plasma is magnetized, so it doesn't need nearly as much compression as NIF.
The liquid metal vortex is made of lithium-lead. If the lead gets into the plasma, it will radiate out too much energy.
TAE:
They're using proton-boron fuel, which means that they need to make their plasma 10 times hotter and 10 times better confined than if they used DT.
Both of these companies have interesting designs for their experiments. I wouldn't be surprised if some variation of these designs could work. I don't think that they're particularly close to success, but maybe that's just because I don't know.
TAE has said they will licence their design for DT fusion if energy companies want to build them. However proton-boron seems so unlikely in a steady state configuration it feels reasonable to question their general assessments of their technology potential. I'd say the same about Marvel, we're basically counting on some radical laser developments though as far as I understand it's at least conceivable to do pulsed proton-boron with the effects of lasers that accelerate the target fuel so fast the energy transfer is non-thermal
I'd put General Fusion in the same boat as Marvel at least. They have good engineering advantages such as guaranteed excess tritium production and a fully liquid wall facing the fusion reaction
Despite Commonwealth Fusion System's top funding and reputation it appeared to me that their engineering problems were in need of a dramatic unknown advance to target a commercial electricity price so that the real medium term front runners were the Helions and General Fusions that need big luck in physics but could at least project commercially relevant prices. However it seems that has changed with a new simulation prediction that high power tokamaks will be able to double density or more, which could quadruple power. Now where you had a price per MWh of well over $100 for CFS ($260 for the original ARC proposal albeit not intended to be a commercially optimized configuration) vs Helion's $60 or lower it's now conceivable for tokamaks to be commercially relevant if there aren't major downside surprises for steady state high power plasmas
I don't think that Helion and General Fusion have an advantage over Commonwealth. Getting the physics right is usually a prerequisite for being able to estimate what the commercial electricity price will be. Helion's price estimates are a lot more made up than Commonwealth's.
General Fusion might be in the same boat as Marvel. I put Marvel higher because progress at NIF has been much better than I expected over the last 2 years. Using the wrong fuel is still a major problem for Marvel - if they succeed, I expect that will change their mind and use DT instead. General Fusion doesn't have a big national lab doing something similar to learn from.
Do you think that TAE needs to be aneutronic to make the geometry of their machine work, i.e., is it simply impossible to put an effective blanket around a colliding FRC machine, or are they merely pushing p-B11 because it's sexy?
I'd also like to hear your opinion on MagLIF. To me, it seems by far the most rational of the magnetized target experiments, and they seem to be making steady progress and have scaling that isn't obviously insane. Also, given the fact that it's a Sandia Z-Machine experiment, they get a fair amount of money for doing something that could eventually provide cheap fast neutrons for [CLASSIFIED] at a fraction the price that NIF requires.
Hi!
I think that a long term play of p-B11 fusion a-la TAE might make sense if they can conjure up some fancy physics (read, non-Maxwellian) to minimize radiative losses.
Potentially interesting:
https://www.princeton.edu/news/2022/03/10/fisch-receives-funding-unlikely-fantastic-clean-energy-technology
There seems to be a lot of negativity around this subject. My understudying is the science of this is accepted. It will work. The great difficulty is the engineering. This will be by far mankind’s greatest engineering challenge.
A lot of people will be upset if engineers solve this problem and the world continues on in energy abundance. How can we have Mad Max or some other dystopian future if engineers solve all the problems? Mankind must suffer!
For some it’s just healthy skepticism. For others it’s something else.
"De-growthers" are environmentalists who believe we need to reduce the economy and energy usage in general in order to preserve or restore the environment. They would be strongly opposed to cheap clean energy because of the "cheap" part: if it's cheap, then people will use it to make more stuff, mine more stuff, build more building, have more babies, etc. Which (they believe) will put more strain on the environment.
So some people would mind. Your average person, of course, would be very happy. But then again, the average person doesn't think life would be better if we had 1/10th the population and most people were farmers again.
Tbf, the argument that economic growth will make people have more babies has been empirically falsified and we can expect fertility rates to go down as GDP goes up. While the rates of mental ilnesses in us youngsters grows.
Which is the reason why I am a de-growther despite not being an environmentalist.
Energy abundance, and if you believe that, dear people, let me share with you this brown glass bottle full of amazing cure-all that will fix what ails you.
I'm old enough that I've been hearing about "this one weird trick will give us all energy abundance", be it nuclear power (electricity too cheap to meter!), solar power, and of course fusion.
Fusion is interesting science to research, and a clever trick if you can pull off the engineering. In twenty years time, it will still be interesting research on plasma, and clever engineering tricks to handle plasma. It will never be energy abundance for all. And no conspiracy theories about mysterious They who will be upset if engineers solve the problem will change my mind on that.
You’re really on point for a stereotypical naysayer. At its core you don’t want it to happen because it will upset your worldview.
I was reading a comment the other day that said, “What about the ozone hole?! That was fake. You never hear anything about it anymore.”
The reality is there was an ozone hole, they banned CFCs, and now it’s repaired itself. There was a big problem and we fixed it.
Certain folks get upset about that because it’s just so anticlimactic.
Less of this, please.
Am I wrong and these people don’t exist? I could be.
It doesn't matter whether you are right or wrong, because this isn't the correct way to respond to somebody either way; it is unkind and unnecessary, given that there are kind alternative ways of expressing the same general idea.
Ok. What would you have said to express the same sentiment?
I don't know, the response seems reasonable enough.
Some guy is describing fusion advocates as claiming that its a "magical" technology, and this comment is what you take issue with?
(1) I'm not a guy
(2) Kindly learn to distinguish rhetorical hyperbole from actual claims; why do you think I put the "magical technology" bit in inverted commas?
(3) I am not questioning the science qua science, I don't have the expertise to do so. The timeline sketched out seems very optimistic, but who knows?
(4) What I *am* questioning is the starry-eyed extrapolation to how this will change the world. We've seen plenty of promises of huge world-altering changes, and how many of them worked out the way they were intended? Fusion may well be a solved technology and we never adopt it on a large scale because by 2040 we have something else we're using. Please untwist your knickers about someone wondering if this time, this big promise is going to end up just like all the other ones.
"We've seen plenty of promises of huge world-altering changes, and how many of them worked out the way they were intended?"
I'd guess maybe 10% ?
GPS works. Weather satellites work. Integrated circuits and optical fibers work...
Yes, _lots_ of things don't make it off the drawing board, and _lots_ of things don't make it past the prototype stage but, depending on how tightly you want to define "world-altering", there are at least dozens, and probably hundreds, of technical innovations that worked.
There is a reason to be more optimistic than this, because there's a new, mature technology that changes the game substantially: high-temperature superconductors.
More specifically, rare-earth barium copper-oxide (REBCO) tape is available commercially from several vendors, and it gives you roughly double the field strength at liquid-hydrogen or -neon temperatures instead of the liquid-helium temperatures required by ITER's magnets. This makes the magnets cheaper to build and operate, and allows the machine itself to be about 25% the size of ITER, which makes it much, much cheaper.
It's a game-changer. It's not a slam-dunk game-changer, but it's enough of one that the traditional "fusion is the power of the future and always will be" joke is now way closer to glib than it is to profound.
That said, there are plenty of things that can go wrong. The most important of those things is that SPARC, the reactor that Commonwealth is building, is still an experiment. It's not designed to be a commercially viable system. Indeed, they've made an interesting choice to trade machine life for earlier operation. So if they really do get to Q=10-20, then there's still a whole bunch of engineering to do to get to ARC, the machine that could be at the heart of an economically viable power plant.
I see you're also using the "by the time fusion arrives, what we're using for capacity will be a done deal" argument. But that argument is only true if you expect renewables to replace fossil fuels and then grow at a very sedate pace from there on.
I doubt that's going to be what future demand looks like. Indeed, I suspect that the successful mitigation and remediation of climate change will require expending energy in profligate amounts. Want to do atmospheric carbon capture at high scale? It's a massive power hog. How 'bout desalinating and lifting enough water to support agriculture in the Punjab--or Nebraska? What if you need to refrigerate the bottom of a glacier to prevent teratonnes of ice from sliding into the sea?
I'd like to plan on the world needing one or two orders of magnitude more capacity than dumb extrapolation would indicate. That requires another old cliché from the early nuclear age: power too cheap to meter. Maybe renewables get you there. But I want a few hedges against that. Fusion needs to be one of them, and it needs to be funded aggressively enough that it's not a joke.
I disagree. Deiseach's comment was sufficiently snarky and devoid of substantial arguments to invite a response like BronxZooCobra's. At least the latter actually included an example in which scientific and engineering progress, paired with political will, fixed a real, serious, global problem.
Less of this please
"At its core you don’t want it to happen because it will upset your worldview."
Come back to me when you get out of nappies, kid. I've been to this dance before, and it's never worked out like the techno-optimists have promised us it was going to work out.
Given that I am *constantly* scrabbling about looking for cheaper utility plans because the centres where I work *eat* electricity to run and we're on a tight budget, I would fucking *love* if somebody gave us cheap, clean, abundant energy.
You know what happened the last time there was a great plan to do this? Solar panels on the roofs of the buildings (including the building where one of our centres is located) in a new build project, to help cut down on heating costs because instead of oil and electricity, water would be heated by solar power.
You know how it worked out? Awful. First, this is Ireland - we don't get enough sun reliably throughout the year to generate enough solar power to boil a cup of tea. Second, when we got freak sunny conditions, it was *too* sunny and the panels exploded and had to be replaced.
So the "here's a cheap, clean, efficient energy source" green wishful thinking that was funded and built in all sincerity was a dismal mess. I have no reason to think fusion is going to be the one time there is never a problem and we all end up with our own personal jetpacks to fly us to the lunar tourist resorts.
“ I've been to this dance before, and it's never worked out like the techno-optimists have promised us it was going to work out.”
It hasn’t? It’s 94 in Houston and for almost everyone it’s 72. For hundreds of years the biggest killer was Tuberculosis. When was the last time you heard of someone dying of TB? For hundreds of year one of the great toils of women was laundry - girls used to not go to school on Monday’s as that was laundry day. They would spend the day at grueling backbreaking labor.
I just threw a load in earlier today and it’s done.
"When was the last time you heard of someone dying of TB? "
Funny you should mention TB, or were you unaware it's coming back as a major disease?
https://www.mirror.co.uk/news/uk-news/health-warning-one-person-dies-27262263
"One person has died after contracting tuberculosis in the UK, as a leading health body issues a warning.
Three people have been diagnosed with TB after they came into close contact with a student who died with the disease in a Welsh town.
The University of Wales Trinity St David student died in October 2021."
https://cordis.europa.eu/article/id/436505-fighting-the-spread-of-tb
"Tuberculosis is preventable and curable, and yet 9 900 000 people fell ill with the disease in 2020 and 1.5 million died. This episode is looking at what the EU is doing to curb the spread and improve our understanding of the nature of the illness."
So yes, baby boy, people in this the 21st century *are* still dying of TB. Don't teach your grandmother to suck eggs.
So no matter what great advancements are made you’ll be a naysayer. Is that fair to say?
If I mention that Ireland has gone from one of the poorest countries in Europe to one of the richest you’ll bring up every negative you can think of rather than celebrating that great triumph.
And obviously I meant dying of TB in a first world country like Ireland.
And that you’re trying to argue that tremendous medical advances haven’t been made…
What's with all the ad hominem? From my outsider's perspective it looks like you're being very condescending and smug here. You can make your point without constantly calling someone a baby.
I think that laundry story is a myth. Laundry was much difficult in the past therefore we did much less of it. Today we spend the same about of time on it because we wash every piece of cloth everyday. This partially confirmed by my childhood experience when I lived in frugal conditions (ex-Soviet country), sometimes even without electricity and washing machine.
Indeed people would wear clothes many many more times before washing them. It absolutely was a huge chore, but people weren't spending 8 hours a week doing laundry.
“ it's never worked out like the techno-optimists have promised us it was going to work out.”
He says via a system of electrical impulses that are converted to pulses of light that flash along hair thin strands of glass under the ocean to propagate his thoughts to thousands of people around the world.
"a system of electrical impulses that are converted to pulses of light that flash along hair thin strands of glass under the ocean"
We got the first reliably working undersea cable in 1865, so try a little harder to impress me on that front, daddio 😀
https://en.wikipedia.org/wiki/Transatlantic_telegraph_cable
We have personal and business drama from over three thousand years ago, because of data storage:
https://en.wikipedia.org/wiki/Complaint_tablet_to_Ea-nasir
(The entire Ea-Nasir saga is wonderful, I'd recommend reading up on Some Real History That Really Happened:
https://www.tumblr.com/blog/view/mostlydeadlanguages/656166624810991616?source=share)
Technology is wonderful. Human nature, however, doesn't change. Impress me with your shiny space colony fusion future when the people inhabiting it aren't bitching about so-and-so has nicer quarters, better rations, or access to fifty-seven genders as social identities and I'm confined to only forty-six.
"Impress me with your shiny space colony fusion future when the people..."
That, by the way, is why I don't think space colonies are feasible until they are governed by an AI, and we have a vastly improved sociology. And probably also a vastly improved virtual reality. Until then we'll need to have small groups with strong bonds holding them to the home planet. And I still think that's what we should be aiming for.
OK, but you need to be aware that nobody predicted that years in advance. They predicted other things that didn't happen. Predictions in a complex area are almost always wrong, and when it's got chaotic resonances and strange attractors...well, the predictions are often WILDLY off, even if many of the details are correct. E.g. read "True Names" by Vernor Vinge. (That may have inspired the Matrix movies, but that's a guess.) Now compare it to on-line chat groups and other similar phenomena.
There are no black swans because I’ve never seen one.
More of this please.
Is there any substance to this comment beyond "this will never happen because it would be too good"?
Besides, the examples you cite are not actually terribly supportive of your point. Nuclear energy didn't give us energy abundance essentially because we decided not to build it. Solar energy is _currently_ growing and getting cheaper at astonishing rates, such that the main obstacle now is storing and transporting it, not generating it.
"Nuclear energy didn't give us energy abundance essentially because we decided not to build it. Solar energy is _currently_ growing and getting cheaper at astonishing rates, such that the main obstacle now is storing and transporting it, not generating it."
You have answered your own question. Right now, fusion is at the "it will be fantastic magic out of nothing clean cheap infinite energy!" hype stage (and has been since the 70s and possibly before, but I can't remember anything before then).
Nuclear power was going to be the same - and then, as you said, we decided not to build it.
Solar/renewables were going to be the same - and then we ran into "crap, we can generate it but can't store it for even and sufficient supply".
Why do *you* expect the development of fusion will run any smoother and without obstacles bobbling up? As to "there are a lot of people who will get upset if we get cheap clean abundant energy", does anyone else get the "we have the technology to let cars run on water but Big Oil is suppressing it" vibes?
>You have answered your own question. Right now, fusion is at the "it will be fantastic magic out of nothing clean cheap infinite energy!"
Describing fusion as being based on "magic" is bad faith. You're unfairly trying to make them seem unreasonable by using BS terms to describe their claims.
>Nuclear power was going to be the same - and then, as you said, we decided not to build it.
Because it was too expensive to build it to be safe enough. Unless similar safety issues requiring very expensive engineering controls will be present for fusion reactors, then fission being too expensive to build is completely irrelevant to fusion's potential.
>Solar/renewables were going to be the same - and then we ran into "crap, we can generate it but can't store it for even and sufficient supply".
Again, unless this describes a problem that fusion will also suffer from, IT'S IRRELEVANT.
>Why do *you* expect the development of fusion will run any smoother and without obstacles bobbling up?
Because the issues with other power sources are not conceivably an issue for fusion. The burden of proof is on YOU to demonstrate that problems will likely exist. Otherwise, no new technology ever has any hope of working because something completely different in the past didn't work.
Not sure about some of that. Fusion certainly has the potential for radioactivity problems like those that plague fission power -- anything that generates MeV neutrons is going to have *that* and fusion neutrons are even more energetic than fission neutrons. We don't know yet what those problems will be, and how easy/hard they will be to solve, because nobody has yet built a practical fusion reactor. But they aren't simply absent because of the technology.
>Because it was too expensive to build it to be safe enough.
What killed it was the ALARA standard, which defines "safe enough" as "maximum safety possible at the same price as existing power stations" and therefore "enough spent on safety that it's not worth building". Sane definitions of "safe enough" (e.g. "safer than coal") weren't too expensive at all.
"Sane definitions of "safe enough" (e.g. "safer than coal") weren't too expensive at all."
If a coal mine in Cumbria catches fire, that does not affect me. If Windscale/Sellafield goes ka-blooey, that does affect me (based on what way the wind is blowing) and I don't even get the benefit of the power it generates. "Nuclear power plant goes up in flames" is a hell of a lot more dangerous than "underground coal fire".
I don't expect that commercial deployment of fusion will be rapid and unhindered. In fact, I'm not even a fusion partisan - I don't know whether it'll work or not. What I'm taking issue with is you staking out the position "this definitely won't work well enough to cause dramatic improvements" and basing it on some combo of "we haven't had something this good happen yet" and "there will be issues to deal with along the way".
Those claims, though true, aren't a meaningful argument about whether fusion will have a major impact because they apply equally well to any energy source you could imagine. Unless there's some iron law of nature that applies, arguments that treat the particular facts as irrelevant details are insubstantial.
I am with you on this. Fusion energy might work but the social aspect will not be simple.
I compare this with covid vaccinations. We were not sure if the vaccine will work, but then it worked. Not perfectly but reducing risk of death about 10 times was great and we should have returned to pre-covid society in about March-April 2021 when the elderly population was vaccinated.
It didn't happen for some reason. It wouldn't have happened even if the vaccine was 95-99% effective and sterilizing. Politicians would still obsess with restrictions because the risk was not 100% eliminated and so on.
We are unhappy society not because we don't have abundant clean energy such as fusion. Fusion is an interesting scientific/engineering problem but the issues we deal with is only 5% about the lack of clean energy.
Actually, I'd but the issues at over 50% due to a lack of abundant clean energy, but that would be soluble. It would be expensive, but we know several ways to handle it. We could even do it with giant mirrors in the desert that melt special salts that we then use as an energy store. So lack of a way to deal with it is not the basic problem. There doesn't seem to be a willingness to deal with them, because doing so would require small short-term sacrifices to ensure long-term flourishing. But people over-discount the future. (And, truthfully, often the people who benefited would not be the ones making the sacrifice.)
I think the reason we are not building those giant mirrors in desert that the society (some rationalist geeks excluding) don't think it needs them.
I personally think that would be a cool thing but the problem is to sell the idea to others, especially policy makers. We need good story tellers, really good ones in fact. I think that's why I like Scott. He is a geek who can also tell stories.
If[1] fusion works, I'm sure some people will object to it enough to stop it in their communities. But unless they can stop it everywhere, including China, the future is still coming.
[1] I'm not sold on the if yet
It depends on specific details with the new technology – cost, environmental impact etc.
Right now I hear a lot of arguments from greens that nuclear power is bad not because of radiation but because it costs too much and is not profitable. Wind and solar is much cheaper and don't need to develop anything else. The countra-argument that we need to ensure base-load is hard to make because it is hard to wrap in a good story.
Nuclear fission didn't yield energy abundance because the downsides to building it were too high. The goal was never *just* energy abundance. People assumed that there wouldn't be huge downsides. It's also quite expensive to run the (current) plants in a way approximating safety.
OTOH, I've read SF from the late 1930's and early 1940's. When they assumed that energy abundance was feasible, they didn't assume that this would lead to anything even approaching idylic lifestyles. Often they assumed to opposite, though you didn't get things like Heinlein's "Blowups happen" until after the end of the war. But if you were getting "energy abundance" and "energy too cheap to meter", you are/were believing PR puff pieces. (Most of them by companies trying to ensure continued government funding.)
Heinlein's "Blowups Happen" is a short story from the 1940s about the boss of a nuclear power plant going insane from the high risk.
In general, golden age science fiction authors tended to assume that disasters would happen (e.g., in Heinlein stories there are usually unexplained references to "New Chicago" or the like, leaving it up to your imagination what horrible thing happened to old Chicago). They tended to assume the public would keep the same appetite for risk-reward tradeoffs, not realizing that people would become more safety conscious (e.g., swimming pools used to generally have diving boards but they don't anymore).
The one area where elites haven't got much more safety conscious is advocacy of bicycle riding, which is popular to encourage despite it becoming relatively more dangerous over the course of my lifetime as others things have become safer.
I'd be interested in why ITER is in France. I'm guessing it's related to why France relies so much on nuclear power: because France has an old fashioned modernist powerful centralized state without all the local checks that, say, California has that slows down construction by adding a whole bunch of levels of veto.
"Blowups Happen" assumed there wasn't any way to make the power plants safe. So much so that the only answer was to put them in orbit. When you say "Golden Age" I'm not sure whether you mean pre-war or post-war, but after Hiroshima the mood was very different. Heinlein started to move away from advocating nuclear power ("Life-line") and Poul Anderson wrote "Tomorrow's Children" to name just two.
> Is there any substance to this comment beyond "this will never happen because it would be too good"?
It's not that fusion won't happen because it would be too good, it's that even if it does happen it won't be as good as you think. Fusion won't be the free energy panacea everyone seems to be selling.
This is literally not an argument. There's no substance to it whatsoever.
Fusion is categorically different to fission. The fact that fission has not lead to energy abundance is irrelevant. The reason fission is so expensive is the engineering required to make it (excessively) safe. Fusion is not dangerous in the way the fission is, and so this cannot be the economic failure mode for fusion.
There are very clear arguments for why fusion will/could/should lead to energy abundance. If you're unwilling to engage with them, you shouldn't be making a post against them.
People have made bold claims about energy abundance before - this is irrelevant. Fusion is very different to these things, so simple minded appeals to analogy are not valid. If you have a *specific* reason for why fusion won't lead to energy abundance, fine, make it. But this comment is exactly identical in spirit to declaring that heavier than air flight can never work, because look at the thousands of failed attempts in the past.
I'm seeing a lot of "wah-wah-wahing" for my refusal to accept "but *my* technology is different!"
I hope I can make you understand - all the arguments you are pooh-poohing right now ('well, fusion was *never* gonna be at the races') are *precisely the terms in which the fusion argument is being presented*.
