Plenty of skepticism in these comments. I've been following CFS for a while and can present a point of view for why this time might be different.
Fusion energy was actually making rapid progress in the latter half of the twentieth century, going from almost no power output in the fifties and sixties to a power output equal to 67% of input power with the JET reactor in 1997. By the eighties there was plenty of experimental evidence to describe the relationships between tokamak parameters and power output. Particularly that the gain is proportional to the radius to the power of 1.3 and the magnetic field cubed. The main caveat to this relationship was that we only had magnets that would go up to 5.5 Tesla, which implied we needed a tokamak radius of 6 meters or so in order to produce net energy.
Well that 6 meter tokamak was designed in the eighties and is currently under construction. ITER, being so large, costs tens of billions of dollars and requires international collaboration; the size of the project has led to huge budget overruns and long delays. Recently however, there have been significant advances in high-temperature super conductors that can produce magnetic fields large enough that we (theoretically) only need a tokamak with a major radius of about 1.5 meters to produce net gain. This is where SPARC (the tokamak being built by the company in the article) comes in. The general idea is that since we have stronger magnets now, we can make a smaller, and therefore cheaper tokamak quickly.
Small tokamaks do have downsides, namely that the heat flux through the walls of the device is so large that it will damage the tokamak. There have been breakthroughs with various divertor designs that can mitigate this, but to the best of my knowledge I'm not sure that CFS has specified their divertor configuration.
This was just a short summary of the presentation by Dennis Whyte given here [0]. I do not work in the fusion community.
You are right, people who flippantly dismiss fusion just don't understand it.
-Fusion has made consistent improvement, roughly in line with expectations for the level of investment (20 years away predictions were considering if we invested massively, which we did not).
- Fusion is in theory something that could give us true energy abundance. Want to just desalinate water like crazy? Want to extract gigatons of carbon? Working fusion enables these to happen woth existing technologies.
I like to think of solar, batteries, fission, and wind as compelling ways to go mostly carbon free and lower energy costs about 2x over the next 20 years or so.
Fusion is what reduces energy cost potentially another 10x, which really changes the game for lots of things. Exciting stuff. Kudos to this team.
I've always wondered: why exactly is ITER so expensive, and slow? Is the engineering required at such a standard that it should takes decades of planning and construction and tens of billions of dollars? The timeline is so dilated (started in 1988, first plasma planned for 2025!) it feels like the kind of project that's expected to be cancelled from the start.
It just doesn't strike me as obvious that reducing the major radius by a few meters would have such a huge impact on cost/timelines.
>The general idea is that since we have stronger magnets now, we can make a smaller, and therefore cheaper tokamak quickly.
It's not that simple. The big problem with magnetic confinement fusion is that you need to control turbulence in the plasma so that you can contain the reactions for a reasonable amount of time to extract useful energy. However, turbulence increases with stronger magnetic field gradients, which is exactly what you get when making a smaller reactor chamber with stronger magnets. This wouldn't be the first project claiming to be able to build a small reactor, only to discover that it's virtually impossible without a major theoretical breakthrough. This is usually left out in the venture capital advertisements for these fusion startups. There's a reason why so much money and effort is spent on ITER - it is the only more or less guaranteed path to fusion with the tech and knowledge we have today.
Not an expert, but... "Net gain" seems to be the "give us enough $Billions and years and we'll find it" holy grail of fusion power. Vs. a $4 Casio calculator I can buy on Amazon today includes a zero-maintenance solar cell that is good for "net gain, plus useful work". Large-scale solar and wind power are already real-world at commercial scale, with costs per MW-h that pretty much beat every alternative. ( https://en.wikipedia.org/wiki/Cost_of_electricity_by_source ) Old-type nuclear (fission) energy has a horrible "what was promised, vs. what was delivered" record.
Maybe your equations and power laws are right, and a "big enough" tokamak would be a competitive source of power. But then there are the details, like "big enough will cost $25 Trillion". Followed by delays, cost overruns, etc.
I'm thinking that a rational, non-expert taxpayer would say, "This fusion thing is a hundred times worse than NASA's Senate Launch System. Stop wasting my money on it NOW, and let gullible investors waste theirs instead."