Fusion will/could/should lead to energy abundance? Heard that before about nuclear. Now you are telling me fission is *completely* different (which I accept on a physical level, yes it is) and that is why it never fulfilled all those promises. But fusion is going to do it.
Look, I can't speak to when fusion is going to be a solved problem. It may well happen by 2040 or 2050. But Shiny New Abundance World? Merely solving the technical aspects is not going to bring that about, which is what I am trying to point out. We *have* experience of "as soon as we get the bugs worked out, this will solve all our energy needs!"
And has it happened like that? Are electric cars solving the problem of gas prices going up and people being discontented for the midterms? Are we zooming around to our lunar resorts? Yes, I'm pouring cold water on the Shiny New SF Future.
I would love to have it. I *want* the Shiny New SF Future I was promised as a kid in the 70s. So much of the far-flung era of the 21st Century was going to be way different because Science!
And now we're back to 70s stagflation, price increases at the petrol pumps, and you lot in the USA can't even feed your babies due to a shortage of baby formula. And we have Russia in another war of aggression.
Tell me how "this time it's different" and I'm a science denier. I'm not denying the science, I'm denying the social and political extrapolation from it. "If we solve fusion we will get cheap abundant energy". Maybe. And maybe not. I asked why countries didn't engage in fusion research, and got told "Oh well, maybe the Cold War?"
If we're going to be demanding specific reasons, I want a better one than "fusion scientists were too pure-minded to engage in politicking". Maybe countries didn't pour money into it because the game wasn't worth the candle.
And don't try and convince me that past bold claims about energy abundance before are irrelevant, when you are using the same pitch to persuade me that this time, there *is* a pig in that poke.
Try zooming out a little bit. Capitalism and technology have, in fact, solved all the world's problems if you take a longer time frame and look at the right metrics.
Sure, but if that argument is highly persuasive, then it suggests things like ITER are folly. We should just let capitalism and technology solve the problem of the most efficient energy generation scheme, and stop trying to use government to force one particular solution.
Why limit our options? The public sector and the private sector should *both* be working on this. If success comes about through the free market, great. If success comes about through the state, also great. Yes, too much government spending can disrupt the market and reduce its overall efficiency, but ITER spending is just a few hundred million per year out of a $5 trillion budget - it's not going to tank the economy. The internet was developed through a mixture of public and private funding, and the same could very well end up being true for fusion.
"Are electric cars solving the problem of gas prices going up...?"
Yes. For anyone who has one.
Nuclear power has certainly been a disappointment—though it does produce a ton of clean energy and will for decades and decades—but if fusion fails as badly as solar power we *will* have energy abundance. Solar has gotten incredibly cheap and abundant over the last 20 years. You're also old enough that you will have heard stories about impending energy disaster for your entire life—peak oil, etc. Technological advances, not just in renewables but in energy efficiency and even the discovery and production of fossil fuels, have made that seem ridiculous over and over.
To be clear I don't think there's any "mysterious They" keeping us from fusion, though it certainly seems like we should have been spending more given the potential rewards. But the idea that we haven't solved a bunch of big problems since you were young is simply not true, so it's not a good heuristic for deciding whether some future technology is plausible.
I'm a car guy, and future-energy stuff makes me think about cars anyway, so for example (and I know you're not from the US, but those are the stats I know)—in 1969, when we landed on the moon and before standup comedians could conceive of asking where our flying cars were, 5.19 people died per 100 million vehicle miles traveled in America. In 1987, when I was born, that was 2.42. In 2021, that was 1.33. At the same time cars have become more fuel efficient, dramatically faster, etc.
Likewise, in my dad's lifetime (1948-) we've gotten "too cheap to meter" wrong, and he always kids me about it because he knows I love reading about nuclear power. But we've also basically wiped out polio (2000 US deaths the year he was born), measles (400 or so), and rubella (last epidemic in 1964-5 apparently caused 11,000 fetal deaths and 2100 neonatal deaths). Even COVID—we certainly could have done much better, I think, with better trial processes, and the death toll has been awful. But also, within a few months of the first community spread of COVID in my area I was in a trial receiving what turned out to be an extremely effective vaccine for it. That's incredible! And people who held themselves out as a realistic level-headed experts *at the time* were saying that it was going to take twice as long, or three times as long, or more.
I know none of this is news to you, obviously, but I just don't see how the last 40 years would make you think "energy too cheap to meter" is a uniquely impossible dream to achieve.
I think we all believe in progress, but progress per se is not a good argument for the odds of success of any particular technological push -- not when history is absolutely littered with the corpses of technological pushes that failed.
Yes, human beings will probably continue to advance technologically for quite a while. But will that progress be represented by achieving practical fusion power generation? Maybe, maybe not. Progress isn't uniform. We tend to make breakthroughs in random areas, hard to predict[1], and advance amazingly in one direction while not much else happens in others. Maybe progress in this century will be amazing in fusion, or maybe it will be in some other area -- maybe someone will produce an effective vaccine against breast or prostate cancer, and a terrible scourge will be vanquished, and then arguments in the future will be like "we beat breast cancer, isn't that amazing? so why don't you believe we can develop a warp drive/fusion power/some other techno miracle?"
----------------
[1] A cautionary tale here is the fact, mentioned in the review, that high-Tc superconductors were a game-changer for fusion. But nobody was doing research into superconductors *as part of* fusion research, because nobody had an idea that much higher Tc could be achieved at all. It was a surprise. But that's kind of how science works. A lot of time, the key advances you need happen in fields you didn't expect, and so it's hard to plan for them and *especially* hard to put them into a budget and deliberately create them on a schedule as part of a "throw money at the problem until it's solved" approach.
To be fair, though, while fusion is likely a pipe-dream and so is limitless energy in general, I don't believe that mere energy abundance is an impossible goal. It might not be achieved via fusion, but it can be reached via a combination of various technologies, such as solar, wind, tidal, geothermal, and of course nuclear. We have all of these technologies today, we just need to invest in them -- or, in case of nuclear power, stop banning them. There are also productive engineering projects to be developed, such as improved nuclear reactors and orbital solar collectors.
The major problem with all of these is that it would require a massive investment a la the Manhattan Project to significantly improve energy availability... and I do not believe that any Western country has the ability to do that anymore. China has the ability, but not the desire -- they're fine with coal.
I suspect the issue is overloaded definitions of "energy abundance". Some hear that and imagine you are proposing "post-scarcity".
Suppose we get energy abundance, the price of electricity drops to 1/1000 th of current rates (or lower), everyone has an electric car that doubles as a portable battery.
No doubt we will find some amazingly wasteful ways to use energy, and then face bunch some other limits (battery material precursors become expensive, ditto for conductor metals for the distribution to end-users, or maybe there will problems in scaling the ability to reprocess used batteries to match the production [1], some environmentalists are bound to oppose solar and wind farms, ultimately there could be issues with dumping all the excess heat from all the appliances everyone is running). The energy abundance might happen, but it is a real possibility it won't be an experience of plenty ... any more than our current way of life is.
What we did with the abundance of compute cycles? Price of MHz has gone way down since the first microcomputers. The Allies had years of money and person-hours in compute effort to crack the German military codes. Today probably you could have a novelty screensaver to do it. But does it feel like in post-scarcity compute utopia?
Everyone has a smartphone and spends a lot of time on internet. Yet the high-end computing experiences are still very expensive. If you can get a VR headset, you are certainly above median income. If you can finance (out of your own pocket) enough TPU hours to train a custom GPT-4-sized language model to produce the best AGI memes for your personal fun, you are certainly a millionaire.
[1] Think of the 19th century fear of "peak horse manure" problem.
There will never be "abundance" in the sense of "too cheap to meter" - there are just so many things you can do with large amounts of energy that the cheaper energy gets, the more we will demand, and we will always be operating at the frontier.
However, it does seem likely that there may well be "abundance" in the sense of a return to the growth rates of energy use comparable to those of the 1950s and 1960s. In the 1970s, there was a slowdown in overall energy use growth (along with a million other things) as the oil crisis hit. Since around 2000, total energy use has stagnated, as coal and oil started being phased out for gas and renewable. Even without fusion, if renewables can continue their exponential growth after coal is done phasing out, then we already get substantial energy growth until gas starts phasing out. With fusion, there's a good chance that continues even with gas phasing out.
https://en.wikipedia.org/wiki/Energy_in_the_United_States
You’re exactly correct.
I don’t recall why likes aren’t allowed. It seems valuable to poll the commentariat as to the validity of a given argument. Our host is a fan of prediction markets. Maybe we can pay per like? It’s not a true prediction market but we can say “I really think this is true.” And $.05 goes to our hosts favored effective altruism.
That's a fun idea, but he's using the Substack platform, and since this doesn't sound like an idea that many other Substacks would want to use, they might not want to go through the work of implementing it.
Also, I should share the link to Noah Smith's Substack post that got me thinking about energy abundance - I'm not sure if this is a re-blog of that post or something else related: https://economics.enlightenradio.org/2021/12/noah-smith-on-energy.html
When I was age eight in 1967, 55 years ago, the L.A. Times began running a Sunday comic strip about science. It's first ever topic was "Fusion Energy Is Coming."
Do you think the idea of the cost of electricity going down by a factor of, say, 20 is more implausible than the transition from not having electricity at all to having it in the first place? If so, why?
What exactly do you mean by "the cost of electricity going down by a factor of 20"? Do you mean "cost of generation" or "total cost of your electricity bill at the end of the month/bimonthly billing period"?
Because I could see costs of generation going down, which of course is going to have an effect on the total of the bill. But costs of generation alone are not all that comprises a bill. I don't know how American bills are calculated, but here's a sample of an Irish bill - and please note, there is a temporary reduction of VAT from 13.5% to 9%:
https://www.youtube.com/watch?v=QtRqq1atQ-8
Under the old VAT rate of 13.5%, the total cost of this bill would be €149.43
Cost of electricity at €0.258 unit price (and that's not a standard price, it depends on your tariff) less discount = €78.61
Cost of add-ons (Standing Charge, PSO levy, and 13.5% VAT) = €70.82
Total bill: €149.43
Suppose cost of electricity plummeted to €0.052 unit price, the new bill would be:
Cost of electricity = €17.32
Cost of add-ons = €55.39
Total bill: €72.71
That is a great reduction, but as you can see, the greater part of the bill is still not the electricity cost as such. And depending on the running costs of the fusion plant and costs of getting the generated electric into the grid, etc., the add-ons might even be increased to cover the cost.
So "cost of generating power via fusion drops", sure. But maybe "cost of building, paying off debt on building, return of profits to investors and shareholders of fusion plant + other extras rises", as well.
IMO mankind's biggest problem right now (aside from our own human nature) can't be solved by energy abundance. The issue is that we're fouling our own nest, and making the planet unlivable. Sure, it'll help if we stop burning so much fossil fuel, but that's not the only thing changing the climate and killing off the biosphere.
With infinite energy we don’t have to live here.
Imagine how much cleaner our "nest" will be when we can afford to put all our heavy industry in space!
There's a hell of a lot we could do with abundant energy to make things better. You also haven't described 'the biggest problem', you've described hundreds of smaller problems and lumped them all together. There's nothing that can solve all of these problems simulteaneously, so the fact that fusion powered energy abundance can't solve them is irrelevant.
"Sure, it'll help if we stop burning so much fossil fuel, but that's not the only thing changing the climate and killing off the biosphere."
It's not the only thing, but an abundance of cheap energy could easily help to mitigate a lot of the other problems too. Energy can be used to get rid of waste, after all. Energy can also be used to make all sorts of processes (not just energy generation) more efficient so that they generate far less waste to begin with.
"Things that could theoretically be done with electricity instead of fossil fuels" covers probably 80-90% of greenhouse gas emissions - that's not a small change. And the industries that can't directly be replaced by electricity (e.g., livestock emissions) can still be handled in principle by throwing energy at carbon capture projects.
Lab-grown meat is energy intensive. I think they'll get there if they're willing to use real animal meat as necessary to complete the jump over the uncanny valley, but the animal footprint could be reduced by an order of magnitude.
Mankind's biggest problem right now is CO2 emission. This is a problem that can be solved by non-fossil energy abundance.
I don't actually think that people will be upset if many of our problems are solved by technology. I think that a lot of people just see problems that stem from political/societal issues (e.g. global warming would be eminently solvable if governments cared and would coordinate, but because they don't/won't, it's a huge mess) and feel intuitively that they have to be solved through political/societal battles. It's actually kind of tough to have the intuition that instead of winning or losing a fight about those issues, we may just stop needing to fight due to quantitative improvements!
That’s what I’ve been trying to say…far less eloquently. Thank you!
While it's about fission, not fusion, I think this New Atlantis piece explains fairly well why laypeople are disinclined to trust "the science" when they distrust the mediators implementing the science:
https://www.thenewatlantis.com/publications/democracy-and-the-nuclear-stalemate
In the abstract, I'm irritatingly techno-optimistic! But I've also accumulated enough bad encounters with the gatekeepers of all this wonderful, life-enhancing technology to find myself, rather against my will, growing increasingly distrustful that it will benefit "people like me" when "we" need it.
Take, for example, the humble X-ray. X-rays are amazing! Sometimes they've benefited me. But they've also been used to justify denying me timely care, needlessly harming assorted body parts. I know the X-rays themselves weren't to blame. The problems were with human judgment: X-ray being the wrong tool to rule out a likely problem; wishful thinking in interpreting X-rays to avoid the liability of treating someone pregnant... I didn't have unmediated access to X-rays' diagnostic power, but access mediated by someone whose job it was to know better than I how to use this wonderful technology, and who, for whatever reason, didn't do the job promised.
Reassurance that fission *can* be made safe doesn't necessarily inspire trust that it *will* be made safe if a fission plant is built in your neighborhood. Technical reasons for fusion plants to be more feasible still wouldn't address various social and political aspects of feasibility.
Supposing we did build a fusion-fired power plant, would people worry about it exploding like a giant boiler if something got clogged, "taking out the neighborhood"? I don't know that it would "take out the neighborhood", but steam explosions still kill people, and steam driven by what could be summarized as an artificial sun does sound extra-feisty. Even if laypeople were persuaded that fusion isn't the same radioactive danger fission is, would they trust the whole apparatus, steam and all, to be sited and maintained properly so that they're not the ones "punished" by a fusion plant going "boom"?
Can laypeople trust whoever's in charge to use technology appropriately around them?
“ Reassurance that fission *can* be made safe ”
It is safe. It’s incredibly safe. It’s only not safe if (among other things) you discount the lives of every coal miner who died of black lung. And that’s just for starters.
I don't discount those lives. Or the other stuff you allude to. I'm pro-nuclear-power. Grateful to live in a world where it's possible.
I'm also pro-X-ray. I've nonetheless accumulated experience suggesting I can't trust X-ray diagnostics to be used correctly on me. I still chalk that up to "random bad luck" or "maybe I *am* that poor of a patient advocate for myself." But it gives me more sympathy for someone in a LULU (locally unwanted land use) neighborhood who hears, guess what?! Our LULUhood's the lucky winner of the new fission plant! We're reassured that, all around the world, fission plants chug along safely and cleanly (which, yes, they overwhelmingly do), so *of course* the one planned for neighborhood will... even if previous LULUs didn't turn out so well for us.
As I understand it, a lot must go right to ensure the fission plant design that's currently dominant runs safely. We have the technology to ensure it does go right! And usually the conscientiousness, too.
Usually.
Yeh. But then I hear there are anti-wind turbine protests in Europe. Ok, you don’t want wind, you don’t want solar, you don’t want coal, you don’t want nuclear and you don’t want Russian gas, fine. You’ll just have to freeze to death in the dark come winter.
We don’t want that most of all!
If by "you" you mean the impersonal "you", rather than me, specifically, I get what you're saying. If you mean me specifically, I moved to a LULU to get a better deal on housing.
Perception snaps into schemata based on experience. One schema is "modern technology has had phenomenal success saving and improving lives, including poor and powerless lives" (which is true!). Another is "LULUs are LULUs for a reason" — and in neighborhoods with a history of suffering due to LULUs, "others benefit from modernity by dumping its dangers here". I doubt which schema wins is entirely under people's conscious control.
"If it's so safe, why won't the ritzy neighborhoods take it?" invites the logical rejoinder, "Why waste money building it on such expensive property?" but it wouldn't surprise me if the example of wealthier, more powerful neighborhoods volunteering for these projects were more persuasive to holdouts than the fact of general gains through technology. YIMBY!
A miner dying of black lung is terrible, but that death does not kill me off hundreds of miles away.
"Ooops, our beautifully safe steam turbine had a one-in-a-million accident" may, if I'm living close enough to it.
You may not remember, but I do, the effects of the Icelandic volcanic eruption.
https://en.wikipedia.org/wiki/2010_eruptions_of_Eyjafjallaj%C3%B6kull
Actually the coal plant likely has significant health impacts on you because its emissions are incredibly harmful. Everywhere more coal plants open infant mortality rises, as does asthma, cardiovascular disease and a bunch of other things.
"We see massive differences in the death rates of nuclear and modern renewables compared to fossil fuels.
Nuclear energy, for example, results in 99.8% fewer deaths than brown coal; 99.7% fewer than coal; 99.6% fewer than oil; and 97.5% fewer than gas. Wind, solar and hydropower are more safe yet."
https://ourworldindata.org/safest-sources-of-energy#:~:text=We%20see%20massive%20differences%20in,hydropower%20are%20more%20safe%20yet.
There's some more specific info in there and it's sources, especially Burke et al and Lockwood et al:
https://www.sciencedirect.com/science/article/pii/S2666759220300706
Like, it's scary something might blow up unexpectedly and kill you, but if we replaced all coal with nuclear total life expectancy would go up, disasters included. It's similar to comparing flying to driving. I'm not sure if you have any particular hangups there, but the argument is really similar. Flying is saver than road tripping to your destination. But people are afraid of flying because the rare air crashes are really bad and kill lots of people. But risk is likelihood multiplied by impact.
I dunno. If I take a look at my latest electricity bill, only 25% of the cost is listed as due to the cost of generation. 75% is distribution and taxes and bond payments and whatnot. So if fusion reduced the cost to generate electricity by a factor of 10 -- which seems darn optimistic -- then my electricity bill would be reduced by about 20%. That's not nothing, but it doesn't fall into the category of "enegy too cheap to meter" or some such.
I thought the main argument for why fusion power is nifty is that, like fission, we don't produce pollutant gases or have to pay for expensive scrubbing tech, don't produce a crapton of CO2, and don't have to stripmine Wyoming to get the fuel, but unlike fission we don't have as much high-level radioactive waste and don't worry so much about people building nuclear weapons with the same tech. These are all defensible goals, but they're not really related to the economics of power generation.
That’s a good point. The thought is that if energy is cheaper then concrete is cheaper, copper is cheaper, steel is cheaper, etc. If those things are cheaper, if the fundamental quanta of energy in our civilization is cheaper*, then vastly more things are possible.
A world with abundant energy would not have the same transmission costs as indicated by your current bill. A fusion civilization would not be on the same Kardashev scale as our current civilization .
Yes, I'm aware of economics. I'm just pointing out thatin tthe economic component (my electricity bill) that has the *highest* proportion of its cost going to generation, the amount isn't actually that high. The impact on the price of concrete or copper is necessarily going to be even less.
Anyway, I don't disagree that cheaper energy is better. Economic efficiency is always a win, except maybe cheaper high-quality cocaine, not sure that was a good thing when it happened a few decades ago.
I do think to be taken seriously one would need to make a good case for *why* fusion energy would be so very much cheaper than any other type. Where's the giant savings coming from? Not from simpler and cheaper to build power plants, clearly. Low fuel costs? I mean, maybe, water is cheap, but deuterium is not, although fortunately you need very little of it.
But the story of nuclear fission is cautionary: *that* turned out not to be cheap, despite the fuel costs being minimal. So one would have to make an argument why the entire generation cost, soup to nuts, fuel plus capital and operating costs of the physical plant, regulatory and cleanup costs, environmental costs, et cetera, all work out to be way way cheaper. Haven't seen that argument yet.
I don't really see why transmission costs would disappear. If anything, I would expect them to be higher. A fusion plant is *such* a complex and expensive piece of machinery that economies of scale would suggest you just build one or two for the entire United States, have them generate TW of power, and distribute it everywhere. That's how nukes worked out, after all: it turned out to be better to build a great big one, which could generate massive watts at a minimal $/watt ratio, and then pipe it around.
“ I do think to be taken seriously one would need to make a good case for *why* fusion energy would be so very much cheaper than any other type. ”
Scale - solar will never make getting you to orbit cheap. Fusion can. You can’t think in terms of your energy needs now, with current technology, you need to think of “your” energy needs 50 or 500 years from now.
Yes, scale is not a bad argument, but again we get back to the point that 3/4 of my energy bill *right now* is distribution, because we already kind of use scale in electricity generation -- that's why we have all these enormous towers and transmission lines going thousands of miles. So we need to understand why scale, which is already being used pretty heavily, hasn't at all reached the limits of its potential.
I'm not seeing how fusion helps me get to orbit cheap. The problem with getting to orbit is that I need to generate a lot of kinetic energy *but* I also need to generate it quickly (high thrust) *and* I need to generate it on board a flying vehicle (so the tragedy of the rocket equation). How does having gigawatts of electricity available for cheap on the ground help me out? Are you thinking some kind of railgun approach? I put all my kinetic energy into my orbital vehicle on the ground, then let it blaze (literally ha ha given friction in the lower atmosphere) to orbit?
Liquid hydrogen and oxygen are very effective and very expensive as a method to get you to orbit. If there was a technology where we could cheaply crack water and then condense the resulting components, that would be a big deal.
This is just a random example off the top of my head.
You’ve read this?
https://economics.enlightenradio.org/2021/12/noah-smith-on-energy.html?m=1
If you're going to claim fusion will get you to orbit cheap, you need to be more explicit. Perhaps you're thinking about a laser-powered first stage? I've seen speculative designs that don't look implausible, but also aren't really convincing. Or perhaps you're thinking about something else, but it sure isn't clear what. It won't give you a cable good enough for a space elevator.
Right. The obvious wrong answer, per many generations of science fiction, is that we're going to fly to orbit using fusion rockets or "drives" that are vastly more efficient than chemical rockets. And maybe in the 23rd century, we'll be doing that - but none of the fusion technologies discussed here are remotely practical for earth-to-orbit propulsion. The power-to-weight ratio is going to be far too low, and the power comes in the form of relatively low-grade heat in the neutron-absorbing blanket that is difficult to turn efficiently into rocket thrust.
Fusion-based systems may have some utility in deep space transportation, where very low but continuous thrust will suffice. That's actually part of Helion's backstory, among other things. But it won't get you off the ground.
And while you can envision using "too-cheap-to-meter" fusion power to run beamed-power propulsion systems, or electromagnetic launchers, or to turn water into liquid oxygen and hydrogen, that's solving the wrong problem. As others have noted, the *energy* costs of space launch are a tiny fraction of the total. It's hardware and operations costs that make space travel ridiculously expensive. If you come up with a system that works, you can get the power from the current grid just fine.
I don't think it's going to just be "10% off your electric bill"[1] but "there are a whole bunch of new ways we can use electricity that we didn't think of before." People who hauled water up from wells by hand would never consider daily showers or water parks.
Matt Yglesias has a bunch of articles at Slow Boring about energy abundance.
[1] I don't know off-hand what proportion of my electric bill goes to just the labor for maintaining the grid but it more than doubles during the summer months so I know it's not just 25%.
Well, we'll see. I'm still missing the part where electricity becomes fantastically cheaper because it's produced by fusion instead of fission, or burning nat gas, or even rooftop solar. The capital costs are admittedly enormous, the operating costs (skilled labor, upkeep and repair) look to be pretty darn expensive, at least as much as operating a fission plant, and we're looking at if anything higher distribution costs because it's inherently a lot more centralized than something like a nat gas plant -- we're going to need still more transmission lines and all the associate switching and load balancing hardware, which all needs its own upkeep. Nobody is going to be dotting the countryside with 150 million K operating temperature tokomaks which require the kind of precision and care in assembly that goes into a chip fab or fission reactor.
I get that water is very cheap, but tritium isn't, and it's a bad time to be competing on the world market for lithium (plus natural lithium is only about 5% Li-6 if memory serves, so you might need expensive isotope enrichment), so while you need very little of the fuel stuffs it doesn't feel any more economical than fission fuel.
As a technological achievement is seems extremely cool, and it would be good to have some more options for power generation, but I'm just not seeing how this is going to make electricity -- from start to finish, from funding the capital construction costs to delivering it to the end user -- just amazingly cheap. It feels a little uncomfortably like an Underpants Gnome theory of energy abundance:
1. Fusion breakeven achieved!
2. ????
3. Energy too cheap to meter, changes world.
I totally agree with (3) but it's (2) that has me a little skeptical. I hope the problems are solved, I'd love to live in a world like that, but...it would take more than I've heard to persuade me it's definitely on its way.
No, the great difficulty is the materials.
Engineering challenges go away if you throw enough money at them. The Manhattan Project was, primarily, an engineering challenge.
Materials challenges are potentially intractable because the material doesn't exist. You can throw all the money in the world at high critical temperature, high critical field superconductors, and still not wind up with any. Because they don't exist.
Hello everyone !
I just made this account so I can engage in the conversation, while still being an anonymous reviewer. I will try to answer all the questions I find in the comments.
I have invited Jason Parisi, one of the authors of the book, to come as well.
Thank you !
Hey, my biggest issue with this is defining "getting fusion" at achieving Q>5 in steady state. I am fairly confident that SPARC will get Q>5, and I think they'll get there by 2025 as planned (with maybe a year or two of slippage), but this is a long ways off from getting us to economically or climate relevant fusion energy. I'm wondering why you chose this metric for your predictions?
Basically, I think it would make more sense to forecast ARC than SPARC, and I think the odds of ARC working conditional on SPARC are maybe around 30-50%.
Once we get to Q > 5, we've effectively solved the scientific problem of fusion. Ignition (Q = infinity) only requires about twice the triple product as Q = 5 and we would probably want to operate a power plant below ignition (maybe Q = 20) to have more control. At this point, fusion becomes an engineering / economic / regulatory problem instead of a scientific problem.
That's not to say that the other parts of the problem aren't challenges. But I think that they are solvable challenges. I would probably say 80% chance that it there's less than 5 years between SPARC hitting Q = 5 and ARC. ARC here being the first fusion reactor that sells electricity to the grid.
Most of the engineering problems have to be solved to get Q = 5. Between SPARC and ARC, Commonwealth will still be economically functioning like a startup. Startups live on hype rather than profit, and I expect that hype will not be in short supply. Getting from ARC to mass produced fusion reactors that can compete with other energy sources will be harder. I don't know what the regulatory environment will be, but hopefully not terrible in at least one country.
"At this point, fusion becomes an engineering / economic / regulatory problem instead of a scientific problem.
That's not to say that the other parts of the problem aren't challenges. But I think that they are solvable challenges."
I'm less sanguine about them being _affordably_ solvable challenges. The 14 MeV neutron material damage problem looks hard. The tritium breeding problem looks hard. I've heard magnetic confinement fusion designs described as looking more like an LHC particle detection experiment than like a power plant. Thay have expensive, delicate, parts, and it isn't clear how often which parts will need to be replaced.
Getting to Q=5 will be an extremely impressive achievement. I will be the first to congratulate the team that succeeds in reaching it. I agree that the scientific problem will have been solved at that point. Given the amount of deuterium and lithium available to us, we will basically know at that point that we have fuel for a million years.
But we will _not_ know, at that point, whether we have _affordable_ fuel for a million years. It might still be the case, after reaching Q=5, that a better choice might be any of thorium/U233 fission, or solar plus storage, or solar plus (possibly global) transmission.
Then there's the personnel problem. If Igor Kurchatov and Andrei Sakhorov had been operating Reactor Number 4 at Chernobyl the night of 26 April 1986 the world would never have heard of the place. But it was being run by schmos, because you can't afford to have briliant PhDs running a power plant.
A fusion power plant needs to be able to be safely and economically run by trained apes. That's not a trivial challenge.
True! But a fusion power plant doesn't have the ability to have a runaway reaction like Chernobyl did. It _does_ produce neutrons, as you've noted elsewhere, but there is no equivalent to positive-temperature-coefficient-of-reactivity that blew the 1000 ton cap off the top of the Chernobyl reactor. We could have a plasma-instability-wrecks-inner-wall-of-vacuum-chamber, but that is more at the billion-dollar-property-damage level of tragedy, not nearby-city-plus-exclusion-zone-abandoned-plus-fatalities level.
Sure, but we can't dismiss the property damage aspect of this. People are certainly more valuable than dollars, but dollars are still valuable. Let's say you build a $50 billion fusion plant that can supply the entire Eastern Seaboard with electricity, and it starts doing so, and some asshole operating the plant closes Switch B under operating conditions X, which maybe his training didn't quite cover as emphatically as it should, and would have been obviously wrong to someone with a PhD in plasma physics -- and our beautiful fusion plant is wrecked, shazam, nobody killed thank God but will cost $15 billion and 10 years to repair.
For sure potential *investors* would be thinking about that scenario. And it's worth thinking about. Look what happened to Boeing when they figure they could do something inherently less safe in the 737 Max and rely on pilot training to compensate. (And it *did* compensate, at least in First World major airlines with comprehensive training, cream o' the crop pilots, et cetera.)
You can afford to have ordinary PhDs running them,since physics PhDs are being overproduced.
Conveniently, the 14 MeV neutron problem and the tritium breeding problem are the same thing. But it's still a problem that is potentially too difficult to solve affordably. The best way to figure out how often things need to be replaced is build one and see.
It's possible that fusion won't be the most affordable option for a while. But I do think that we should try to get it there.
Fair enough. That seems reasonable.
I'm fairly worried about the engineering challenges. Tokamaks are just very complicated, there are many parts that can break, many non-trivial challenges we haven't solved, and challenges with operating continuously that we do not have a lot of experience with.
But yes, I agree that once SPARC works, there will be a lot of hype, and that will generate funding, collaborators, more talent, and so forth that will power the more abstract flywheel. This is one of the major reasons for me own optimism.
Your writing ability is phenomenal! I’m very impressed and I wish to subscribe to your substack. (I’m totally serious.)
Thank you !
I'll be anonymous until the competition is over, then we can talk.
Have you read this article: https://inference-review.com/article/the-quest-for-fusion-energy ? He also presents himself as a fusion expert, but gives the opposite impression as you- a very skeptical, pessimistic view of the field.
It's a long and detailed article, so I don't completely understand it. But my takeaways were:
1) Those record Q factors for tokamak/magnetic confinement listed on your graph were *transient*, all-time highs that lasted only for a split second. The record from 1997 has never been matched, and the latest results (after two decades of improvement) are actually lower than that.
2) Their roadmaps and rosy predictions for the future are mostly based on computer simulations. Nothing wrong with that, except that tokamaks have a history of not being able to physically match what their computer simulations.
3) To achieve performance, they (tokamaks) have heavily relied on juicing the plasma with imported Tritium. Tritium is expensive and basically only produced by a handful of aging nuclear reactors, all located in Canada, with concerns over nuclear weapons proliferation. There has been little to no progress on getting a reaction from D-T "burning plasma" which would be necessary for a self-sustaining operation.
4) inertial confinement designs have performed much better in recent years, both in terms of Q and in using Deuterium instead of relying on Tritium. But of course they only last for a split second, not enough to generate any useful energy even if they had Q above 10.
5) That all the fusion "startups" and mini reactor projects have so far mostly failed to produce any fusion reactions at all, let alone anything that would justify their rosy predictions of breakthrough energy in the next decade.
And not in the article but on a personal note, I'm skeptical of any argument like "of course for a mere $500 million a year we couldn't get any results. If those stingy governments had just given us $5 billion like we'd asked, we'd already have met all our goals! C'mon, it's only $5 billion a year, just hand over the check!"
Anyway, not trying to be too negative. I appreciate the review and research overview, and I'm hopeful that you're right. But this other article really put some cold water on my feelings about fusion.
I have not read the article, but I will read it and get back to you.
It is probably a good instinct to be skeptical of people asking the government for $5 billion dollars a year. The burden of proof should be on the people asking for the money. I think that fusion funding is more worthwhile than a lot of the other things that the US government spends this sort of money on.
“ I'm skeptical of any argument like "of course for a mere $500 million a year we couldn't get any results. If those stingy governments had just given us $5 billion like we'd asked, we'd already have met all our goals! ”
What business are you in generally? In mine, it’s generally senior management that says we need X. Ok, fine says the engineering staff. We need 20 people for 2 years and $20 million. Oh no, says senior management, we can’t do that. You need to do it in one year with 10 people and $10 million. Ok, sure, whatever…
A year later and we’re 30% done. OK executive VP Bob, what now? Admit failure? Or say, “mistakes were made” and “we need another year and $10 million?”
When I read the original statement I’m like, “Of course, how else could it work?“. Obviously there is a vast chasm between what can be done and what can be done with the manpower and budget we’ve been allotted.
What if you tell them you're ZERO percent done, and that with a mere $10 million a year you'll never, ever be able to solve the problem? That's what "fusion never" sounds like to me. I mean, they might be right about needing more money, some problems just require a lot of resources at once to make any progress. But it could also be a convenient excuse for failure. Basically every single project is always, always asking for more money, and someone has to tell them no.
But we aren’t 0% done. We’re 30% done.
We aren't even 2% done.
I think it's always worthwhile to be a touch skeptical of technology development projections, so I'm with you on that theme.
But I'm a little confused by your point about the budget. It looks like really going after it would have been something like $3 B a year, and instead the US has been spending something like $500 M. So let's say 15-20% of the asked for funding. I don't know about your field of work, but in my experience that level of funding is basically "maintain what you have." It seems like an upside surprise that fusion work has been making any progress, maybe primarily based on external technology improvements like superconductors. In what scenario would you expect anything other than stagnation?
I'm just a cynical asshole who assumes the worst of everyone. So I assume that any big government project is going to be led by self-interested bureaucrats who will ask for as much money as they can possibly get away with, make up some excuse for why they need that funding, and then when it inevitably gets funded at less than they asked (because the other government actors are familiar with this scheme) they point to that less-than-100%-funding as an excuse for any failure.
Given the huge advances in superconductors and supercomputers, you'd think they would have surpassed the 90s Q-levels by now.
I am now wondering if the cooling on funding for fusion research happened due to the cold fusion scandal. I can't but think that gave *all* fusion research a black eye, and all the politicians and other bodies who complained about NASA funding when that money should have been going to [social problems] would naturally vote down any proposals to fund a proven boondoggle. Fusion research was now firmly in the "snakeoil and perpetual motion machines" box.
https://en.wikipedia.org/wiki/Cold_fusion
"Many scientists tried to replicate the experiment with the few details available. Hopes faded with the large number of negative replications, the withdrawal of many reported positive replications, the discovery of flaws and sources of experimental error in the original experiment, and finally the discovery that Fleischmann and Pons had not actually detected nuclear reaction byproducts. By late 1989, most scientists considered cold fusion claims dead, and cold fusion subsequently gained a reputation as pathological science. In 1989 the United States Department of Energy (DOE) concluded that the reported results of excess heat did not present convincing evidence of a useful source of energy and decided against allocating funding specifically for cold fusion. A second DOE review in 2004, which looked at new research, reached similar conclusions and did not result in DOE funding of cold fusion."
https://en.wikipedia.org/wiki/Pathological_science
"Pathological science, as defined by Langmuir, is a psychological process in which a scientist, originally conforming to the scientific method, unconsciously veers from that method, and begins a pathological process of wishful data interpretation (see the observer-expectancy effect and cognitive bias). Some characteristics of pathological science are:
- The maximum effect that is observed is produced by a causative agent of barely detectable intensity, and the magnitude of the effect is substantially independent of the intensity of the cause.
- The effect is of a magnitude that remains close to the limit of detectability, or many measurements are necessary because of the very low statistical significance of the results.
- There are claims of great accuracy.
- Fantastic theories contrary to experience are suggested.
- Criticisms are met by ad hoc excuses.
- The ratio of supporters to critics rises and then falls gradually to oblivion."
I think "pathological science" also covers the case of Mr. Lemoine and LaMDA.
Ha, I was fresh out of graduate school when Pons and Fleischmann burst on the scene. Haven't heard those names in donkey's years. I don't *think* cold fusion gave a black eye to real fusion, on account of none of the pros took it seriously from Day 1. (Neither of the principals was even a physicist, let alone a fusioneer.) I do recall a few people who ran a few quiet calculations on weird possible scenarios and uniformly concluded ha ha no way.
I think the big mystery was how both these men, sober serious scientists with good careers, fell into this weird rabbit hole of hype and delusionment. It puzzled a lot of people, as if the Queen had been discovered slumming it in a strip club for pin money.
It's possible one effect it had on Congressthings and Senateaux was for them to be more impatient with the "$5 billion/year + 20 years, tops, and we'll have....a really awesome publishable paper for Nature" crowd. They may have thought these unimaginative plodders just need to broaden their horizons, take a page from alternative medicine[1] and astrology, try being less skeptical and investigate weird alternatives that, sure, violate Conservation of Energy or common sense -- but which might actually work out! You never know! There are more things in Heaven and Earth et cetera...
But I think really it was just the same reason the SSC never got built, and the Apollo Applications Program never happened. People got restless after a while with nothing but cheerful reports that concluded no, we didn't achieve any breakthroughs, aren't going to do your constituents a lick of good for their tax money, but by golly we understand the problems so much better now! Another check, please. So they said well here's a pittance to keep going, bceause we're not Neanderthals, we fucking love science too, but come back to us for the big money when you've got something a lot more concrete.
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[1] Yeah, Tom Harkin. Sigh.
Jassby's claims that magnetic confinement fusion (MCF) has stagnated for the last 25 years, while inertial confinement fusion (ICF) has progressed. I do not disagree: "There has been little progress towards a larger triple product since 2000." I think that this is about to change, while Jassby does not.
There is a simple reason why MCF has not progressed. In 1997, the best MCF experiment in the world was JET. In 2022, the best MCF experiment in the world is JET.
There's only so much we can do with JET's size and magnetic field strength. They could probably get up to Q = 1.5 if they really tried, but not the Q = 5 that you need for a power plant. Instead, JET has been focusing on other important goals like getting the walls right and increasing how long they maintain the plasma. As soon as we get a better experiment, we will get better results, whether it's SPARC or ITER.
It is true that computer simulations did not predict JET very well and underestimated the turbulent transport. Computational plasma physics is a lot better than it was in the 1990s, along with everything else involving computers.
Jassby makes a big distinction between beam-thermal versus thermonuclear fusion. I don't know of anyone else who cares about that distinction. His footnotes for it all point to papers he's authored by himself.
There isn't a physical difference between beam ions and plasma ions. An ion typically has to collide a few hundred times before it undergoes a fusion reaction. So by the time fusion occurs, the ions from the beam are thermalized and are indistinguishable from the ions originally in the plasma.
He also seems to use the terms to describe how the plasma is heated. When the plasma is mostly heated by the beam, then Q must be small, and when the plasma is mostly heated by fusion, then Q must be large, ... because that's the definition of Q. The causality is backward. "For a purely beam-thermal system, the maximum theoretical Q is limited to less than 2" should be "When Q is less than 2, the system must be primarily heated by the beam."
Tritium is very expensive. You don't want your reactor to have to import it.
Each fusion reaction consumes one tritium and produces one neutron. Each breeding reaction consumes one neutron and produces one tritium. It looks like, in order to sustain this, you'd need perfect efficiency, which is impossible.
Which is why we're also planning on including a neutron multiplier: beryllium.
Be + n -> 2 He + 2 n
This increases the number of neutrons, which allows the system to sustain itself with less then perfect efficiency.
Jassby does not think that SPARC is a game changer: "improving cost-effectiveness is surely a distraction for MCF research". I disagree. Cost effectiveness is important on its own. And it means that we can build more reactors faster. It won't take us 25 years to get the money together to build the next big experiment.
I agree that inertial confinement fusion has made a lot of progress recently: "Progress has been extremely rapid. They crossed Q=1 a few months ago."
The big challenge remaining for ICF is going from 1 shot per day to 1 shot per second. NIF is not trying to do this, because fusion isn't their main goal. Maybe Marvel or someone else will figure it out. I hope that they do ! But I suspect that this will be harder than getting fusion using a tokamak.
Thanks for the detailed response! I really appreciate it. I feel like it really ups the level of public discourse on the subject when we good detailed, good faith back-and-forth like this.
> That all the fusion "startups" and mini reactor projects have so far mostly failed to produce any fusion reactions at all
Except for the ones that have the best prospects, like Helion and perhaps Zap.
Hi!
Thanks for the review. I'll read the comments and respond if I can add anything of interest.
If you assume the success of the different projects is independent, your expectation of fusion by 2035 should be >98% and >99.75% by 2040 . So 80% and 90% seems off. Do you think the projects' success is that much correlated?
I don't think that you should be >99.75% confident about anything humanity will do by 2040 because X-risk by 2040 is probably above 0.25%.
Some problems for getting fusion would only affect one player, but others would affect multiple players at once - although probably not everyone. If the venture capital dries up, then that affects all the startups but not the government players. If ITER can't get disruptions under control, then that affects all the tokamaks, but not the stellarators or other designs (although SPARC would probably have figured this out before ITER). We should probably count the 11 partially independent projects in the table as about 3 fully independent projects.
I also threw in a bit of a "maybe this person is crazy" factor, even for myself. The predictions for the particular players are all inside view. The headline predictions attempt to be outside view.
Did you take all of that into account to estimate your 80% and 90% or were they more gut estimates?
The estimates for particular experiments were gut estimates. But I did take all of that into account for the headline estimates. I thought it was likely that someone would challenge me to a bet on the headline estimates and so made them as defensible as I could.
This review speaks at length about fusion but I'm not clear how exactly it is used to generate power - is it still fundamentally producing heat for steam for electricity generating turbines? Later on the article mentions another option for generating electricity but does not expand. I think the article would have been a bit stronger with a brief overview of the full plant concept including the stages beyond fusion itself.
I'm hopeful that the technology works out, will follow it.
Yes.
Most of the energy leaves the plasma with the neutron, which deposits that energy in the tritium breeding blanket. Coolant is pumped through the blanket, which takes the heat to a steam turbine.
What happens to the helium that is produced in the fusion reaction?
It stays in the plasma. Once it deposits its heat in the plasma, it has to be removed.
If fusion became a practical source of energy, would it also be a way to fix the impending helium shortage?
I hear the helium shortage isn't as bad as made out.
I haven't heard of anyone suggesting that we do this. I doubt that the volumes of helium involved would make much of a difference.
Fuel costs are going to be a small part of the total cost of the power plant, and selling the helium "ash" would be a small part of the total revenue.
I think in an older Astral Codex post someone does a break down of the helium produced using fusion. IIRC the amount of helium produced is tiny and would be incredibly difficult to collect.
I've been working on fusion for the last year under an Emergent Ventures grant, and working alongside Schmidt Futures and Adam Marblestone to identify philanthropic opportunities in the space. That doesn't by any means make me an expert, but it's enough that I'm willing to share my opinion.
I think every prediction on this list is about an order of magnitude too optimistic, with the exception of CFS and ITER. I would also clarify that while Q>5 in steady state would be a momentous achievement, it's still puts us a far ways off from fusion energy that is economically or climate relevant. For example, I am fairly optimistic that ITER will "work", but it doesn't actually provide us with a path to commercial fusion energy.
Having said that, I think fusion is absolutely worth pursuing, and that in fact, we're severely underinvesting at the margin even with my revised predictions. Concretely, for the industry as a whole, I would give us a 20% chance of having fusion energy on the grid by 2035, and a 35% chance by 2040.
I'm happy to chat more with anyone here who's working on fusion, or just anyone who's interested:
KyleSchiller@gmail.com
Thank you for coming and sharing a different perspective !
1. After Commonwealth and ITER, who do you think are the most likely candidates to get Q > 5 before 2040? Do you have more hope for other startups or for government run DEMOs?