There are still fundamental problems with fusion reactors that are unlikely to make them economically viable, or even carbon neutral.
Most notably, the extreme temperatures, hydrogen pumping, and high-energy neutron bombardment mean that, even with liquid metal blankets, the reactors will very quickly become brittle, probably not lasting more than a year or two. Since neutron bombardment also turns any material radioactive, not only do you need to tear down your fusion plant (or at least the expensive reactor part of it) every few years, but you have to do it with radiation-resistant robots, as human workers can't get close to the reactor after it's been operating for a while.
This is the best synopsis I’ve ever seen about it, but the skepticism comes from the lack of results
A whole generation heard about it in school decades ago. Multiple generations by now, even. Its right up there with battery/energy-storage technologies. Headline after headline, enrapturing a newer and newer idealist set of people to quickly become disillusioned. People just get tired of it.
But I’m glad to understand whats going on behind the scenes now. I’ll pay attention. Looks like a real sleeper.
This is exciting. Magnetic field strength is a key component for enabling magnetic confinement fusion. This is because energy gain and power density scales to the 3rd and 4th power with magnetic field strength but only ~linearly with reactor size. See following equations for more details: https://youtu.be/xJ2h3vbOag4?t=306
So, why is this particular announcement exciting? There are 3 factors:
1. This is a high temperature superconductor. I can't find any references, but as far as I remember the substrate they are using needs to be cooled to (WRONG, it was cooled to 20degK, see reply by MauranKilom) 60-70 degK to achieve super conductivity. Compare to magnets used in ITER which need to be cooled to 4degK. This is the difference between using relatively cheap liquid nitrogen vs liquid helium.
2. Field strength of 20 Tesla is significantly higher than 13 Tesla used in ITER. Given that magnetic confinement fusion scales significantly better with field strength vs reactor size, this will enable much smaller reactor to be power positive. See following links for more details on ITERs magnets: https://www.newscientist.com/article/2280763-worlds-most-pow...https://www.iter.org/newsline/-/2700
3. Finally, the magnet was assembled from 16 identical subassemblies, each of which used mass manufactured magnetic tape. This is significantly cheaper and more scalable than custom magnet design/manufacturing used by ITER.
The kicker is how 3 of the factors above interact with the cost of the project. Stronger magnets allow smaller viable reactors. High temperature superconductors + smaller reactors allow for a much simpler and smaller cooling system. Smaller reactors + scalable magnet design further drives down the cost. Finally, cost of state of art mega projects scales somewhere between 3rd and 4th power with the size of the device. Combining all of the above factors, SPARC should be here significantly sooner than ITER and cost a tiny fraction (I would guesstimate that fraction to be between 1/100 and 1/10,000).
edit: typos + looked at the cost of ITER and refined my cost fraction guesstimate + corrected some stuff based on the reply by MauranKilom.
> This is because energy gain and power density scale exponentially with magnetic field strength but only linearly with reactor size
Nit: It scales polynomially, not exponentially. Specifically (according to those formulas) energy gain scales with the cube of field strength and power density with the fourth power. Still massive scaling indeed, but exponentially would be something else.
> as far as I remember the substrate they are using needs to be cooled to 60-70 degK to achieve super conductivity
The video in the article shows 20 K. Could of course be that higher temperature is feasible and they just played it safe (or the video is wrong).
ITER plans first plasma for 2025 - do you think it is a coincidence that SPARC is planned for 2025 as well in that release? I think both projects will hit delays, but ITER is much further in construction, so I wouldn't bet on SPARC to win that particular race.
But they don't need to, do they? If their claim is sound, they could as well just optimize the magnets and wait for ITER to complete to offer an ITERation (pun very much intended) on the design. The fact that they focus on this weird race against an international research project makes me wonder if SPARC is mostly a vehicle to attract investors.
I'm curious if they can push the magnetic field even higher in the near future. For smaller magnets in NMR spectrometers 20 Tesla has been commercially available for 20 years. Of course this is more difficult for larger magnets.