2. You think that it is less likely for fusion energy to be on the grid by 2035 or 2040 than I do. Is that because you think that my time frame is too optimistic or because you think that Commonwealth will be unable to solve the problems?
3. I know very little about the philanthropic side to fusion funding. My impression was that most of the money is either government or venture capital. Which of the players have been pursuing philanthropy?
1. I like Zap. There are also a couple pre-launch startups I'm funding and fairly optimistic about. I've talked to people smarter than me who like ICF.
2. I would describe myself as super optimistic about CFS, and would have been happy to invest in their latest round. But all startups naturally carry risk, and I just don't feel like we have that many real shots on goal. For what it's worth, I think the distribution is kind of bimodal, in the sense that if we don't get fusion in the next few decades, we might lose the window of opportunity.
3. Not that many! Simons is one of the major players
https://www.simonsfoundation.org/2018/07/24/foundation-announces-simons-collaboration-on-hidden-symmetries-and-fusion-energy/
Malcolm Handley has done a bit, as has Schmidt Futures.
https://strong-atomics.com/
Bill Gates is invested in fusion through Breakthrough Energy, and Jeff Bezos is invested, but I'm not sure if either has done much philanthropic giving in the space.
The issue is that energy is fundamentally a market, and fusion is a highly path dependent technology such that subsidizing reactors that aren't going to be economically relevant on their own footing is not a great option.
I am personally excited about philanthropic funding for fusion "tools". Things like material testing/development and tritium systems which benefit a variety of companies and reactor approaches.
1. Zap does look interesting. Z-pinches have had a lot of work done on them, so Zap doesn't have to build everything from scratch. They haven't been a main focus of the fusion community for a while now.
If I remember correctly, a major problem was that it is unstable to kinetic instabilities, even when it is stable to fluid instabilities. Consider a particle running along the central axis of the plasma, with a velocity almost parallel to the magnetic field. This particle will not be confined and will escape out the end. Maybe we don't care: there aren't very many particles like that, so we don't lose much by losing them. But as that part of the distribution function depopulates, there is a two-stream-like instability that puts more particles in that state. So instead of just losing the few particles whose velocities were initially well aligned with the magnetic field, you get a steady leakage that ruins confinement.
I haven't read through their papers yet, so maybe a solution is described there. It's wonderful that they have a bunch of papers publicly available.
The velocity shear is a clever way to allow you to run more current through the plasma without triggering the kink instability. Velocity shear should also help suppress turbulent transport.
(Looking back through this, this really isn't written to a general audience anymore. If anyone wants me to explain anything more fully, please ask.)
2. I could see the case for it to be bimodal. If we don't figure things out in the next few decades, it would mean that the problem is much harder than we expect. I also don't think that there will be nearly as much support if this generation of experiments fails.
3. I was aware of Simons, but hadn't really categorized it as philanthropic funding for fusion. I had not heard of Strong Atomics. Thank you for the resource !
Philanthropy for fusion tools makes a lot of sense. Ideally, you'd try to remove a challenge that almost everyone will face, and make it available to everyone. Materials and tritium breeding are both good options. Diagnostics and remote maintenance would also fit in this category.
I wonder if SPARC will rent out time for other groups to test their materials, etc, with a 14 MeV neutron source.
I consider Helion the most promising fusion startup for a number of reasons, but one of them is that their plan for a commercial reactor has Q = 0.2. This is feasible because of they can recover the input energy with very high efficiency (95% in a prototype.)
You haven't convinced me that this is anything more than the usual techie over-optimism: "yeah all the other times failed, but this time for sure!"
You also don't explain *why* the US etc. gave up on funding fusion research, or why other countries didn't surge ahead with this technology and leave the US eating their dust. Instead, your best candidate is one that is funded by a grab-bag of countries who may or may not decide to pull out at any time.
My impression is that fusion didn't get funded because "too difficult, too technical, a lot of ways it can go ka-blooey, and there were easier, cheaper methods of energy production".
Even what you describe as the new way forward with private funding is a lot of "doing experiments" and not "by 2040 we will have commercial energy generation via fusion".
I'm sorry to say that from this, I'm expecting fusion to be left behind as one of the 'flying cars/moon colonies' dreams of the 70s that never happened, and that renewable energy such as wind, solar and so on will take up the slack (along with nuclear) when it comes to being the shiny new tech for energy generation.
And as Derek Jones points out, you haven't reviewed the book, you've told us (very informatively) about fusion and what your opinion of the state of play is.
To boil the argument down to one sentence: Fusion is closer because building reactors is 10 times cheaper than it was five years ago.
I don't have a good understand of how countries decide how much research money to spend on what projects, but I guess that it involves competitive posturing more than technical plausibility. The fusion community refused to take part in the Cold War, so there never was a Fusion Race.
Investments in renewable energy (particularly wind and solar) over that time period have led to exponential decreases in price. Even if fusion does work on your timeline its not clear why it would be able to compete.
US taxpayers, vice the Federal government, have generally taken a dim view of funding by tax money -- which, please bear in mind, is taken forceably from individuals, it's not a voluntary donation -- any activity that is best characterized as developing new technology from known science, or optimizing technology. We will fund a modest amount of basic research, stuff that won't pay off for decades, if ever, on the grounds that the timeline is just too long for the private sector. And of course research that leads to weapons, since we don't want private efforts in that space at all, and national prestige projects like Apollo, because waving your flag and hooting "We're Number 1! Oorah!" is a thing among primates, and if we pay too little attention to that we alas lose some important elements of social cohesion.
But for all kinds of applied R&D, or anywhere where someone can enthusiastically say "We will have a viable commercial product within the decade!" we generally think "well if this was such a good idea, why doesn't some commercial firm form around doing it? Why should The People bear the R&D costs for value that we can accurately predict will accrue to private shareholders not long from now?"
That's why the Federal government funds basic research into biochemistry, but not actual drug development -- that's left in the hands of Pfizer and Roche and so forth. That's why DARPA funded the basic research around networked computing that gave us a fledgling ARPAnet -- but then got out of the business, and so AWS and Wikipedia and Github are all private ventures.
It's generally been a pretty successful model. At the other extreme, we have the Soviet model, where *everything* was centrally researched, developed, designed and deployed, and that has not worked out well -- not technologically, not ecologically, not economically, and not on humane grounds. It's a cautionary tale.
I think that there is a principled position you could take about what things are and aren't worth government money and conclude that fusion should not be supported. I don't that any government's actual spending aligns with this. Fusion is a more worthwhile than a lot of things the government does.
I do not think that we should be anywhere close to the Soviet extreme. A lot of the recent progress in fusion has been made in the private sector.
Yeah but "the government does a lot of damn silly things with your money already" is not a very persuasive argument for trusting still more of my money to their decision-making processes.
Anyway, I was not making an argument pro or con for Federal fusion research money, I'm just observing that it should not be a surprise that Federal support for the last stage before commercialization -- which is where you're saying we are, remember -- will be meager. Things like Project Apollo or the Manhattan Engineering District are *anomalies* that happen for weird combinations of historical and social reasons, they are not the way things usually work.
The United States tends to spend about ~$20 billion/year on basic science and technology research (much more on medical/bio), so it was always a dubious proposition that fusion power would get like 20% of that, in the absence of some giant special-purpose program (and we're back to Apollo/MED are anomalies).
To your other comment about the US spending $20 B a year on R&D a year, I would argue that number is ridiculously low. The ROI on DARPA, GPS, the NIH, and so on has been huge. For any organization to get on the order of a 100X return on R&D at say 0.3% of the budget ($20 B out of $6.8 T) and to not double down is just asinine. The marginal return for spending more should still be amazing. Sure, there are political constraints on the budget process. We may not be able to always make the right spending decision. But I don't see how anyone can argue that this is the optimal amount of R&D spending for the US.
Perhaps going forward fusion is close enough to commercialization to be handled by the private sector, although I'm skeptical. Retrospectively, unfortunately we've been asleep at the wheel for the last 30 years in terms of public sector support of this research. I would say the same about fission, which I imagine would work about 10X better now if we hadn't mostly stopped developing the technology 40+ years ago.
That's just physical sciences, and I'm roughing it out based on the NSF's budget, and making some vague allowance for DOD, DOE, and NASA grants. NIH spends about 3x more, and overall there's a lot more money in medical and basic biochemical research.
Yes, many people have argued the US spends too little on basic research, but to the extent people want to spend more, these days it's more often on bio stuff. Physical sciences had a heydey from 1945-1985, courtesy of The Bomb, which impressed everyone with what physics could do, but it's been kind of on the wane ever since -- helped along by people like the unlamented former Senator Barbara Mikulski (D-MD) who would inveigh against mere "curiousity-driven" research as frivolous excess compared to whatever trillion dollar corn dole she preferred.
(1) Do other experts agree with the 80%-by-2035 prediction?
(2) Why should I care if we "get fusion"? Does the cost of energy decrease (how much?), or what other effects are significant?
1. Sort of, but only publicly, and only because they are raising grant funding or VC funding. Privately, my sense is that most experts would give a much lower number.
[EDIT: I was mistaken. Yes, I think many experts would agree that SPARC and/or ITER will likely get Q>5 by 2035.]
2.
- It's baseload, so you don't need nearly as much storage (this will be severe limitation for solar as we approach higher penetration).
- It's "clean", meaning no carbon emissions from operation (though you're still using steel and concrete to build the plants.
- It's much safer than fission plants (you can leak some tritium potentially, but there's no risk of a meltdown), meaning no 100 billion dollar cleanup efforts and in theory fewer barriers to public acceptance.
- It's effectively renewable if you're doing D-T since D comes from sea water and plants will be tritium self-sufficient.
Basically, if it works, this is the holy grail for energy. The cost won't be considerably lower than existing energy sources in the near-future, but if things work out, it will at least be competitive even without subsidies.
From your other comments, it sounds like you think that my estimates: SPARC gets Q > 5 by 2030 (70%) and ITER gets Q > 5 by 2035 (50%) are reasonable. Did I understand that correctly?
That is not too different from: Anyone gets Q > 5 by 2035 (80%).
Ah yes sorry, added an edit.
The tritium breeding consumes lithium (particularly lithium-6), which while more common than fission fuels is still a fair way from "effectively free/infinite" as I'd stipulate for "renewables".
And it could be scaled up with decreasing costs over time due to learning effects and whatnot, I assume.
(1) There is a lot more optimism than there was even 5 years ago. I don't know of any survey that has numerical predictions.
(2) Kyle Schiller's answer is good. I don't have a good estimate for energy costs.
Helion is the star in terms of 'society changing energy revolution' with an estimate of 1-6 cents per kWh based on reactor survivability. It also seems like ZAP has the engineering possibility to be a radical change. It will be extra interesting to see what their next experiments do. I listened to a General Fusion public relations presentation and Q and A the other day and they gave 5 - 6.5 cents as their current estimate. I assume Helion is the best physics bet but should be considered a worthy longshot
What I'm very curious about is how much confidence there is out there about the simulation prediction of high power tokamaks tolerating doubled or more density, and if that should straightforwardly double pressure and quadruple maximum output? I imagine then the limit on the commercial price would become divertor and inner wall survivability and be sub 10 cents per kWh with more physics confidence
I don't think that the plasma physics for Helion or General Fusion is understood enough for them to make accurate cost estimates.
Increasing the density of the plasma would be great. It is also hard to do. Higher densities tend to drive more instabilities, which make it harder to keep the heat in the plasma, increase the chances of disruptions (for tokamaks), and make compressing the fuel more difficult (for other designs). If the limit is divertor survivability, then the plasma physics problems are solved and you need a materials scientist to help you.
Footnote 5 is just a duplicate of 4.
I recall over a decade ago Mencius Moldbug pointed to ITER as his example of over-funded science:
https://www.unqualified-reservations.org/2010/01/hanson-moldbug-debate/
I don't know if he's talked about fusion at his substack, since a paying subscription is required to comment there.
Sorry about that. Footnote 5 should say:
This is an order of magnitude estimate. Fire occurs at a few hundred or a few thousand degrees Kelvin (or Celsius or Fahrenheit).
Probably my fault, I had to convert the footnotes to a format that made sense on the blog, sorry, fixed.
Did something happen to the equations as well? They seem to be missing equals signs, and the numbers that are said to be subscripts and superscripts are appearing on the same baseline.
I think there are quite a few more private fusion companies than you listed, for example https://lppfusion.com/
Yes, there are. These are the ones that I think are the most promising. The book goes through 5 more that I don't mention.
Is there a reason dense plasma focus is not a creditable approach to achieving commercial fusion? I didn't see that particular method discussed in the review.
Great article! I had no idea we made consistent progress on fusion for so long. However I'm very surprised that the author thinks that three of the current major companies working on fusion are likely to succeed (70% by 2040). That seems incredibly unlikely to me, as just in general most startups fail.
There are more fusion startups than this. I think that most of them will fail. I am only mentioning the ones that I think are the most promising.
Thanks, that makes sense. Could you comment on fuel costs associated with at-scale fusion energy production? Also, do we know the upper limit on Q?
The upper level of Q is infinity. This is 'ignition', when you don't need any external heating for the plasma.
The fuel costs should be very low because the energy density of fusion fuel is extremely high. 1 gram of deuterium and lithium releases as much energy as 1 ton of coal. The construction and maintenance costs will be more significant than the fuel costs.
It doesn't seem to be controversial that we will reach fusion eventually if we follow tokamak extrapolations (though I think your timeline is super optimistic). The question is how cheap and scalable would this generated energy be. It is very possible CFS's SPARC will go online, generate energy, but self-destroy through neutronicity.
In any case, I'd love to hear: what is your prediction for fusion energy costing under 3.2¢/kWh (or any other price) in 2035 or 2040?
I have not looked into pricing for fusion power plants in any detail, so my prediction would not be much more valuable than a layman's.
The fuel cost for fusion is negligible, so the cost is primarily construction.
I strongly suspect fusion power has already been solved, although the specific details is a confluence of both conspiracy theory and culture war. (Basically, just, suppose a government has fusion power, and imagine what they'd do to situate themselves before releasing it.)
As someone in the fusion community, I can say that we're really bad at conspiracies and culture war. Unless you count tokamak vs stellarator vs inertial confinement as a culture war.
No government is competent enough to have both developed fusion power in secret (in a way that leading plasma physicists in public isntitutions cannot) and managed to keep it a secret for years or decades.
I think it has been weeks or maybe months, not years, if I am correct. (Big if. I don't put a lot of credence in the idea, maybe like 5%, but for the kind of idea it is, this seems insanely high.)
Fusion power has technically been solved since the early fifties, but with a bit of a noise problem.
Actually I believe technically it was solved about 5 billion years ago. :)
Try 13 billion; Sol wasn't the first star.
Culture war? Keeping fusion secret to own the libs?
I sometimes wonder what would have happened if someone had tweeted:
CHINA is winning the race to fusion but WE CAN WIN with TRUMP TOKAMAK
Hey, if a conspiracy theory has to spread, that wouldn’t be the worst one lol
> Other significant milestones are Q=5, ‘burning', and Q=, ‘ignition', when the fusion sustains itself without any external heating.
Is there supposed to be a number after the second Q?
I imagine it is infinity if you don't need to put external energy.
Yes, it is.
Nice essay about fusion power but in what way is this a book review?
I'm also surprised with the amount of credibility you give to NIF, which seems to be generally accepted as a nuclear weapons maintenance program dressed up as fusion research. My impression was that no one in fusion power takes the NIF seriously as a path to actual energy generation.
They definitely are a nuclear weapons maintenance program, with some fusion research on the side. They have increased their triple product by an order of magnitude in the last two years, which is impressive. They still have the major challenge of increasing their shot frequency from 1/day to 1/second, which doesn't seem to be one of their goals.
Their work might lead to someone else making inertial confinement fusion work (like Marvel Fusion). I don't think that they will do it themselves.
I know they were lying their arses off about their Q-value a few years ago by representing "the heat that got into the very centre of the pellet" as the denominator. Have they stopped lying?
Livermore? If they tell you what they're really doing, or even thinking, they have to kill you afterward. Not sure even Sandia is as professional paranoid.
They are no longer using the definition of Q that they were a few years ago.
I'm reluctant to say that they're lying because most of the terminology was developed for magnetic confinement fusion, so it's not obvious what the best way to translate the terminology is. They did pick the translation that made them look the best.
They now report Q_alpha, which is what fraction of the total heating is done by the alpha particles produced by fusion. Q_alpha = 1 corresponds to 'burning' instead of 'breakeven'. This isn't what tokamak people usually use, but it's unambiguous to translate.
NIF has recently gotten Q_alpha > 1. The main thing limiting the progress towards inertial confinement fusion now is shot frequency, not Q.
https://www.nature.com/articles/s41586-021-04281-w
I'm sorry, but no. It doesn't matter what they call the number, what matters is that they are still considering *only the energy delivered to the fuel," and they are still saying "A net energy gain would require fusion yields greater than the laser energy, 1.9 MJ..
This is wrong. A net energy gain would require fusion yields greater than the *input energy* to the laser. To generate a laser pulse of 1.9 megajoules, they need to discharge a 422 megajoule capacitor bank. Even if they generate, say, 20 megajoules of actual fusion output, they'd still be looking at an end-to-end efficiency of under 5%: they don't suddenly start producing useful energy by increasing the shot frequency.
If by "get fusion" we take the definition in footnote 1 (somebody does an experiment that gets Q > 5), then yes, we will probably get fusion on something like the timeline the author describes. However:
1. Q = 5 is *far* from commercially viable. Q represents an energy gain in terms of the energy going into the plasma. It does not account for all the other energy needed to run the system. The most optimistic number I have seen is that Q > 20 is commercial fusion. And even that is optimistic because of point #2.
2. Neutronic fusion (basically everyone doing D-T fusion) relies on neutrons crashing into stuff and generating heat, which then boils water, which then drives a steam turbine. So one input into the electricity economics for fusion is the cost of the generating equipment, the steam turbine itself. If we look at the other modes of electricity production that also use steam turbines, and compare the cost of their steam, we will see that fusion is clearly worse than everyone else. Coal: we mine this thing from the ground and set it on fire and it gives us heat to make steam. Fission: we mine these magic rocks from the ground and hold them together and it gives us heat to make steam. Geothermal: we drill holes in the ground until we reach hot temperatures, circulate water, and it yields steam. Fusion: we build the most complex and finnicky machine ever known to man (read: very expensive) and then it produces heat which we can use to make steam. Neutronic fusion is an expensive way to make steam, so the economics are unlikely to work if it is actually competing on a level playing field with other ways of making steam.
3. The insanely complex and finnicky machine neutronic fusion uses to make heat will need to undergo maintenance, and perhaps more often than other machines, because it is constantly being bombarded with radioactive neutrons. When it needs to undergo maintenance, it will be radioactive because of all the radioactive neutrons that have bombarded it. So maintenance will be expensive.
4. The neutrons emitted by neutronic fusion can be used to breed plutonium and other fissile material, so the technology will have to be closely controlled, which is a further headwind on it ever becoming economic.
5. Fusion advocates have tried to get fusion to be perceived as "safe" because it cannot lead to a meltdown. While it can't melt down like a fission reactor, fusion can suffer from a confinement failure (i.e., a big explosion). A confinement failure is likely to strew radioactive parts everywhere in its vicinity.
D-T fusion is indeed the closest technology to scientific breakeven (Q > 1) and maybe even to something like Q > 5 like the author suggests. But that does not mean it will ever be commercially viable. I believe that the scientists working on it know that it won't ever be commercially viable, but they don't want to say so because they want to continue to get funding either from governments or private investors to achieve the breakeven milestone.
Most of my criticisms of fusion are totally standard; they were noted by Lawrence Lidsky from MIT in 1983. http://orcutt.net/weblog/wp-content/uploads/2015/08/The-Trouble-With-Fusion_MIT_Tech_Review_1983.pdf
" neutrons crashing into stuff and generating heat, which then boils water, which then drives a steam turbine"
I do like how all the cutting-edge future tech in the end comes down to "and then we use it to drive tech invented in the 18th century for pretty much the same purposes in the same way they were using it in the 18th century".
https://www.youtube.com/watch?v=oodxIiAAZ_w
I'd think you'd love to hear about Project PACER, which was a proposal to create fusion energy by detonating thermonuclear bombs in salt caverns and letting the heat boil water to drive steam turbines: https://en.wikipedia.org/wiki/Project_PACER. It was part of the broader 'Atoms for Peace' program of Project Plowshare, more specifically an extension of the Project Gnome nuclear test that sought to harness the power of underground nuclear weapons tests for peace instead of war: https://en.wikipedia.org/wiki/Project_Gnome_(nuclear_test). The Soviet counterpart was Program #7, a.k.a. Nuclear Explosions for the National Economy: https://en.wikipedia.org/wiki/Nuclear_Explosions_for_the_National_Economy.
(See also, Project Orion: https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion). If we ever need to build an interstellar colony ship in short order, or launch a last-ditch asteroid diversion mission a la the movie Armageddon, Project Orion would be our best hope with current technology.)
That's because the power generating event is happening incoherently on the atomic scale. That is, you are essentially generating heat (= accelerating particles) at Step #1, so you can't help but put it to use as a heat engine -- and so off we go to needing a working fluid that cycles conveniently between expansion and contraction at normal ambient temperatures -- hello H2O! -- and we just add on all the usual steam power plant tech after that.
There are ways to generate powr that *don't* generate heat at Step #1, e.g. using falling water or tides, which are all harvesting *coherent* motion, and these can go directly to electricity generation (or some other form of useful work) without having to pass through a heat engine.
But basically there *are* only two ways to get useful "energy" (= work). You either convert some other form of work (tides, sunlight) to the form you want (electrical potential), or you convert heat to work via a heat engine. Unfortunately, *anything* that relies on events at the atomic scale -- combustion, fission, fusion -- is going to be making heat because we have no way of making it "coherent" (= happens at specific times, and in specific directions we specifiy).
Mind you, living cells aren't subject to the same restrictions, because they can and do engineer at the atomic level. That's why we can "burn" glucose without literally burning it, using steam expansion and so forth. Enzymes can convert the potential energy in glucose + O2 into the (much more convenient) potential energy of ATP directly, without having to go through this hokey pokey of a working fluid expanding in a cylinder et cetera.
If we were able to do the same, engineer at the atomic level, then we probably wouldn't dick around with fusion power. The Earth is continually bathed in 10^17 W of high-quality work (sunlight), which is more than we could conceivably use for a long period, even given the most optimistic assumptions about growth. If we could engineer at the atomic level, build equivalents to chloroplasts that produce whatever useful substance or energy storage material we like, that would clearly be the way to go.
" If we could engineer at the atomic level, build equivalents to chloroplasts that produce whatever useful substance or energy storage material we like, that would clearly be the way to go."
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwiZhePqmrb4AhUonWoFHYs7BL0QFnoECAIQAw&url=https%3A%2F%2Fcss.umich.edu%2Fpublications%2Ffactsheets%2Fenergy%2Fphotovoltaic-energy-factsheet&usg=AOvVaw21I7U1YPkIgllCbBxcC5Iy
"PV conversion efficiency is the percentage of incident solar energy that is converted to electricity. Though most commercial panels have efficiencies from 15% to 20%, researchers have developed PV cells with efficiencies approaching 50%."
We are already better than chloroplasts. C4 plants peak at 4.3% efficiency. 28.2% if you want to count it at the intra-chlorophyll excitation level https://en.wikipedia.org/wiki/Photosynthetic_efficiency
I think the major limitation at this point is storage. ( There are quite a few energetically reasonable options for storage, from various battery technologies to pumped storage. IIRC, the problem is getting their costs down far enough. )
Well, sure, that's the point. The plant gets glucose out of a chloroplast, a nice compact easily transported and stored fuel, not electricity which it has to use right away or waste. That's also why a comparison of energy efficiencies isn't especially relevant -- the plant is not *trying* to produce high-energy electrons, that's not its figure of merit. What you want to compare is a solar-powered chemical plant that can turn CO2 and water into gasoline. When that gets to the efficiency of a plant, we'll have something to brag about.
Well, we _do_ use electricity for a lot of our energy needs. Economical storage is a problem, though one with many partial solutions (e.g. electric cars are more expensive and shorter range than gasoline cars, but they aren't ludicrously uneconomical - off by maybe 2X, not 10X). If we used hydrogen for storage (yeah, I know, volumetric energy density is crappy - consider it for stationary applications where large volume storage is ok) the round-trip electrolysis->fuel cell efficiency is around 50% - which is better than the conversion efficiency to glucose in a plant, which loses around another factor of 4 going from chlorophyll excitation to glucose.
Those numbers don't really add up by my intuition, although I can't be bothered to check it in detail alas. Your Wikipedia article asserts an efficiency of (full-spectrum) light to glucose dG of ~11%, which sounds about right. Last I looked at solar the standard light to volts efficiency was something like ~18%, and I'm a priori doubtful you can make and store H2/O2 at better than 50% total efficency. And then let us remember that H2/O2 just gives us fuel for a heat engine --- and yeah my god a serious storage and transport issue, definitely a wretched way to store energy -- so if you want to do useful work with it, you're going to get whacked by another factor of 1/3 when you run your heat engine -- the cell has no such problem with using ATP 'cause it's not using a heat engine.
Anyway, while it's a mildly interesting hypothetical, it isn't germane to my point, which is that if we could engineer light harvesting and the construction of arbitrary molecules the way life has, it would beat the hell out of *any* conceivable energy generation coupled with manufacturing technology we've got. I'm sure you've read Stephensons "The Diamond Age." Like that.
> *anything* that relies on events at the atomic scale -- combustion, fission, fusion -- is going to be making heat because we have no way of making it "coherent" (= happens at specific times, and in specific directions we specifiy).
Isn't Helion's design a counterexample to this claim?
Could you elaborate? I don't know what Helion's design is, or why it should be a counterexample.
It's a fusion power design that isn't a heat engine. They do their fusion in discrete localized shots, and the plasma expanding in the magnetic field generates the electric current.
Here's their snazzy graphic explanation page: https://www.helionenergy.com/our-technology
Oh, I guess it does still work by generating heat... They just avoid the need for a separate working fluid to harness it?
Ah I see. Pretty fancy. I think that's still a heat engine, because the basic driving force is expansion of the plasma as it gets heated by fusion. The expanding plasma isn't pressing on a turbine fan blade and thereby turning a generator, it's more or less doing the generator thing directly, but that isn't really relevant to the thermodynamics.
Pretty slick though. I hope they make it work.
Turbines are good , because you can recommission fossil fuel plants as fusion plants and use the existing turbines.
I strongly agree with points 3 and 4. Permitting, construction times and operations and maintenance costs have a huge impact on the cost of power. Compare that to a solar farm and battery setup which can be rolled out in months and doesn’t need much maintenance for twenty years.
I have not looked at the details of how to make a fusion power plant commercially viable. I'm guessing that a lot of the answers are currently unknowable. This seems to be your main point, and I doubt that I will be able to respond to it satisfactorily. SPARC is about 1/10th the cost of ITER, so progress here is definitely being made.
Here are responses to your other points.
1. In terms of the triple product, Q = infinity is only about twice as hard as Q = 5. Getting Q > 5 is most of the technical challenge.
2. There isn't a level playing field. If there were, my guess is that fission would win. But it's currently mired in a regulatory mess. I would love to see that change, but wouldn't bet on it. Coal is cheap until you count all the people it kills. Most of what I know about geothermal comes from your blog post. Maybe it is a better option, but I would like to see both available.
3. The tritium breeding blanket should block most of the neutrons from getting to most of the components. But yes, the maintenance will be radioactive.
4. This is possible, but I don't think it's a big challenge, for several reasons. (a) Over half of the world's energy is used by countries that already have nuclear weapons. I'm not as worried about e.g. China using commercial fusion reactors to make weapons if they can just get one from their stockpile. (b) Fusion reactors are much easier to inspect than fission reactors. For fission reactors, you need to keep track of how much fuel is where continually. Fusion reactors should have any uranium or plutonium there at all. Detecting if an element is present is much easier than keeping track of how much there is. (c) I don't think that anti-proliferation inspections are a significant fraction of the cost of fission plants today. The easier inspections for fusion shouldn't a significant fraction of the cost of them either.
5. No it's not. Fission reactors meltdown because they contain months worth of fuel that can all burn at once. Fusion reactors would contain minutes or hours worth of fuel. There is not enough total energy in the reactor at any time to breach the building. The worst disruptions would melt part of the interior of the reactor, which would be expensive to fix. But it would not strew radioactive parts everywhere in its vicinity.
I know lots of people who are working on fusion who believe that it will become commercially viable. It's possible that we're wrong, but that is not the consensus of the community.
"I have not looked at the details of how to make a fusion power plant commercially viable."
Having looked up the book you reviewed online, by the table of contents they cover that in chapter eight, or at least they cover designing a tokamak power plant. Not having read the book, I don't know if they cover how to make it commercially viable.
I think that is an important omission; I can understand you being excited by interesting new science, but if you're trying to sell it to us as more than 'fascinating research' by means of 'infinite cheap clean energy' , then you really have to show how we get there. You haven't addressed *why* countries didn't put funding into fusion research, and 'I dunno, maybe Cold War?' is not a good enough reason. This is that "$100 bills lying on the sidewalk" problem all over again.
The book does have a description of what you would have to have in a power plant and what you would want to optimize. But it does not give cost estimates for construction or maintenance for an optimized reaction. I don't think that good estimates are possible right now.
For example, we need to know how long various materials can survive when bombarded with 14 MeV neutrons. In order to test that, we need to have a good source of 14 MeV neutrons. Which means we need a fusion reactor. Experimental reactors are necessary in order to make precise cost estimates.
I have not claimed that fusion is 'infinite cheap clean energy'. I do claim that it is clean and that there is a lot of fuel, but I don't know how expensive an optimized plant will be. Having an entirely new source of energy is exciting, even if it isn't better than everything else in all ways immediately. For example, I could see an economy with intermittent wind & solar power, nuclear baseload power, and fusion peaking power, even if fusion does not end up being the cheapest.
This is not a $100 bills lying on the sidewalk problem. In the analogy, the up front costs are trivial. This is not true for fusion.
Why do countries decide to spend research money the way they do? These decisions are made by politicians for political reasons. Physics megaprojects might get funded because for the military (e.g. Manhattan), for competitive status (e.g. Apollo), to give the public lots of inspiring pictures (e.g. Hubble), or because famous scientists support them (e.g. particle accelerators). Controlled fusion is not immediately relevant for the military. By not taking part in the Cold War, fusion removed the possibility for competitive status seeking - and further reduced military support. I think our pictures are cool, but we're not going to able to compete with space on that. There haven't been many famous plasma physicists, compared to high energy physicists or astronomers, and I'm not sure why. Whether or not fusion is useful politically now is more relevant to government funding than whether it's useful economically in the future.
"I have not claimed that fusion is 'infinite cheap clean energy'."
Some of your partisasns are doing that for you, or extrapolating a lot further from what you have said:
"(a) A lot of people will be upset if engineers solve this problem and the world continues on in energy abundance. How can we have Mad Max or some other dystopian future if engineers solve all the problems? Mankind must suffer!
(b) With infinite energy we don’t have to live here.
(c) Scale - solar will never make getting you to orbit cheap. Fusion can. You can’t think in terms of your energy needs now, with current technology, you need to think of “your” energy needs 50 or 500 years from now."
"In the analogy, the up front costs are trivial. This is not true for fusion."
Your book review would have been better if you had included acknowledgements of this type in the body of it, rather than in replies to comments. Yes, you want to sell us on the fantastic amazing science and the possible future benefits - but you also need to anticipate and meet the possible criticisms, and acknowledge that it's not going to be as easy as "Throw money at it and we'll have the Jetsons future in fifteen to thirty years time".
"Whether or not fusion is useful politically now is more relevant to government funding than whether it's useful economically in the future."
And *that* is part of what I have been trying to get at, as to why the Fusion Future may not come around in the timescale, or with the rosy results, that your essay hopes for.
Thank you for answering this. I think that you do have a point about fusion not being military benefit or politically favoured, but I also think there has to be something more going on - why wouldn't any country want the kudos of "we were first to solve this huge problem and now have safe, clean, cheap energy"?
"Some of your partisans are doing that for you, or extrapolating a lot further from what you have said:"
That is a lot more than what I said. I stopped following that thread when it turned into a technology good vs technology bad vs technology nonexistent argument.
"Your book review would have been better if you had included acknowledgements of this type in the body of it"
I thought I had in Figure 1 and with sentences like "the fusion community has been gathering money from all around the world for decades for a single project". Maybe I was not clear enough.
"as to why the Fusion Future may not come around in the timescale"
A big part of my argument is that we no longer are dependent on government funding. Commonwealth has made fusion cheap enough that it's within the range of private venture capital. It still hasn't been done yet and it still isn't cheap enough to compete with other energy sources, but it's a lot closer than it was even 5 years ago.
"why wouldn't any country want the kudos"
Because countries don't think. Politicians think. The question is: Why wouldn't any president want one of their successors to solve this huge problem?
for 2, I expect you can get a better carnot efficiency than with other methods by heating the steam hotter.
You say that neutronic fusion has no economic future because it's just another thermal energy competing against many other thermal energy.
I would add that thermal energy cannot grow much more because of thermal pollution.
What are the prospects of aneutronic fusion (with direct energy conversion to electricity)?
This is for me the real question: If we get aneutronic fusion, it will open a future of "unlimited" energy. Ok, let's define "unlimited" as 1000x more energy than now. Note : 1000x has already happened since the beginning of industrial revolution.
There are two relevant aneutronic fusion reactions: D-He3 and p-B.
The Deuterium - Helium-3 reaction requires about 10 times larger triple product, while the proton - Boron reaction requires about 100 times larger triple product than DT fusion. I think that both of these are achievable eventually, but they will not be the first generation of fusion reactors. You also need a source of helium-3, which might require mining the surface of the moon.
The plans of helion is to do 2/3 of D-D and 1/3 of D-He3.
The D-D reaction yields with equal probability T+p and He3+n. So D+D reactions produce as much He3 as the D-He3 reactions consume.
Helion does not consume He3, so no need to mine the moon.
Actually, Helion reactor produces tritium and hence He3 if you wait a bit. Because tritium has a half live of 12.5 years and decays into He3.
Why do you say in your article that the helion reactor is 25% D-T ? Where did you get this piece of information? It seems to me an error that could be easily corrected...
They start with a plasma with pure deuterium. As it starts to fuse, it produces an equal amount of helium-3 and tritium. Both the helium-3 and tritium will then fuse with deuterium.
In order to get 2/3 D-D and 1/3 D-He3 with no tritium fusion, Helion needs to have a way to reliably extract tritium while the fusion reaction is going on. I don't know of a way for them to do that.
Either way, I think that it's best to describe this as predominantly D-D fusion, rather than as D-He3.
As I understand they start with a mix of D and He3, which leads to the desired D-D and D-He3 reactions, but since it's pulsed, secondary reactions of the D-D fusion do not happen much because the produced He3 and T are way too high energy to fuse and have no time to cool down to the right range.
What I do not know is how they plan to capture these He3 and T. Seems less harder than the fusion per se though.
<Disclaimer that I am not an expert on Helion's plans and might be wrong.>
I'm trying to back-of-the-envelope this.
There have to be twice as many D-D reactions in any shot than D-He3 reactions in order to sustain it.
Do you know what temperature they're operating at? I'm guessing about 500 keV. At which point, the cross sections for the three reactions are about equal.
Do you know what fraction of the particles fuse on each shot? To get very few D-T reactions, I think that the answer needs to be small, but that goes against the goal of getting a lot of power out.
I'm also not sure why they're trying to not have D-T reactions.
D-T is the easiest reaction to do and releases about as much energy per reaction as D-He3, and much more than D-D.
They don't have an aneutronic reaction. They'll have to shield the neutrons from the D-D reactions (and any from D-T reactions that do occur). Maybe they think that they can shield lower energy neutrons but not higher energy.
In order to separate out the T afterwards, they probably need to use both centrifugal (D vs T) and chemical (T vs He3) separation. Definitely easier than the fusion, but it's an extra efficiency cost.
The Helion reactor is pulsed. The pulses are short enough that the fusion products don't thermalize before the pulse ends (they can do this because they recover the input energy with very high efficiency). This means the T produced is energetic, putting the DT cross section well below the peak (which is at lower energy). I believe that only a very small fraction of the produced T ends up fusing. The problem becomes separating the T from the exhaust D so it's not reinjected into the reactor.
This scheme also solves the "ash removal" problem, which also faces DD reactors. Steady state DD reactors would need to be able to separate particle confinement and energy confinement; this was a selling point of Dipole Fusion (the old LDX experiment.)
If I were hunting time travelers I would look at people trying to skip straight to He3 fusion.
Just sayin'.
Can you expand on #2? I've heard people say "but steam turbine" and it always feels like they're skipping some steps in their explanation.
The neutrons from D-T are a problem, but they are significantly less than for fission, which we can handle. And viable D-T fusion means He3 fusion is around the corner.
You don't even mention the worst issue Lidsky identified: the horrible volumetric power density of DT fusion reactors. If you look at gross thermal power production per volume (looking at the whole reactor, not just the plasma) you get:
ITER 0.05 MW/m^3
ARC 0.5 MW/m^3
PWR fission reactor 20 MW/m^3 (volume = that of the pressure vessel containing the core)
DT reactors will be at least an order of magnitude larger than fission reactors of the same power output, and present far more challenging problems of engineering. How can one expect the fusion reactor to be cheaper than the fission reactor? If it's not, how will fusion power compete with the energy sources that are already driving fission out of the market?
For this and other reasons, I consider Helion the least dubious of all the fusion efforts.
BTW, any fusion book that doesn't mention Lidsky, and any review of a fusion book that doesn't mention if it mentions Lidsky, get thumbs down from me.
I am not sure tokamak DT fusion will ever do better in cost than existing fissions reactors but let me try to argue why it could happen:
1. the primary fuel, deuterium, is dirty cheap
2. the learning curve will drive fusion prices down. Because of (perceived or real) safety issues the fission reactors are getting more expensive generation after generation. At the contrary, for fusion we can imagine a low regulation environment allowing competing companies to experiment cheaper and cheaper solutions.
Fuel is already a minor part of the cost of power from a fission reactor. So, maybe at some point if uranium gets scarce this could change, but until then the low cost of deuterium (and lithium; don't forget that's the other fuel being consumed to make tritium in the blanket) can't help much.
Most of the cost of fission power is from capital cost of the power plant itself. And there, DT fusion is operating at a grave disadvantage vs. fission, due to size and complexity.
As for safety, the major problem from the point of view of a utility is risk of losing the power plant. Fusion reactors put much more complexity in the hot part where repair is very difficult, if not impossible. Making this part sufficiently reliable is likely to be very expensive. (This is another point Lidsky made.)
Yes, I agree with you. The fast neutrons are a scourge. I actually don't think DT fusion could do much better than fission, probably worse. And fission is already not competing well with alternatives.
What I really think would be transformative is aneutronic fusion with direct energy conversion. No boiling water, no fast neutrons, shipping container size generators.
As in helion energy plans. They've received half billion to reach net electricity by 2024. If they succeed this will completely change the energy landscape.
Fusion does have other significant advantages over fission in radioactive waste, proliferation risk, and meltdown risk.
It is plausible that properly regulated nuclear fission would be cheaper than fusion. I don't think that's obvious just based on the power density because volume is not the only thing determining the cost. But "properly regulated nuclear fission" is not the world we live in. Instead, we have a hostile regulatory agency. Costs to build new fission power plants range by a full order of magnitude between different countries. Fusion is trying to get regulated like particle accelerators that produce medical isotopes, which would provide a much less hostile regulatory environment.
This is a great article but this is not a book review.
MOD DECISION: Have banned this user in the context of previous warnings.
This is the only non-Scott book review I've read the whole way through. Thank you :)
The formatting has been lost in the nuclear equations, making them very hard to read (like 36Li instead of superscript 3, subscript 6, Li). Some symbols have also been lost, like arrows and what I assume was an infinity symbol. Is there any way to fix this in Substack?
Superscript 6, subscript 3. Atomic number is at the bottom, mass number at the top.
Yes, you're right, sorry. Although that kind of proves my point :)
Not a book review, and a remarkably immature writing style for a professional physicist.
To be fair regarding writing style, he's writing for a general audience and so is probably trying to make it fun and engaging, and less like a heavy research paper.
I enjoyed reading it.
The dark horse in the energy race is deep geothermal. Watch for it to make a move in turn three.
Could somebody find a book on deep geothermal and write a review of it? (Probably less math.)
Not convinced.
Stylistic point, you talk about how the triple product is the most important thing for fusion, but don't actually explain what it is. You do quite well in some areas in explaining things in a way that doesn't require much background, but in other places slip over it
The triple product is density * temperature * energy confinement time.
Perhaps I was unclear. My point is not that it's impossible to find out, I can google it same as anyone. But when you are writing an article for a non expert audience you shouldn't be relying on them doing their own research to understand what you mean. Because they mostly won't. If they do it takes them out of the flow of the article and you don't know what explanation they're going to read and whether it fits with the flow of information you are aiming for
The peanuts comparison is amusing but doesn't seem particularly revealing since the US is far from the only place finding fusion research. Would be interesting to look at global spending on fusion and how that comaores to other projects.
One of the interesting things about fusion seems to be the unusual level of international cooperation
Another fusion physicist here (just a novice, though.)
What I always was afraid of regarding ITER was an Apollo Program-style Phyrric victory. "Hooray! We've achieved the nigh-impossible! Go us! Obviously not cost-effective, though, so let's basically shelve the whole field." Anything that's cost-effective is going to have to be massively simpler and cheaper than ITER - being just a reactor rather than a super-diagnosed experiment would help, of course - and I do think that the key innovations that come to the rescue probably are indeed going to come from outside the field of plasma physics proper.
Take heavier-than-air flight, for example. Why was it first invented when it was, around the turn of the 20th century? It's not because the Wright Brothers were far beyond everybody else (their advances in stability and control notwithstanding); you'll note that there were rival claimants to the title, some of whom did pick up support from major institutions. But they were all within a few years of the Wright Brothers, anyway - why's that? The reason is that the technological landscape had simply advanced far enough at that point, to the point of engines with sufficient power-to-weight ratios becoming available.
Can you imagine trying to make do without? Achieving heavier-than-air flight for humans by pushing the field of aerodynamics to the limit to make a perfectly-optimized jumbo-jet-sized airframe that is, in the end, capable of briefly lifting a baby into the air because all the rest of its power needs to go into lifting its own weight? There's a Phyrric victory for you.
High-performing superconductors may be, I feel, the equivalent of high-performing engines here. Fusion power is (if I'm not terribly mistaken) proportional to the strength of the magnetic field to the fourth power. Just like you could make a brick fly with a good enough engine, you may well achieve the plasma-physically "impossible" just by spamming more magnetic field strength at the problem.
Which is something I'm hoping for, myself: my interest in plasma-based nuclear power is because it's the sort of power source needed for high-thrust, high-specific-impulse (and thus high-squared power!) space propulsion. Tokamaks aren't the most rockety concept out there, I'd have to admit. So I'm looking forward to what we're able to develop - a brighter, positive-sum vision of the future is something I think is worth working for.
Welcome to the field !
The comparison between high-performing superconductors and high-performing engines is interesting. Some scientific and technological advances are done by lots of people at close to the same time, while some are isolated events. I don't know of any general way to tell which something will be.
"Hooray! We've achieved the nigh-impossible! Go us! Obviously not cost-effective, though, so let's basically shelve the whole field."
This is my fear too, which is getting me called all sorts of names down-thread as a naysayer and a science denier and a hater of goodness, truth and beauty.
I don't see anything in this essay addressing that, which is why I'm pouring cold water on the beautiful dreams. I'm not saying it's *never* going to happen, just that I think that the rosy optimism of "we've cut the 30 years down to 20" may be over-stating the case.
You were also kind of rude to people, which may be contributing to the negative reactions.
That concept of 'technological Pyrrhic victory' is really interesting and one I'll remember.