The new superconductors that allow these larger magnets are also very recent, not in discovery but in actual mass production. So they don't have as much experience with using these as with the classical superconductors. So I hope there is still quite some quick improvement there on the table.
These university press releases are always very positively framed. This one makes the new magnet seem incredibly promising and fusion seem like almost an inevitability now, but decades of failure have us conditioned for skepticism. What's the catch this time?
This is D-T fusion. Which means you have to have T. Which currently comes from fission reactor and has a half life of 15 years.
So the plan is to use a molten salt blanket with Be to breed T. But Be isn’t scalable for consumption, so maybe lead eventually. That’s probably do-able, it just slows down the rate new reactors can come online since Pb is not as good a neutron multiplier.
Once they breed extra T, they have to capture and refine it. Hydrogen is very corrosive and hard to work with… and T is radioactive hydrogen. Again, probably doable. But guess what? Refining spent nuclear waste in fission reactors is also do-able. It’s also super expensive.
And they still need a containment vessel that will withstand the wear and tear from sitting next to a mini hydrogen bomb all day.
These challenges are likely all surmountable. But are they surmountable AND cheaper than existing nuclear or other energy sources? Meh?
I'm not sure it's possible for "lay people" (of which I am one) to recognize the difference between a very slow success and "decades of failure".
Very little is invested into fusion power as a project, overall. So advancements seem to come when outside influences cause breakthroughs.
I wonder how different the world would have been if it had for whatever reason been easier to produce fusion power than a fusion bomb. Military investment into the bomb would have probably pushed things forward a lot quicker. As is, the US military built thermonuclear bombs very quickly and then the appetite for advancement just dried up.
Agreed. Whilst it may well be the largest, highest-field "only" high Tc superconductor design in the world, it's definitely not the highest-field high Tc superconducting magnet -- I believe that honour belongs to another bit of MIT with a 1.3 GHz NMR machine [1] (but I do remember something about Bruker collaborating with the US's National Magnet Lab and building a 30T machine -- I can't easily find a link).
I really wish that press release would put the link to the paper at the top -- I found it very hard to work out what was actually new!
I think the framing of what's happened so far as "failure" is probably the main thing responsible for this perception. It's true that progress has been slower than many had hoped and the most optimistic had projected, but "failure" sort suggests that the things the research community have been trying haven't represented meaningful progress towards the goal of power production, which isn't the case.
Q (the ratio of energy out to energy in) has improved by about four orders of magnitude since controlled fusion was first achieved, and it's been a slow, at least reasonably steady march since the middle of the 20th century to achieve that progress. The current record-holding Q for magnetic confinement is around 0.67, so we need well under one more order of magnitude to get to the point of "theoretical break-even" (Q>1) -- we're most of the way there. A plant just barely better than break-even probably wouldn't be commercially viable, though, and while estimates vary, that point is probably somewhere in the 10-30 range, so we have maybe another order of magnitude to go after break-even. I don't think there's anything to suggest that after decades of progress we'll suddenly stop being able to make more.
It's true that things have slowed down somewhat in the last 10-15 years, but most of the blame there goes to the need, in order to continue moving forward, to build bigger and bigger reactors, and the need to divert resources to that goal (mostly ITER). To the extent that promises of going faster have turned out to be hot air, it seems like they've mostly been in the form of novel approaches that do fusion in some fundamental new way that avoids the need to build an ITER-like thing. These approaches seem to often involve lots of unknowns, and end up getting bogged down in practical issues once they're actually tried (surprise plasma instabilities and so on).
Recent advances in materials science (mostly REBCO magnets) and computing, though, offer a path to progress on the regular, bog-standard flavor of magnetic confinement fusion (tokamaks) on a smaller scale -- that's what this is. The nice thing about that is that the plasma physics here are very well understood, and have been heavily researched using conventional/not-super-conducting magnets that won't ever achieve break-even, but create identical plasma conditions inside the reactor (MIT Alcator C-Mod is effectively the conventional-magnet predecessor to this project). Up until now, the only real question was whether or not they could build strong-enough REBCO magnets, and now they have, so this is all good news and reason for optimism.