Another interesting concept is "pseudoengineering", the engineering analogue of pseudoscience.
I would like to know all the supporting technologies that've enabled the recent fusion boom. I saw superconductors in the article and I've also heard new magnets.
C.f. the old theory from the SSC comment section about how all technological advancement ultimately comes from materials science
The high temperature superconductors are the (electro)magnets. They're the big game changer. ITER has a list of supporting systems if you want to see more relevant technology: https://www.iter.org/mach/supporting
The 2.5 biggest supporting techs are better superconducting magnets and better computer simulations.
The magnets are an enormous deal because scaling up a 90s-style tokamak design to where we'd expect to get Q > 5 requires some combination of a bigger reactor and stronger magnets. The scaling effects are much more favorable to stronger magnets than to a bigger reactor: ITER and SPARC are expected to have similar Q factors, with ITER being about 3.3x the linear dimensions (35x volume) of SPARC, while SPARC's magnets are about twice as strong. The magnets need to be superconducting because otherwise, even very small losses of power to resistance in the magnet conductors would be a prohibitive tax on the energy balance of the reactor: you can make a research reactor with cryogenically-cooled copper electromagnets, but not a viable commercial reactor.
Computer models have advanced in two significant respects since the 90s. One is that they're informed by a quarter century or so worth of experimental data and theoretical analysis. The other is that a modern computer is orders of magnitude more powerful than a computer of equivalent cost was in the 90s. With a good enough simulation model running on good enough hardware, you can do design studies for prototype reactors much faster with a much higher degree of confidence than you could in the 90s, allowing designs to iterate faster and requiring fewer iterations of actually having to build full-scale hardware to validate your theories.
> This reaction can be written as:
> 12D +13T 24He +01n .
> The subscript is the number of protons that each element has and the superscript is the number of protons + neutrons [4]. Both of these numbers are conserved: if you add up the total superscript on the left, it must equal the total superscript on the right.
This has been severely mangled; it appears that the superscripts are now just normal text and the subscripts have disappeared.
For 12D, the 1 should be a subscript and the 2 should be a superscript. Same for all of the other terms. There should also be an arrow between _1^3 T and _2^4 He.
The last time I thought about a chemical equation was somewhere in the early 1980s, and even I could tell where the arrow was supposed to be and get the general drift.
Thanks for this whether or not people are willing to classify it as a book review.
15 years at best to get positive outcomes on a few plants. If the best we can hope for is 5 plants with Q>5 in 2040, and they take 15 years to build, then maybe we'll have 20 by 2055. And then maybe we'll have 100 by 2065. How many plants would you need to meet current energy demands?
And then you have the other cost considerations. Sure, the fuel may be cheap, but seriously the engineering hours and other material inputs into these reactors needs a LOT of gains in efficiency before they're feasible. Even if you assume they depreciate as fast as other plants, because of all the specialised equipment their repairs and maintenance is likely to be more expensive and the capital costs will be huge too. There is more to operating costs than fuel, and this is nothing I ever see addressed in any of the pieces I read on the topic.
It's cool science, and we should pursue it. But at this point I think it's the future of energy for the 22nd century, not this one sadly.
SPARC is being built in about 5 years, which speeds up the timing considerably.
I don't have a good estimate for what the operating costs will be. I don't think that anyone else does either (although some people undoubtedly have thought about it more than me), because we have not yet built one yet.
For ARC they project that the magnet performance will start to degrade after 10 years from the neutron flux, and last for some time after that as they are capable of double the operating strength. This seems like a feasible survivability limit
Heh, peanut subsidies
Most memorable part of the book lol. It was especially touching that the authors ensured it was clear they were not insulting peanut production
Some of the probabilities seem optimistic. South Korea's DEMO having the same probability of success as ITER when it's basically conditional on ITER's success? All these speculative private companies having a 70% chance of achieving fusion, the same as ITER's, despite having no revenue?
As a total layman it seems like these might be more accurately modelling a question like "How likely is it that XYZ will achieve fusion by a certain date on the merits of their technology, given that they don't go bankrupt or catastrophically fail or get defunded by a new government or anything else unrelated to technical problems?"
If K-DEMO and ITER were perfectly correlated, then they would have to have the same probability: in every world where one succeeds, the other does as well. I do think that it is possible, but unlikely (maybe 20%) for K-DEMO to succeed if ITER fails, or for K-DEMO to fail if ITER succeeds.
It's possible that I am overestimating the chances for some of the private companies. I don't think so (but that is the inside view). If you do replace those probabilities with 50% or even 30%, it doesn't change the headline probability too much (I tried to make the headline probability from the outside view). A few of the most likely candidates, SPARC and ITER, account for most of the probability, and there are other plausible routes in case they fail.
The subscript and superscript do not appear to be working.
"The fusion reaction chain in the sun burns six protons (hydrogen nuclei) into helium-4, two protons, and two positrons over the course of five fusion reactions. What we do is simpler."
Is this why human-made fusion reactors have so much higher energy density than the Sun? I used to think that fusion of course would be possible, because it's happening constantly in the Sun. But with more research, I found that a glob of sunstuff is slightly warm and slightly glowy, and the only reason the sun is so hot and so bright is because it's so big that the surface area to volume ratio means that that slight amount of heat and light builds up to an incredible degree. The exceptional thing about the Sun as a power plant is that it will keep on burning for billions of years.
Since any fusion power plants we build will be a lot smaller than the sun, and reasonable-sized globs of sunstuff would be pretty useless for power generation, it seems like we'd have to do something fundamentally different from what the Sun does to get useful results.
As I recall, yes, the power density (per volume) of the Sun is comparable to the power density of compost. Thus the different fuels, different conditions, and so forth.
Both statements are true. Another way to look at it is that the solar fusion has to (as a net result) turn 4 protons into 2 protons, 2 neutrons, 2 positrons, and two electron neutrinos. Anything process that needs to turn protons into neutrons + positrons + electron neutrinos is an inverse beta decay, uses the weak interaction - and therefore has a small cross section - and, in human terms, goes slowly.
All of the terrestrial fusion reactions starts with the necessary neutrons already present, either in deuterium or tritium (or, for the breeding step, in lithium).
edit: Re solar fusion
https://en.wikipedia.org/wiki/Proton%E2%80%93proton_chain
"The first step in all the branches is the fusion of two protons into a deuteron. As the protons fuse, one of them undergoes beta plus decay, converting into a neutron by emitting a positron and an electron neutrino
...
This is the rate-limiting reaction and is extremely slow due to it being initiated by the weak nuclear force. "
>Anything process that needs to turn protons into neutrons + positrons + electron neutrinos is an inverse beta decay, uses the weak interaction - and therefore has a small cross section - and, in human terms, goes slowly.
Weak force can be fast if it's a decay (uniparticular). The reason PP chain's slow is because it's biparticular *and* weak (the diproton isn't bound, after all).
CNO cycle's not all that slow (the positron decay steps are half-lives of minutes); the Sun's just not hot enough to do much of it.
That's fair. The half life of a free neutron itself is, after all, is about 10 minutes, and it uses the weak interaction to decay. Is the CNO cycle potentially in reach for us? Not that we are going to run out of deuterium in the foreseeable future...
That's most of it. We also use higher temperatures than the core of the sun.
There are important differences between what happens in a fusion reactor and in the core of the sun, but it is the most similar thing to compare to.
The sun is constrained by the fact that being glowy is a slow way to emit energy. It can only make energy as fast as it loses it as sunlight, because otherwise the core would heat up and become less dense until they were in equilibrium again.
> Q is the ratio of the amount of energy you put into the fuel to the amount of energy produced by fusion.
I think this might be backwards? Should be the ratio of power produced to power input.
I put the description in the causal order instead of in the ratio order. Energy in goes first, then energy out. I think everyone understood what was meant.
But yes, what you said is the most common way of describing fractions.
I am glad to have read this, so I'm glad it was picked as a finalist... but it's an essay, not a book review, so I'm not likely to vote for it.
I really like the section on private funding. I always figured fusion was impossible because capital markets manage to throw trillions of dollars towards any idea at least as good as “sell pet products online using a sock puppet” or “lend mortgages to people who can’t afford them.” “Unlimited free energy if you overcome some tough physics and engineering problems” seems like at least as good an idea to throw money at. This article seriously updated my priors.
Very much agreed! I haven't been watching private fusion closely, and my priors were at "Historically, private fusion companies were almost entirely jokes or frauds. They make outlandish claims, use completely different designs so they can't build on the progress of Figure 3, and they can be safely ignored. " I greatly thank the reviewer for explaining why this is no longer true, and how this has changed.
Yes, it also helps that the reviewer is himself a plasma physicist and is not a member of the new private fusion companies.
It's not going to be free, whatever about unlimited. The costs of running a power plant have to be covered, and if it's private investment gets there first, you need to return profits to your shareholders. So the costs of generating the power may be much lower than any sources we currently have, but generation costs alone aren't the whole story. Salaries for the workers, maintenance of the plant, all the other accounting and tax costs, government taxes/VAT if applicable are all the extras to be slapped on before Joe Citizen gets his utility bill for domestic power usage.
Proton number is not generally conserved in fusion. For example, in the sun proton-proton fusion gives a product of one deuterium atom, which has one proton and one neutron, via beta decay. It does so happen that D-T fusion conserves proton number. Also, the graph has the wrong inflation correction. The original data is in Fiscal Year 1978 dollars, which converts into 2012 dollars at less than 4:1, so the never-fusion constant $200M in the original becomes $800M in 2012 dollars, not the $1B portrayed in the graph.
Thank you for checking me carefully.
The conserved quantities are mass and charge. As long as the weak force is not involved, proton and neutron number are conserved. We typically avoid reactions involving the weak force because they are much slower.
I do not know what the inflation conversion was used for the graph.
I'm trying to find what caused me to write that about Alcator C-Mod. I think that the experimental group was going to be disbanded, but then those cuts were reversed. They still have a presence at conferences: there is plenty of data left to analyze. I don't think that the experiment has been decommissioned, even though they haven't done any new experiments since 2016. I probably should change the footnote once I figure out what actually happened there, or just remove that sentence.
Ah mass can't be conserved, E=mc^2.
Also, Alcator C-Mod closed in 2016 and has not reopened.
Are there any efforts planned toward building stellarators that use high temperature superconducting coils? From your description, it sounds stellarators are pretty great, so it would be interesting to know if they could also take advantage of a stronger magnetic field.
Yes. Renaissance Fusion and Type One Energy are both using temperature superconductors.
I'm kind of surprised high Tc superconductors have made such a difference, if you are talking about the perovskite ceramics. Not my field, but I thought they had problems with current density, and surely you need a very high current density for compact tokamaks.
Superconductors not only have peak temperatures, but also peak current densities and magnetic fields that they can support. Broadly speaking, high-temperature superconductors actually have this whole surface defining their peak capabilities moved outward in that 3D space in general, so they can support higher currents or fields at a fixed temperature.
Exactly. The biggest benefit for fusion is the increase in their peak magnetic field, not the increase in the temperature.
If you say so. Like I said, it's not my field so I'm not au courant in high-Tc research. But as I said this came as a surprise, it's usually hard to send a high current density through a ceramic.
Yeah I haven't been following the high Tc technologies either. But it looks like these are working at ~20 K, which counts as high Tc for super conductors.
https://arstechnica.com/science/2021/09/mit-backed-fusion-startup-hits-key-milestone-big-superconducting-magnets/
I think of high Tc as superconductors that work at liquid nitrogen temps (T>77K).
20K isn't high Tc, or even new, that was achievable in the 60s. Maybe people have made breakthroughs in ordinary metallic superconductors in terms of fabrication or current density?
Edit: I took a look at their glossy web sites, and it seems ITER is using conventional metal superconductors and cooling to 4K (expensive!) while the Commonwealth people are using YBCO or something similar only made into a tape and cooled to 20K. Apparently it was manufacturing more than anything that held back making magnet wire out of the ceramics, so well done nameless engineers whoever you are.
Yeah high Tc now means a ceramic super conductor. (or something like that I'm not sure... In a few past lives ago, (>20 yrs) I did some 'high' magnetic field stuff. but it was all liquid helium,
with maybe a 'lambda' plate to pump (and cool) the magnet more .. 8 or 9 Tesla was about the in lab maximum. (high field national magnet labs did.. higher fields.) Oh I should add that a 20K super conductor is like ~5 times better than a 4K one. At the minimum all heat engines have to follow the Carnot efficiency (2nd law of thermodynamics).
The superconductors are kept at lower temperatures so they can have higher currents and magnetic fields. The material could work at 77K, but it wouldn't be as strong of an electromagnet.
They make a difference, but not enough of one. ITER has 400x worse volumetric power density than a PWR; ARC is just 40x worse. And the high field of ARC means something like 60% of the mass of the reactor is the steel supports resisting JxB forces.
What would be better would be plasma configurations with much higher beta. FRCs, in particular, have beta around 1, vs. ~0.02 for tokamaks. The FRC companies are using normal conductor magnets, not superconductors (low or high Tc).
This was a great review. I like your writing style. Did you take lessons from Julius Caesar?
You should hear how I speak to an army.
That [CLASSIFIED] is funny since it's well known (implosion). It feels more like PR to unlink from nuclear weapons research stigma.
Before I saw this comment and looked up the nuclear weapons stuff, I assumed [CLASSIFIED] was some kind of weapons-grade lasing.
This isn't my area of expertise, but depending on what you mean by weapons-grade lasing, it is either already available for purchase for a few hundred dollars, or it doesn't go through the atmosphere.
Most important outcome of this review - I finally learned why ion plasma and blood plasma are both called plasma. And it's pretty disappointing.
(other than that it's not a book review, but it is an excellent Much More Than You Wanted to Know post!)
This is a really interesting and informative article about the state of fusion energy experiments, but I'm puzzled about why it's being presented as a book review. It mentions a book, but seemingly only in passing.
Unintended consequences:
Centralized power generation has large economic incentives to eliminate the competition of decentralized power generation. Centralized power is a target that needs to be defended.
Big is bad.
@Fusion Reviewer.
Great article, thanks for spending the time reading the book and writing this review.
You mentioned that stellarators are your 'favourite.' I think that a huge advance in the field in the past couple of years has been on stellarator optimization. Here's some preliminary reading:
https://terpconnect.umd.edu/~mattland/projects/6_optimization/
https://simsopt.readthedocs.io/en/latest/
https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.128.035001
Next frontier in stellarators is optimizing for turbulent transport, which I suspect will be much trickier.
Great book indeed! See also "The Star Builders."
Professional skeptics like to say that nuclear fusion energy and AI are always 20 years in the future, but in the last few years there has been measurable and promising progress toward both.
Waiting for fusion energy, whose operational deployment will likely take, yes, 20 years (!!!), conventional nuclear energy is the only viable way to move away from fossil fuels in the short term.
So let's invest more in fusion research, but also in building more old-fashioned nuclear reactors, because that's what we have right now.
The Star Builders is also very good, but not as meaty as The Future of Fusion Energy. It has more interviews with people involved and fewer descriptions of how things work.
I agree that we should be building more nuclear reactors now. But there are a lot of people who disagree. I hope that most of the people who dislike nuclear will like fusion.
No, they won't. Unfortunately these days these things come in partisan ideological packages that good partisan sheeple are supposed to swallow whole without thinking. Since nuclear fusion is "nuclear" something, they will oppose it because they must oppose everything nuclear if they don't want to be canceled and mobbed by their friends. So let's not waste time appeasing them, and start building those nuclear reactors. First fission reactors, then hopefully fusion reactors.
Great article, shame the second sentence is so inaccurate. Most elements heavier than helium are indeed created by fusion - but not all. For example the elements lithium to boron are created by cosmic spallation. Very heavy elements (such as gold) are mostly created in neutron star mergers, which are not really fusion.
Regarding Helion, what's your source for the 25% D-T reaction?
As I understand they plan for 66% D-D + 33% D-He3. Since half of D-D reactions yields one He3, the fuel cycle only needs deuterium as input and has tritium as a (valuable) waste product.
Also D-D reaction is not aneutronic but the neutrons are slower than D-T's
There's another discussion in the comments about this.
My source was that I don't see a way from them to prevent tritium from fusing once its produced. Their claim is that (1) the tritium is very hot when its initially produced, which is true, and (2) the time for each pulse is short enough compared to the tritium's collision time that very little of it would fuse before the shot is over. I don't know if this is true, and would like to see the calculation. But they might not have published the calculation. If you know of somewhere I can read it, let me know.
I'm also not convinced that it's a good choice for them to not use DT. It's the easiest reaction there is. Separating the tritium probably requires two processes (chemical & centrifuge). They already have to deal with some neutrons, although not as high energy ones.
If I were writing this again, I'd just say that there are more D-D reactions than D-He3 reactions, rather than saying it's 25% D-T, in order to reflect my uncertainty.
Helion's schtick is extremely high efficiency recovery of plasma energy. That is: 95% (or more) of the energy that goes into making the plasma, or that is subsequently added to the plasma by fusion reactions, can be recovered as electrical energy to a capacitor bank.
This means that they plan to operate at Q much less than 1, and still achieve positive net energy production. It also means that the vast majority of D ions do not fuse before the plasma is reexpanded. And so, there just isn't time for those T ions produced by fusion to either thermalize or fuse to any great extent.
Not using DT is really the best thing about Helion. DT has engineering consequences that render making a practical power plant very very difficult. Helion's direct conversion approach has huge practical advantages in avoiding the entire thermal side of the power plant (boiling water to make steam to drive turbines.)
Helion is not able to make a power plant with Q < 1. In order to make that work, you would need the rest of the power plant to be over 100% efficient.
If everything works the way they hope, they might be able to make a power plant with Q only slightly more than 1 (maybe Q=1.5), instead of the Q>5 required for a tokamak.
It really depends on what you mean by Q.
Normally, Q is the ratio of "fusion energy produced / energy injected into the plasma". By that definition, if they can achieve 95% recovery on the injected energy, they could achieve net energy production. That's because for every 1 unit of energy injected into the plasma, they only actually irreversibly spend 0.05 units. The other .95 units can be recycled and injected again.
I have a manifold prediction market on the likelihood 2% of the grid is fusion by 2050. It’s pretty low (33%). https://manifold.markets/J/will-fusion-provide-2-of-us-electri I’ll write some criticisms of this post in the morning.
Current state of the art is q=1 with exorbitantly expensive DT fuel. Economic breakeven would require q>4 using DD fuel instead, and DD requires ~5x higher temperatures. Radiative losses are usually proportional to the fourth power of temperature, and there are other additional ways for electrons to lose energy at extreme temperatures. A design that yields Q=1 at temp T would probably be like Q=0.001 at temp 5T. So they need to get three and a half orders of magnitude better.
Interesting. Thank you for making the market !
By calling DT fuel exorbitantly expensive, I'm guessing that means that you don't think that the tritium breeding blanket will work. Tritium is very expensive, but lithium is not.
Breeding it from lithium would work, but there aren't enough spare neutrons in all the fission reactors in the world to breed enough tritium for any significant fraction of grid power to come from DT fusion.
Back of the envelope calculation:
Each fission of U-235 releases about 200MeV and 2.5 neutrons. Suppose every fission reactor in the world is perfectly efficient so that 1.5 of those neutrons are available for breeding lithium. Suppose further that every fission reactor has an isotopically pure Lithium-6 blanket that magically operates at 100% efficiency and converts every neutron into a tritium. D-T fusion releases 17.6 MeV. So for each 17.6MeV of heat from fusion you had to generate 133.3 MeV of heat from fission. This implies the fission industry must always be at least 7.5x the size of the fusion industry if the latter relies on fission neutrons to breed tritium from lithium.
I don't know what the efficiency of the lithium blanket would be. If that number were sufficiently high then the the recycling of fusion neutrons could support a very large D-T fusion industry.
You breed it using the neutrons from the fusion reaction itself. Each fusion reaction consumes one tritium and produces one neutron. Each breeding reaction consumes one neutron and produces one tritium.
Some of the neutrons will get lost or absorbed by something other than the lithium. To compensate for that, include a neutron multiplier like beryllium:
Be + n -> 2 He + 2 n
This does cost some energy, so you don't want to rely on it heavily. Most of the neutrons produced by fusion will be used to breed more tritium, with the multiplier to make up for unavoidable losses.
Can you use natural lithium? Don't need to isotopically enrich it?
Lithium-7 requires high energy neutrons because the process is endothermic. Most reactors are not fast reactors.
I meant in the fusion reactor blanket. For what it's worth, I found this:
https://link.springer.com/article/10.1007/s10894-018-0182-1
which says:
"The reaction ...cross-sections of (7Li,n) are much lower...Therefore, lithium heavily enriched (> 80%) with 6Li is a constituent of all candidate materials considered for the absorber."
It would be enriched.
Very interesting comments to this review. I think the review is good and faithfully follows the book and there is no reason to denigrate it. It's just that the book itself is simply a description of what is the state of fusing at this moment.
Some people apparently expect more from a book. It had to be a story, not just the list of facts. Other people filled to void by inventing the story (that's what our brains do with everything) but that story is boring – “scientists were slow working on fusion energy because it is complicated, but gradually got better and after 30 years or so it will work and everybody will live happy forever”. And now they are criticizing the story and are not happy with it.
Hm, that's pretty much the opposite of how I read the other comments. A lot of people criticize that the review is barely mentioning the book. A large part of it is on developments that occurred after the book was published.
Have you read the book? Is it your first-hand impression that the review faithfully follows the book?
I haven't read the book. But even if it has added something, the book still is most likely the dry description of facts. Now I am not so sure but my point is that people expect the books to be more than that, especially they want a juicy story. Doesn't need to be even relevant to the subject but that's people how think. Even learning dry facts is easier when you put them in a story.
I won't argue against having a nice story. Some books do provide that, others are rather dry.
The review definitely packs the content into a juicy and thrilling story. I am less bullish about it after reading the other comments. But still, I found the review entertaining.
As a european taxpayer (that's not true, I don't pay taxes), I will be very upset if an american company reach fusion before us.
Re Inertial confinement: in a seminar at my university, a person working at NIF candidly admitted that they are mostly working at [CLASSIFIED] and they are not going to produce a power plant
Edit: I wouldn't be this confident in private startups now that monetary policy is tightening. I am afraid that money will flee from risky technological startups towards safer options.
Scott, maybe it's time for a Guest Post Contest so people stop trojan horsing them in as book reviews.
Question not just for the author: assuming that this is correct and the likelihood of nuclear fusion being imminent is underestimated: what is currently under/over-valued by the market?
Did you mean to reply to a different coment?
It was meant as an example of something over valued by the market
I think I have misunderstood your comment, i apologize
In the fusion market, I think that the stellarator startups (Renaissance & Type One) are particularly undervalued. This is designed where we have a lot of experience: Wendelstein 7-X is a similar scale experiment as JET. And it avoids one of the major remaining uncertainties about tokamaks: disruptions.
If you think that fusion is likely to revolutionize the electricity market in the next 25 years, then electricity intensive industries are likely undervalued. Aluminum smelting comes to mind as one example, but there are plenty more.
This is a bit like reading an article confidently predicting "we will have GAI by 2035" and then seeing in the fine print that they define "have GAI" as "there is a dense language model with 10x parameters than GPT3".
In case it isn't obvious, this entry should have been disqualified for not actually being a book review. It doesn't even pretend to be one! So, as a book review it gets a full zero out of ten from me. As an evangelising puff piece, about three out of ten - the single word sentences are genuinely cringe-worthy. However, the biggest problem with it is that it entirely skirts over the question of whether there is any possibility of fusion being an economical way of generating energy. Not impressed.
For a supposed review of a book titled "The Future of Fusion Energy", I am missing a big part of, well, the future of fusion energy. Let's say that ITER is a whopping success, and they achieve fusion. Yay for science! But - how long until a reactor can be designed and built that actually generates measurable amounts of power - let's say, a few hundred MW? How expensive would it be? How big would it have to be, just in terms of the physics of transporting away the generated heat? How quickly could this ideally be rolled out?
The thing is, if we want a highly sophisticated reactor that generates power, but costs billions to build and creates a whole bunch of radioactive waste in the process, we already have those. They're called nuclear power plants. Why should I get excited about an alternative that may or may not be technically feasible, may or may not be economically feasible, and may or may not be stable and clean?
"How long until a reactor can be designed and built that actually generates measurable amounts of power?"
South Korea's K-DEMO is will be built during ITER's experiments. It should be finished in 2037 and should deliver power to the grid. China's CFETR also plans to be selling power to the grid by "the 2030s", but they don't have as detailed of a plan yet.
SPARC should be finished by 2028. The next generation, ARC, should sell power to the grid. It takes Commonwealth only about 5 years to build their designs. So they could be generating power before 2035.
"Why should I get excited about an alternative that may or may not be technically feasible, may or may not be economically feasible, and may or may not be stable and clean?"
Technically feasible is the part that I'm addressing here. I (and others) predict that it will be soon. We don't know if it will be economically feasible and we won't have good cost estimates without the experimental reactors. It will be stable and clean.
Nuclear power plants have the risk of a meltdown. I think that people worry too much about it - dam failures are at least as dangerous - but it's a problem for nuclear power. Nuclear power plants contain months of fuel at a time, so when it all burns at once, it releases a ton of energy and can't be contained. Fusion power plants would contain minutes or hours of fuel at a time. So even if everything hit the wall at once, it wouldn't be like a nuclear meltdown.
Fusion plants will produce some radioactive waste, but no high level radioactive waste. There are no spent fuel rods that have to be stored for a million years. The waste from fusion will only be radioactive for decades or centuries, which is a lot more manageable.
I concur with the assessment that this doesn't read like a book review.
I also have significant concerns with the one-sentence brush-off that these probabilities are unlikely to be correlated. They're all tackling the same problem, and their approaches are different but--except for inertial confinement versus magnetic confinement--not THAT different. I believe that the correlation between the probabilities is far higher than the reviewer is letting on... or at least the reviewer needs to show their work.
If you assume that all of the probabilities are completely uncorrelated and combine them, you will get a much higher headline probability than what I said. So high that I think X-risk would make it a bad bet. I then made a series of ad hoc adjustments, assuming things were more correlated than I think and there's more unknowns than I think to get the estimate down to 80% by 2035 and 90% by 2040.
I'm referring to the statement, "Because the players are so diverse, the failures are unlikely to all be correlated."
As a dilettante, my reaction is, "Well, everyone seems to have the same problem with fusion, to wit, getting something hot enough that it fuses without disrupting the delicate dynamic that keeps it controlled in the first place. So why shouldn't they be correlated?"
So I'm not saying you're wrong--I'm not nearly expert enough to have more than an intuitive opinion--but you have to do a LOT more to convince me of the veracity of your statement.
At lot of it comes from trying to figure specific ways things could fail, and seeing if it applies to everything on the list. I decided to not game out a bunch of unlikely (?) failure modes in the review itself.
What if there are just too many disruptions in a burning tokamak? Then the stellarators and other designs could still work.
What if the pulsed designs can never make their experiments work at a frequency of 1/second? Then the steady state designs could still work.
What if high temperature superconductors are too sensitive too neutrinos? Then the larger reactors using more traditional superconductors, or inertial confinement fusion which doesn't use superconductors at all, could still work.
What if putting together something built in pieces across the entire world is impossible for ITER to do? Then all the players with more centralized organization could still work.
What if <something happens to the market> and venture capital is no longer available for fusion? Then the government players still could work.
What if US regulators decide to wage lawfare against fusion? Then the players in France could still work.
When there's more possibilities, a lot more things have to wrong in order for everyone to fail. Everything certainly isn't completely independent, but most of the potential problems do not apply to everyone.
I saw this critique of fusion linked: https://inference-review.com/article/the-quest-for-fusion-energy
(h/t: Marginal Revolution):
There are some substantive appearing challenges. Care to respond to these?
There was some decent discussion of the article on r/fusion at https://www.reddit.com/r/fusion/comments/uzvb5s/the_quest_for_fusion_energy/
I posted:
Very interesting to read that the JET record was somewhat of a trick shot utilizing deuterium particle beams aimed at a tritium plasma. However the likelihood of ITER's projected Q being based on that configuration seems vanishingly low. The discussion of potential X-ray sources for ICF with efficiencies of "several tens of percent" is a bolt from the blue which makes me suspicious but curious
As Baking mentions Jassby's projection of several years of deuterium plasma for SPARC seems to indicate he hasn't really incorporated the revolution of high temperature superconductors into his picture of tokamak development prospects. India is building 16 heavy water reactors which will presumably be loaded with tritium about the time it is predicted to be all gone - it seems unlikely that processing facilities won't be built if a bulk demand arises. Tritium breeding may be an obstacle but the specific claim that I have seen of up to 10% of each shot lost to the walls with a burn fraction of ~5% making it impossible to replace does not appear to apply to commercial relevant conditions of hot walls that absorb about 1%. Admittedly that appears to require a 1.2 TBR but it's a far cry from suddenly proclaiming that there will be literally no tritium fueling possible
"Very interesting to read that the JET record was somewhat of a trick shot utilizing deuterium particle beams aimed at a tritium plasma."
The footnote they provide for this claim does not say that.
I'm working my way through the article now and will respond more fully later.
Jassby's claims that magnetic confinement fusion (MCF) has stagnated for the last 25 years, while inertial confinement fusion (ICF) has progressed. I do not disagree: "There has been little progress towards a larger triple product since 2000." I think that this is about to change, while Jassby does not.
There is a simple reason why MCF has not progressed. In 1997, the best MCF experiment in the world was JET. In 2022, the best MCF experiment in the world is JET.
There's only so much we can do with JET's size and magnetic field strength. They could probably get up to Q = 1.5 if they really tried, but not the Q = 5 that you need for a power plant. Instead, JET has been focusing on other important goals like getting the walls right and increasing how long they maintain the plasma. As soon as we get a better experiment, we will get better results, whether it's SPARC or ITER.
It is true that computer simulations did not predict JET very well and underestimated the turbulent transport. Computational plasma physics is a lot better than it was in the 1990s, along with everything else involving computers.
Jassby makes a big distinction between beam-thermal versus thermonuclear fusion. I don't know of anyone else who cares about that distinction. His footnotes for it all point to papers he's authored by himself.
There isn't a physical difference between beam ions and plasma ions. An ion typically has to collide a few hundred times before it undergoes a fusion reaction. So by the time fusion occurs, the ions from the beam are thermalized and are indistinguishable from the ions originally in the plasma.
He also seems to use the terms to describe how the plasma is heated. When the plasma is mostly heated by the beam, then Q must be small, and when the plasma is mostly heated by fusion, then Q must be large, ... because that's the definition of Q. The causality is backward. "For a purely beam-thermal system, the maximum theoretical Q is limited to less than 2" should be "When Q is less than 2, the system must be primarily heated by the beam."
Tritium is very expensive. You don't want your reactor to have to import it.
Each fusion reaction consumes one tritium and produces one neutron. Each breeding reaction consumes one neutron and produces one tritium. It looks like, in order to sustain this, you'd need perfect efficiency, which is impossible.
Which is why we're also planning on including a neutron multiplier: beryllium.
Be + n -> 2 He + 2 n
This increases the number of neutrons, which allows the system to sustain itself with less then perfect efficiency.
Jassby does not think that SPARC is a game changer: "improving cost-effectiveness is surely a distraction for MCF research". I disagree. Cost effectiveness is important on its own. And it means that we can build more reactors faster. It won't take us 25 years to get the money together to build the next big experiment.
I agree that inertial confinement fusion has made a lot of progress recently: "Progress has been extremely rapid. They crossed Q=1 a few months ago."
The big challenge remaining for ICF is going from 1 shot per day to 1 shot per second. NIF is not trying to do this, because fusion isn't their main goal. Maybe Marvel or someone else will figure it out. I hope that they do ! But I suspect that this will be harder than getting fusion using a tokamak.
Really great response. Thanks!
Seems like there are several types of engineering challenges.
I'm a bit confused by the discussion of funding. The claim is made that funding for fusion research has been very low in the US, but lots of expensive experiments are described. I guess international funding is higher? I wish the article went into a bit more depth about funding levels.
International funding is higher. ITER's total cost should be about €20B. Europe is responsible for 45%. The other countries involved, including the US, are responsible for 9% each.
The largest fusion experiments currently operating in the US were built in the 1980s or 1990s. Since the US rejoined ITER in 2003, the funding is almost entirely to maintain & use existing experiments or to build ITER. There have been no new expensive plasma experiments in the US in decades.
NIF gets its funding from nuclear stockpile management. It gets about $300M per year. Their main goals are not fusion.
The private companies get their funding from venture capital. Commonwealth has raised the most: about $2B so far, and they don't seem to having too much trouble getting the funds to build SPARC.
Review aside, my question is how optimized fusion stands up against optimized geothermal energy in terms of economics and practicality. MIT seems to be the center of the energy universe, so it's not surprising that the front runners in both fields are start ups coming out of there.
https://newatlas.com/energy/quaise-deep-geothermal-drilling-questions/
Quaise is one I'm really excited about, and it seems to be imminently practical. But I would love to see an article as in-depth as this discussing the issues and history of the field. Because it seems to me that, were this technology to get working, the simplicity of a deep hole that can be plugged into existing coal fire plants (and then run forever) without building-sized techno-marvels would pull ahead.
Any input?
I mean, just look at this pitch: https://www.quaise.energy/
Green, safe, equitable, universal, stable, creates jobs for an existing workforce that we otherwise want to eliminate. The list just goes on and on. It's like solar without the batteries or scrapyard panels eating up ecosystems. Like nuclear without the radiation. I'm not paid or anything I'm genuinely just kind of mind-boggled.
So am I missing something or is this actually possible?
I think it's still an open question whether it's possible. It certainly is an interesting idea, worth pursuing, but drilling 20 km down at extreme heat and pressure is a daunting challenge. At some point the earth just forces itself closed faster than you can keep it open. And you do have to go down that far to get the best benefits of geothermal, since high pressure (supercritical) water at high temperature carries far more energy and can be used more efficiently than just regular high temperature water. Drilling "halfway" doesn't get much practical result.
Their drilling tests are going to be starting relatively soon, I think some time next year for the first one. I think they estimate $50 per MWh. Very excited to see what happens
I'm also excited to see what happens! But I get skeptical when I see a precise, simple, linear number like "$50 per MWh" for such a complex operation that is nowhere close to being operational yet. You'd think it would at least have a large fixed cost plus a marginal cost but apparently that sort of math is too hard for a venture capitalist to understand.
I was wrong, they predict $10-30 per MWh based on a certain drilling cost being achieved with a full size test rig to be built in 2024. There's a new video about it on Undecided by Matt Ferrell on youtube
One comment noted a possible risk to success in the transition areas where the glass lining produced by the energy drill will be weaker
Donning my hat as Resident Nay-Sayer, I think geothermal works best where there are volcanic fissures already open. Iceland seems to be one https://nea.is/geothermal/ and Hawaii another, and the Hawaii plant shows the risks:
https://en.wikipedia.org/wiki/Puna_Geothermal_Venture
Which is basically if you've got an active volcano, you have got an active volcano, and eruptions occur.
Trying for geothermal that is not volcano-based seems prudent, but also vastly more difficult as Charlie P points out.
They want to drill very, very deep. 20km down, where the temperature is reliably high almost no matter where you are. By comparison the deepest well bored to date is about 12km.
The Icelanders have a project but they're only planning on going 5km deep:
https://nea.is/geothermal/the-iceland-deep-drilling-project/
"The Iceland Deep Drilling Project (IDDP) is a long term study of high-temperature hydrothermal systems in Iceland. The IDDP is a collaborative effort by a consortium of Icelandic power companies and the Icelandic government, formed to determine if utilizing supercritical geothermal fluids would improve the economics of power productions from geothermal fields.
Over the next several years the IDDP expects to drill and test a series of boreholes that will penetrate supercritical zones believed to be present beneath three currently exploited geothermal fields in Iceland. This will require drilling to a depth of about 5 km in order to reach hydrothermal fluids at temperatures ranging from 450°C to ~600°C.
IDDP well A feasibility study completed in 2003 indicates that relative to the output from conventional geothermal wells, which are 2.5 km deep, a ten-fold increase in power output per well could result if fluid is produced from reservoirs hotter than 450°C .
A typical 2.5 km-deep geothermal well in Iceland yields power equivalent to approximately 5 MWe. Assuming a similar volumetric inflow rate of steam, an IDDP well tapping a supercritical reservoir at temperatures above 450°C and at a pressure of 23-26 MPa may be expected to yield ~50 MWe."
That makes me wonder why the difference? There's a heck of a change from "we're deep drilling at 5km" to "we're deep drilling at 20km". Is it just that Iceland has the volcanic activity nearer the surface?
That's an interesting project, and it makes sense that supercritical water would let you extract a much higher flux of heat, although I wonder if they need to keep it supercritical for some part of its journey up, which would be tricky perhaps.
Yah Iceland is basically sitting on top of some giant freaking lava pool. Definitely not the case on the Eastern seaboard of the US, which is old, cold, continental crust. A little surprised they don't first try it out West, where there is magma quite a lot closer in various places, e.g. in Death Valley there are actual hot springs. Also Yellowstone, of course, but people would probably get cross if they brought some honking big drill rig into the park.
Not really. I'm not at all an expert, so don't trust me here more than anything else.
I think of it more as mining the heat of the crust. It's not renewable - they'll extract heat a lot faster than it diffuses up from below. So the wells will run dry. But "renewable" isn't something you should care about. What matters is if it's environmentally friendly and if there's a lot of it. Both appear to be true.
I don't know if it's technologically possible. Or rather, what depth is technologically possible and whether there's enough heat at that depth. But it would be very exciting if it works.
Thanks for the reply!
Question for the reviewer: I read a short story a long time ago (so I might be misremembering and they were trying to get fission instead of fusion) and in the story they thought that deuterium-3, an isotope of hydrogen with 2 neutrons, would be easier to work with. How true is that?
(The conceit of the story was that D-3 is hard to make on Earth, but that either Uranus or Neptune (can't remember which) had it in abundance in its atmosphere, somewhere on the order of quadrillions of dollars worth, so a private company sending out automated harvesters (it was a robot themed scifi anthology) was seen as a high risk, obscenely high reward strategy.)
It sounds like you're talking about Helium-3 instead of Deuterium-3. Deuterium-3 is actually Tritium, and is something already mentioned in the book review as something that we produce cost affordably on Earth by smashing neutrons into Lithium. Helium-3 meanwhile is more difficult to produce, and is a preferable fusion fuel to Tritium because using it produces no neutrons, which as other people are discussing would damage a Tritium fusion reactor and make it more expensive. People usually talk about getting Helium-3 from the Moon, not gas giants, which is probably why you remember the story talking about something other than Helium-3, but we will probably get the stuff from gas giants in the future because they have so much more of it than the Moon does. (More specifically, it's available in far greater concentrations, making it far easier to extract - you'd need to process something like 20 million tons of Moon rock to get a single ton of Helium-3, while gas giants would merely require processing roughly 100 000 tons of gas to get a single ton of Helium-3, a 200-fold improvement even before you consider that gas is easier to suck up with a vacuum than rock is to scrape up with a mining drill.).
As to what story you were thinking about... err, sorry, can't help you there. It sounds like it's relatively hard sci-fi though, since it's taking pains to skip over the common Lunar He-3 mistake, maybe that helps.
I would also guess that they were talking about helium-3, but I am not familiar with the story.
Excellent overview on the tech.
Rest of it: not great.
I particularly like how the profusion of 50%/70%/whatever probabilities sum up to success for sure. Clearly a techno-optimist with very little experience in the difficulties of realizing lab visions into systems that actually work commercially. For example: where is the author's personal experience in a community of estimated success actually yielding results? i.e. has the author's estimates of success ever been tested against actual outcomes?
Nor am I particularly impressed by the funding aspect. Let's take whatever was actually paid, in the author's graph, as actually representative (it doesn't seem like it which I will get into later): the cumulative spend in 2012 dollars for fusion research from the 1970s to today is easily $50 billion.
Large Hadron Collider cost $5B; Apollo program cost $25B - it seems we have long ago exceeded the "spend" the author blithely projects as necessary. ISS is $150B - but $50B cumulatively (note 2012 adjusted dollars) vs. $150B is not nothing.
Nor are government cost estimates to be trusted - the California high speed rail as well as programs like the F35 are monuments to something besides success in outcome as opposed to success in pork barrel.
Then there's the entire commercialization aspect.
It is notable that there are absolutely NO numbers for the cost of fusion energy, anywhere in the article.
This should matter, no? Just because you get more energy in than you get out, does not mean that energy is affordable. The cost of fuel isn't necessarily the driving factor - we have real world examples like nuclear power plants where the construction plus lawfare costs are so enormous as to materially impact LCOE.
So net net: I'd be happy of the author is right - but I will absolutely not hold my breath waiting for it - not the actual scientific/engineering achievement of commercial fusion energy much less the possibility of fusion energy replacing other sources.
"For example: where is the author's personal experience in a community of estimated success actually yielding results?" I'm not sure how you want me to establish credibility while being anonymous.
"Apollo program cost $25B." That is not adjusted for inflation. If you do, the price is over $200B.
"Then there's the entire commercialization aspect." It does matter. A lot of it is currently unknowable. The message of this review is that the science is almost solved. With successful experimental reactors, with the plasma close to power plant conditions, then we can get good cost estimates for commercialization. The construction and maybe maintenance costs will be dominant - the fuel cost is negligible.
Re: personal experience - if you have converted lab projects into actual working commercial prototypes, that would be at least an example of past experience without compromising anonymity.
Re: science is almost solved: I don't see this as a science issue to start with. I see this as an engineering issue.
If there aren't even experimental reactors yet present, then any estimates for success are purely guesses - at which point numerical percentages of success are completely misleading.
For example: the most common sci-fi problems associated with fusion have to do with the containment fields and the associated magnets. Maybe these are overblown or dramaticized, but it doesn't seem obvious at first pass that the pico- or millisecond fusion experiments in labs are truly testing the stability of containment over time. Instability issues are not time constrained engineering problems as the self-driving people are discovering.
@Fusion Reviewer: Why did the DOE pull funding from the MIT group that later formed Commonwealth Fusion Systems / SPARC? And, in fact, is that actually how it happened? From a google search, it looks like DOE *awarded* funding to Commonwealth Fusion Systems in 2019 https://federallabs.org/news/doe-awards-infuse-funding-to-brookhaven%E2%80%93commonwealth-fusion-energy-project . Are you sure it was that DOE pulled funding -> the group formed a startup, rather than the group formed a startup -> DOE gave them startup-funding money and pulled their academia-money? I have no idea how plausible any of this is, but I haven't thought of any other explanations for why DOE would pull funding from an MIT group but then give money to a startup of the same people doing the same thing.
(BTW I really liked this and was happy to finally stumble into a fairly short, readable, and accurate assessment of the current state of affairs! So thank you for the post.)
The DOE decided to pull funding from Alcator C-Mod (the experimental tokamak at MIT) in 2012. Congress restored its money for another few years. Alcator C-Mod shut down in 2016. Commonwealth Fusion Systems was founded in 2018 by many of the same people would had worked on Alcator C-Mod. The DOE has since given Commonwealth some funding, after they demonstrated their high temperature superconductor.
Why did the DOE decide to pull funding? So more money could be spent building ITER.
See, for example, https://thetech.com/2016/10/20/energy-researchers-look-beyond-alcator-cmod-decommission
What about General Fusion? (MTF)
I don't know a lot about their design, so I don't want to make too strong of statements.
Compressing a plasma is really hard. NIF has spent more than a decade figuring it out. That being said, General Fusion's plasma is magnetized, so it doesn't need nearly as much compression as NIF.
The liquid metal vortex is made of lithium-lead. If the lead gets into the plasma, it will radiate out too much energy.
I wouldn't be surprised if some variation of the design could work. I expect that it will need several generations of experiments to get up to reactor level. They have one experiment already. I don't know what their best triple product is, and how many orders of magnitude they have to improve it to get to breakeven.