Of course, commercial viability is a whole other question involving lots of questions besides physics. But the physics here seem to not be in serious doubt, unlike some of the proposals from other startups that are more exotic.
Lots of negative comments in this thread. I've been following CFS for a few years now and I honestly believe this is an historic event - probably the beginning of the "fusion age".
Yeah, any positive news on fusion progress and there always seems to be the same set of comments appear that are overwhelmingly critical of fusion development.
Fusion is not well funded and imo has been let down by mismanagement of ITER, and despite this keeps making progress.
I feel that fusion is one of humanity's best shots at actively reversing climate change, and it is disheartening to see such widespread pessimism about it.
Yeah it's hard. There are huge hurdles in making it economicly viable, but if we can go from first powered flight to the moon in 70 years, and put billions of transistors on a chip in 50, then maybe we can get fusion going. It's clearly possible.
I wouldn't call it that, even if there would be a energy gain.
I call it beginning of "fusion age", when we solved fusion ad can build them reliable and reproducible - and if we still need them by that time, for main energy production.
University press releases need not be peer reviewed so they can get close to saying things that would offend other scientists and get away with it. The key phrase in "the most powerful magnetic field of its kind ever created on Earth" is "of its kind." Creating a many telsa magnetic field has been done in other experiments like with lasers[0], only they are physically smaller in size and last for nanoseconds, it's just of this size, stability and with the high temperature superconductors that makes it special. If the claim is just the magnitude of the field they've already been beat.
Fusion scientist here (no connection with MIT/CFS). This is in fact a very big deal. One of the chief complaints about fusion energy is the low power density (for ITER-like tokamak <<1MW/m^3, vs ~ 100MW/m^3 for a LWR fission core). The low power density is the primary reason that ITER is as large (and hence expensive) as it is.
Fusion power density scales like B^4. So if CFS can get 2x the magnetic field, then they can make the plasma volume 16x smaller, which might equate to big savings in cost and construction time. (It doesn't make sense to go much smaller than their ARC reactor design though -- the plasma already takes up only a fraction of the volume of the core at that scale, so compressing the plasma further doesn't improve the power density. If you can increase the field even more, which REBCO seems to allow, then you would rather just pack more power into a device about the size of ARC. So don't expect to put one of these on your DeLorean.)
There are definitely other challenges/limitations. For one, this approach increases the heat flux that the inner wall of the reactor will have to survive. The localized heat flux of the exhaust stream is expected to rival the heat flux of re-entry from orbit (20 MW/m^2) and could be as high as the power flux from the surface of the sun (~60MW/m^2). 20MW/m^2 is on the hairy edge of what's possible with today's technology, and that's without all the complications of neutron damage, plasma bombardment, etc. The current thinking is to spike the outer layer of the plasma with neon or nitrogen, to radiate most of the power as photons, but there are limitations & risks to that idea as well. Commonwealth's plan for SPARC (last I heard) was to oscillate the exhaust stream back & forth across the absorber plate to reduce the average heat flux.
The nuclear engineering side of fusion has been underfunded for a long time, so there's much that needs to be done on that front, in terms of demonstrating that the breeding of tritium from lithium can be done efficiently & without too much losses. Also, we should be developing better structural materials that can withstand neutron damage & not become (as) radioactive.
It's still very much an open question as to whether fusion could be made economical, even though it seems like it should be technically possible.
In the original proposal for the ARC reactor, they were proposing making the magnet separable so the top and bottom of the reactor could be separated and the vacuum vessel removed. (See pg. 5 of https://library.psfc.mit.edu/catalog/reports/2010/15ja/15ja0...)
It doesn't look like they are targeting that here. Does anyone know if that is ARC (not SPARC) specific, or if that has been abandoned?
The demountable magnets for ARC are so the blanket and vacuum vessel can be swapped out as a whole unit for replacement during maintenance. SPARC has no blanket and will only be used for some thousands of ten second shots or the equivalent of a week or two of continuous operation. The magnets being unshielded will probably fail before the vacuum vessel does.