Review-of-the-review: 7/10
I'm glad I got to read this. It's a quantitative and specific introduction to the optimistic case for fusion power, with a book recommendation for those interested in learning more. But... it's not a book review? It's not any kind of review, really; it's forthright boosterism. Which is a good thing to have! Fusion energy is super cool and we should pursue it! And this post makes concrete claims that can help us understand and measure progress-- that's great! But I can't consider myself informed about fusion prospects just from reading this.
Like, as soon as I saw Figure 1, I thought to myself: this looks like the kind of stuff academics say to get funding for their projects. And the reviewer accepts this uncritically? Grant-writing, like political campaigns and Survivor, is a game whose sophisticated players expect that everyone including themselves is stretching the truth. The review's only acknowledgement that reality might diverge from projections is the offhand reference to a 20-year gap in the exponential triple progress trend as being due to needing larger reactors. (Why were they suddenly needed? And why did that need create such a discontinuity? The reviewer never explains.) I've also seen criticisms of the economic feasibility of fusion power on a variety of grounds (tritium production, facility requirements, power capture...) which admittedly are somewhat outside the scope of the review-- but I'd love to at least see them acknowledged and the risks quantified.
I won't be voting for this finalist but I was happy and interested to read it. As always, many thanks for contributing!
"Why were they suddenly needed? And why did that need create such a discontinuity?"
We known that we've needed them since the 1990s. It has taken 20 years to build ITER. Because we didn't have the money to build it faster.
Thank you for the overview of recent progress in fusion tech, imao it's much more interesting than just learning about another random book.
I've been following fusion since the 1960s when GE had an exhibit on it at the 1964-1965 World's Fair. It does feel closer than it did back then or in the 1970s with its energy crisis. In retrospect, we can see how some of the obstacles may have been removed by means of high speed computing, high temperature superconductors, high precision deposition machining, laser technology and a host of other technologies that didn't exist back then. There are obviously obstacles still to be removed. Back in the 1970s, I knew MIT physicists who were working on the problem, and in retrospect it feels like they were trying to fuse nuclei by rubbing two sticks together.
The 1964-1965 World's Fair was within a decade of the first tokamak, and before the Culham mission to Moscow. Things certainly have changed a lot since then !
Very cool primer of the state of the field, thanks for writing it!
I can't help comparing your bullish view of the future of fusion with the bearish one expressed by Daniel Jassby (formerly of the Princeton Plasma Physics Laboratory) in this recent article:
https://inference-review.com/article/the-quest-for-fusion-energy
Personally I know nothing about plasma physics, but my understanding of Jassby's main points is:
1. Tokamaks like JET produce a mix of beam-thermal and thermonuclear fusion. Theory says that beam-thermal fusion is limited to Q<2. Thus, to achieve higher values of Q, tokamaks must transition to a design where thermonuclear fusion predominates. Is this an extra challenge that ITER must overcome, beyond being a bigger version of JET?
2. Jassby is also skeptical that the breeding reaction can produce all the necessary tritium in practice. He claims that Tokamaks would need external sources of tritium, which are difficult and expensive to obtain.
3. Based on a comparison of 2021 results from JET (tokamak) and NIF (inertial confinement), Jassby claims that inertial confinement holds more promise than magnetic confinement -- although it also faces significant engineering challenges. In particular, he argues that inertial confinement is better able to deal with issues 1 and 2 above.
4. He concludes that "the stark reality is that practical fusion-based electric power remains a distant prospect. It is likely unachievable anytime in the next half a century."
I cannot evaluate Jassby's claims, and don't know if his preference for inertial confinement is due to some personal bias. Thoughts?
I remain persuaded by Jassby and unpersuaded by this reviewer. Jassby has also written another good article that focuses more with the logistics and engineering challenges of converting fusion energy into electricity on a commercial level, which this review barely addresses.
https://thebulletin.org/2017/04/fusion-reactors-not-what-theyre-cracked-up-to-be/amp/
Jassby's claims that magnetic confinement fusion (MCF) has stagnated for the last 25 years, while inertial confinement fusion (ICF) has progressed. I do not disagree: "There has been little progress towards a larger triple product since 2000." I think that this is about to change, while Jassby does not.
There is a simple reason why MCF has not progressed. In 1997, the best MCF experiment in the world was JET. In 2022, the best MCF experiment in the world is JET.
There's only so much we can do with JET's size and magnetic field strength. They could probably get up to Q = 1.5 if they really tried, but not the Q = 5 that you need for a power plant. Instead, JET has been focusing on other important goals like getting the walls right and increasing how long they maintain the plasma. As soon as we get a better experiment, we will get better results, whether it's SPARC or ITER.
It is true that computer simulations did not predict JET very well and underestimated the turbulent transport. Computational plasma physics is a lot better than it was in the 1990s, along with everything else involving computers.
Jassby makes a big distinction between beam-thermal versus thermonuclear fusion. I don't know of anyone else who cares about that distinction. His footnotes for it all point to papers he's authored by himself.
There isn't a physical difference between beam ions and plasma ions. An ion typically has to collide a few hundred times before it undergoes a fusion reaction. So by the time fusion occurs, the ions from the beam are thermalized and are indistinguishable from the ions originally in the plasma.
He also seems to use the terms to describe how the plasma is heated. When the plasma is mostly heated by the beam, then Q must be small, and when the plasma is mostly heated by fusion, then Q must be large, ... because that's the definition of Q. The causality is backward. "For a purely beam-thermal system, the maximum theoretical Q is limited to less than 2" should be "When Q is less than 2, the system must be primarily heated by the beam."
Tritium is very expensive. You don't want your reactor to have to import it.
Each fusion reaction consumes one tritium and produces one neutron. Each breeding reaction consumes one neutron and produces one tritium. It looks like, in order to sustain this, you'd need perfect efficiency, which is impossible.
Which is why we're also planning on including a neutron multiplier: beryllium.
Be + n -> 2 He + 2 n
This increases the number of neutrons, which allows the system to sustain itself with less then perfect efficiency.
Jassby does not think that SPARC is a game changer: "improving cost-effectiveness is surely a distraction for MCF research". I disagree. Cost effectiveness is important on its own. And it means that we can build more reactors faster. It won't take us 25 years to get the money together to build the next big experiment.
I agree that inertial confinement fusion has made a lot of progress recently: "Progress has been extremely rapid. They crossed Q=1 a few months ago."
The big challenge remaining for ICF is going from 1 shot per day to 1 shot per second. NIF is not trying to do this, because fusion isn't their main goal. Maybe Marvel or someone else will figure it out. I hope that they do ! But I suspect that this will be harder than getting fusion using a tokamak.
I liked this, and I don't care whether it counts as a book review. I'm happy to read the broader category "essays with a specific book as the occasion". I'm not as interested in this specific book as I am in fusion power, the thing itself; so why constrain the essay to merely summarizing and evaluating the book?
I'm afraid I'm not familiar enough with fusion to understand the benefits of getting fusion
The alternative nuclear source is fission. Of which there is a limited supply, but also it is what causes geothermal heating, so there is still plenty. (And if you are OK with breeder reactors, well I think there is enough known uranium to last for a (~) hundred years or more. (Long term I'm going with more 'cause I'm betting we can find more uranium... or other stuff. (my son is in love with thorium... and salt.)
A book review on why fission is so expensive might be useful. (can I ask Zvi to do it?)
Can I still vote on this review if I'm pretty sure I know how you are? Give your pretty orange cat a lot of pats for me.
Like many commenters, I do think you underestimate the difficulty of going from engineering breakeven to economic viability: not so much the engineering problem, but the haphazard funding, the bad PR of anything nuclear, the regulatory mess, the lack of political interest in anything that takes >5 years, etc. Hopefully China will succeed, and the west will freak out and try to catch up.
IMO the crucial takeaway from the post is that plot: we haven't (so far) run into serious problems making fusion work, and we don't even expect to run into more than average, we just haven't had funding to try at all. I didn't know that!
I do not have an orange cat, but if I did, I'd give her a lot of pats from you.
OK let's say it all works out as you say and we get ready to build fusion power plants. What are the costs of those plants going to be and won't they suffer from the same regulatory laws for safety and such that keep fission power from being economical? Sensible regulations for fission (and fusion) plants seem like the most important step... Well and build Yucca mountain for waste storage.
They should not suffer from the same regulatory laws.
Nuclear fission reactors can meltdown because they have months worth of fuel in them at a time. There is a lot of energy that could be released at once. Fusion reactors will only have a few minutes or hours of fuel in them at a time, so there is no risk of meltdown. If a burning plasma suddenly stopped being confined (called a disruption), it could melt some expensive equipment, but it would not get out of the building. Since there is no chance of meltdown, there doesn't have to be as intensive regulatory oversight.
The long term radioactive waste that Yucca Mountain was designed for is spent fuel rods. Fusion does not involve any uranium fuel rods. No high level radioactive waste will be produced. There is some radioactive waste from a fusion plant. But this is much lower level and only has to be stored for tens or hundreds of years. It would probably be stored on site, not in geologically stable locations.
We try to keep the public (and regulatory agencies) from associating fusion too closely with current nuclear power. I would love to see a lot more nuclear power plants get built, but since the regulations there are not sensible, we want to stay distinct.
Great writing and interesting topic
So disappointing that we have not made fusion a funding priority. It would change everything about the CO2 and climate change issues. The funding graph was an eye-opener.
A common criticism of the smaller experiment approach is that the heat flux through the walls of the machine would be too significant to prevent damage, and if your machine is too small it will just "melt".
Particularly, ITER was designed to support a heat flux on the order of 10 MW/m^2, whereas SPARC and others would be moving something on the order of 100MW/m^2 from the plasma through the walls of the reactor. A professor of fusion materials I spoke with told me that this makes small reactors impossible. Could I get some perspective or suggested reading materials as to why this might be wrong?
I know that the superX diverter can reduce this heat flux significantly, but as far as I know SPARC has not specified their diverter configuration.
I don't know what exactly SPARC is planning on using, but I know of several strategies that people have proposed to help with divertor survivability.
(1) Better materials. The material needs to both deal with the heat flux and it needs to not mess up the plasma. Heavy elements, in particular, get into the plasma and radiate out the energy too quickly. There are also proposals to coat the divertor and first wall with liquid lithium to both protect the material from the plasma and to protect the plasma from the material.
(2) The heat coming to the divertor is typically concentrated on a small area. If you can spread that heat out, it makes it easier for the material to survive. The superX divertor is one way to do this.
(3) Put a thin layer of gas between the plasma and the divertor. The gas radiates the energy out in all directions, instead of concentrating it on the divertor.
(4) Active cooling. Rapidly pump some fluid through the divertor so it carries the heat away quickly. This keeps most of the divertor cool, but you will get damage on the surface.
A power plant will probably involve some combination of these things.
I don't know of good references to get started with. Perhaps @Jason Parisi does? A few minutes on Google Scholar suggests:
https://www.osti.gov/servlets/purl/1568009
https://www.cambridge.org/core/journals/journal-of-plasma-physics/article/divertor-heat-flux-challenge-and-mitigation-in-sparc/A25A8CFADBBA33AD9AAC18F24E40A18E
but these might not be easy to read. See also: https://www.iter.org/mach/Divertor
I've done some research collaboration with SPARC team on exactly this topic. The primary reference scenario use fast strike point sweeping to spread the heat load. With sparc pulse lengths and thermal mass this *could* work, but will be pushing temperature limits of the materials and require longer time intervals between shots to allow machine to cool. They are also building capability for an X-Point Target diverter, which places an x-point at the end of the strike leg inside a semi-enclosed chamber. You get a benefit from increased wetting and surface area exposure, but in the ideal situation this would allow you to pump gas into the diverter and achieve full, stable detachment with minimal effect on the core. The goal is to test the XPT concept and see if it will work for the next bigger reactor that succeeds sparc.
I understand why everyone's complaining about this not being a book review, but to me the value of the ACX book reviews are not in their analyses of writing styles or authorship, but in the way they give me insight into topics and fields I wouldn't have looked into myself. Criticising the book's treatment is part of that, but I thought this review achieved that when it covered the research in the years since the book had been published. I enjoyed it!
i agree that scaling may solve some of the ratio issues, but am more intrigued by point elon brought up in his video about allegedly difficult to solve maintenance issues. Can tokamaks run continuously for years on end or is maintenance a pain? power plants that are in maintenance more than a very low single digit percentage of time are going to be difficult to manage.
Maintenance schedules are still mostly unknown. We need to have an experiment to get accurate estimates of the maintenance schedules.
We also don't know how fusion would fit into a broader electricity scheme. Would it function as baseload power or as peaker plants? Or maybe it would be something in between, filling in the gaps left by intermittent solar and wind? Baseload power plants need very low maintenance time. But peaker plants or anti-intermittent plants might not?
Do you know where I can find the original figure 12? Really want a framed photo of that it looks so cool!!
Here is the largest version of the picture I can find: https://pbs.twimg.com/media/FUStcLbX0AAeFlm.jpg
You can also search for "Large Helical Device" to find similar pictures, but they usually don't have someone inside.
Thanks! Do you know where I could find similar without a worker inside but super high res, like do you know of any photographers that I could buy a high dpi printable version from? Want to get a big print for my wall :)
Maybe this is what you're looking for?
https://fineartamerica.com/featured/large-helical-device-national-institute-for-fusion-science-japanscience-photo-library.html
Yes!!! Thank you! I really enjoyed the review by the way, you're a good writer and fusion is super interesting
true true. i guess i have no idea how fast a tokamak can be turned on/off (or any clue about anything else on this topic really). My impression was that it must take a while to heat stuff up to these extreme temps but maybe not.
It takes about 1 second to turn on. A lot of the heating comes from turning on the magnetic field that quickly. To turn it off, flood the tokamak with cold gas.
Keep in mind, the amount of "stuff" that needs to be heated up, the total mass of the plasma resident in a toka/sphero/whatevamak, is a few tens of micrograms. Maybe hundreds of micrograms for the very largest. Apply a room full of high-power electronics to a hundred micrograms of stuff, it heats up in a hurry.
The limit for the actual fusion parts is set by the inductance of the ginormous magnets; those don't come to full strength instantly. As the OP says, on the order of a second. There's probably overhead issues like turning on the cooling pumps and verifying adequate flow that will take longer. And to get useful electricity out, you still have to deal with the lag times associated with large heat exchangers and turbogenerators. But, probably faster than any other steam plant, and maybe competitive with gas turbines.
If you want to turn it *off*, that can be almost arbitrarily fast, a few milliseconds if you need it. Again, modulo the fact that you'll have a turbogenerator needing to spin down and you'll break it if you try to do that part in milliseconds.
nice. thanks. amazingly detailed answers!
Eh. Great to see that at least the human race is at least kinda trying at the moment. But still, not a word on how we are actually supposed to extract reliable and safe energy from such a plasma, without the benefit of half a million kilometers of colder matter to shield us from its onslaught. Am I just supposed to fit some radiator tubes inbetween those super magnets? And I can somehow strike a balance between that fluid not becoming super radio active, and my reactor lining vaporizing / transmuting away, and contaminating my plasma?
I genuinely do not know if these are all trivial problems that have been solved 50 years ago; or if we are still so busy actually building plasmas, that we unironically have no idea how to get anything resembling economic utility out of them, once they are humming along. I fear the latter. I mean its easy to talk about breeder blankets and what not; but its another one to actually build one, and run a viable busines using one.
The tritium breeding blanket is what extracts the energy: https://www.iter.org/mach/TritiumBreeding
There are multiple proposed designs. I'll describe one of them here, called the "Pebble Bed".
Most of the energy comes out of the plasma as high energy neutrons. We want these neutrons to be absorbed by lithium in order to capture the neutrons and to make tritium. The neutrons' energy will be deposited in the lithium.
The solid surface closest to the plasma is called the first wall. It's job is mostly to survive and to keep high Z atoms from getting into the plasma.
Behind the first wall, there will be a layer a few feet thick filled with pebbles. These pebbles will be made of a neutron moderator, to slow down the neutrons, beryllium, which increases the number of neutrons so the blanket doesn't need to be perfectly efficient, and lithium, which absorbs the neutrons. Almost all of the neutrons should be absorbed by this layer so they don't damage anything behind it.
To keep the pebbles from getting too hot, a fluid flows through the pebble bed and to a heat exchanger. Helium gas has been proposed because it does not absorb neutrons and so does not become radioactive.
From the heat exchanger onwards, it's a standard steam turbine used to generate electricity.
A few of the pebbles can be removed at a time and replaced by others, so we can extract the tritium to use as fuel.
This is just one design. ITER will be testing multiple Test Blanket Modules with different designs to see which is best at absorbing neutrons, producing tritium, and transporting the heat.
> 12D +13T 24He +01n .
Seems like the latex got mangled up beyond recognition.
It probably was alike to
_1^2\mathrm{D} +_1^3\mathrm{T} \rightarrow _2^4\mathrm{He} +_0^1\mathrm{n}
https://quicklatex.com/cache3/7f/ql_977960472b50d72ffe1ba3507ad2ab7f_l3.png
Written like it is, it is strictly less helpful than without any numbers whatsoever.
D+T ---> He-4 + n
would be my preferred rendition in a single ascii line.
The reviews were submitted as a Google Doc, so I used their equation editor. If I knew how mangled the equations would become, I would have written them like that.
How this is a finalist for a book review contest when it barely mentions the book, let alone actually review it, is kind of a mystery to me.
Do you have a model for thinking about the commercialization of these achievements? E.g. how much will the first generation of power plants cost to build? Will they be able to charge below current natural gas prices? Solar?
So what you're trying to say is that fusion is 20 years away...
Hah, pull the other one!
Reaching net energy gain isn't the end there will still be a long way to go after that, like sorting out maintenance issues, and trying to bring costs down. I peg it as about 60 years away still and likely only useful beyond the inner planets.
What I wonder from this post is why not the oil countries are not investing hard in fusion. They will be the ones most impacted by it.
Any comments on First Light Fusion's "Projectile Based Inertial Confinement" ?
https://firstlightfusion.com
I don't know very much about them, so don't trust my comments too much.
Talking about the pistol shrimp makes for a cool story.
I like that they have their triple product easily accessible on their website. They appear to have high enough density and confinement time, but 2 orders of magnitude too low temperature. This is unusual. Most techniques find it easier to get high plasma temperatures than high density & confinement times.
The biggest challenge faced by inertial confinement fusion at NIF has been in dealing with the Rayleigh-Taylor instability during collapse. To reach the best conditions, you need the pellet to collapse as spherically as possible. If the collapse isn't spherical, then the core will start to break up before it reaches the necessary temperatures and densities. NIF has put a lot of work into making their pellets more spherical and getting the light to shine in from all directions uniformly.
Unlike lasers which shine in from all directions and especially the X-rays from the hohlraum, collisions come in from one direction. They seem to have something that makes the shockwave bend into an arc. But this doesn't seem to me like something that can be made spherical to high enough precision. If you look at the simulations (2nd video on Targets page), it looks as though a lot of the energy in the shockwave doesn't make it to the target and that the shockwave isn't spherical when it hits the target.
Since this book review makes some explicit forecasts and this community is in general interested in forecasting: there are a bunch of questions on Metaculus pertaining to fusion. One of them pertains to "fusion ignition" (https://www.metaculus.com/questions/3727/when-will-a-fusion-reactor-reach-ignition/) . Unfortunately, there appears to be no agreement as to what fusion ignition means exactly (cf. my comment in the discussion there). Hence IMO the resolution criteria of the question are not ideal. I have tried my best to bring up some of the issues but I am a total lay person in this area.
It would be great if someone with actual expertise could weigh in there and also on the Wikipedia article (https://en.wikipedia.org/wiki/Fusion_ignition) on fusion ignition so that we can get better forecasts and knowledge dissemination on this topic.
The Metaculus question is poorly written. It gives two different definitions of 'ignition':
"If Q increases past this point, increasing self-heating eventually removes the need for external heating. At this point the reaction becomes self-sustaining, a condition called ignition. Ignition corresponds to infinite Q, and is generally regarded as highly desirable for practical reactor designs."
"This question will resolve on the date when a nuclear fusion reactor has sustained a reaction which produces more energy and heat than the external energy delivered to the system"
In the first definition, external heating is unnecessary and can be turned off. So external heat = 0 and Q = infinity. In the second definition, external heating is less than energy produced. So Q = 1. The first one is 'ignition', as defined by the magnetic confinement community. The second one is 'breakeven'. These are unlikely to occur at the same time.
The source of the problem is that inertial confinement fusion and magnetic confinement fusion use 'ignition' differently. The magnetic confinement community first started using the term for fusion. The plasma is assumed to be in steady state and is able to sustain itself with no external heating. Inertial confinement is never in steady state, so this definition doesn't make sense. Instead, their definition is that the amount of energy currently being produced by fusion in the plasma is greater than the amount of energy which is currently leaving the plasma. This means that the temperature of the plasma is increasing as the result of fusion reactions. This is not steady state, and the fusion will quickly burn through the fuel pellet.
To make this more clear, let's make a comparison to steam engines vs internal combustion engines. Steam engines have a fire going in steady state. You need to start the fire by adding heat. It only makes sense to say that a steam engine has reached ignition once it doesn't require any more external heat. It is then self-sustaining. Internal combustion engines have a fire only in small pulses. Each pulse requires external heat from the spark plugs. It is never self-sustaining. Instead, what happens is that combustion rapidly increases the temperature of the gas and burns through all of the fuel.
I don't think that ignition is the right goal for this question. Ignition probably isn't desirable for a magnetically confined fusion power plant. Even if we could reach ignition, we would probably run the plant at Q~30 because it gives us more control over the plasma.
It's better to avoid the term 'ignition' if you want to compare multiple very different approaches to fusion. Instead, define what you're talking about precisely in terms of Q. I chose Q>5 and steady state or 1 shot/sec as my criterion.
(Feel free to use this on Metaculus or Wikipedia.)
Thanks, that's very helpful!
"Fusion funding is literally peanuts: In 2016, the US spent twice as much on peanut subsidies as on fusion research."
I laughed at this one. Very fresh way of using "literally".
What do you think of Eric Lerner / Lawrenceville Plasma Physics and their "Focus Fusion" design?
No mention of Deepmind's recent contribution to plasma contouring! Also its not England, its UK. An American author I would guess.
Wonder why no mention of the Lawrence Livermore MFTF?
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