CFS will be building a lot more magnets, not only for SPARC but for other customers, physics experiments and medical equipment, so I expect they will be working on many additional features including demountable joints for ARC.
One of the early tests they did of the VIPER cable at the SULTAN test facility in Switzerland involved a joint formed by clamping the ends of two cables to a copper bar. It does show that resistive joints are possible with HTS cables, unlike LTS cables, but the actual configuration of a joint for a large magnet is obviously a different matter. Luckily they will have a few years to work on it.
The article says this is from an "MIT-CFS collaboration" which is "on track to build the world’s first fusion device that can create and confine a plasma that produces more energy than it consumes. That demonstration device, called SPARC, is targeted for completion in 2025."
Since there is no actual use planned for any power released in this gadget, no maintenance will be performed. When they finish playing, they scrap it, pocket the money, and go their separate ways.
No commercial reactor will ever be built, so this is just for showing off.
The only real good to come from these efforts is employment of plasma fluid physicists. I just hope non-military work can be found for them when this stuff fizzles. Solar Physics is fascinating and important, but has limited budget.
I've long been skeptical of ITER making any sense given its insane cost. I mean even it succeeds, then what?
Here's the truth: there's no such thing as free energy. Even if the fuel is so abundant it's actually or effectively free (eg deuterium), the energy isn't. Say it takes $50B to build a plant that produces 1GW of power, which I'll estimate at about 7TWh/year based on [1]. Let's also say it has a lifespan of 40 years and an annual maintenance cost of $1B going to up to $2B in the last 10 years.
So that's 40 years for 280TWh at a cost of $100B, which equates to $0.35/kWh if my math is correct.
I realize ITER isn't a commercial power generation project. My point is that people need to stop getting hung up on the fuel being "free". The lifetime cost of the plant can still make it completely economically unviable.
Second, the big weakness of any fusion design is neutrons. The problem people tend to focus on is that neutrons destroy your (very expensive) containment vessel with (one of my favourite terms) "neutron embrittlement".
As an aside, hydrogen fusion also produces high speed helium nuclei, some of which tend to escape and this is a problem too because Helium nuclei are really small so can get in almost any material, which is a whole separate problem.
But here's another factor with neutrons: energy loss. High speed neutrons represent energy lost by the system.
To combat these problems we've looked for alternatives to hydrogen-hydrogen fusion, the holy grail of which is aneutronic fusion. The best candidate for that thus far seems to be Helium-3 fusion but He-3 is exceedingly rare on Earth.
I really think we get caught up on the fact that this is how stars work but stars have a bunch of properties that power plants don't, namely they're really big and they burn their fuel really slowly (as a factor of their size), which is why they can last billions or even trillions of years. Loose neutrons aren't really an issue in a star and sheer size means gravity keeps the whole system contained in a way that magnets just can't (because neutrons ignore magnetic fields).
So I hope they crack fusion but I remain skeptical. Personally I think the most likely future power source is space-based solar power generation.
Your numbers sound like generation 1 numbers, after ITER. ITER is only a test facility to prove hopefully that it can be net positive.
However, those maintenance costs (your estimates) would be the first thing to drop. Any company producing/operating these will be competing with wind and solar, and thus highly incentivized to improve. There should be plenty of low hanging fruit, since it hasn't happened once yet.
Once we've shown this can work successfully, I think people will get excited and investment money will rush in. Ideally, we'll perfect the technology and make it cheaper and more efficient, just like any other technology. If an MIT-borne fusion startup IPOs and they have a working demonstration reactor, I would probably invest.
I think the hope is that with economies of scale, we could build really huge fusion plants one day, and drive down the cost of energy to less than a cent per KWh, and of course completely eliminate our dependency on fossil fuels. If energy becomes that cheap, we could use electricity to produce hydrocarbons from CO2 and water to power airplanes and such. Currently, we can imagine short-distance flights being electrically powered, but transatlantic flights are going to be difficult to achieve with batteries.
Space based power generation to me is incredibly dumb. It would be far easier to build solar on earth and transport it around with high efficiency DC lines.
And if you are really looking into the cheapest possible energy a thorium breeder reactor could run for ever with no fuel cost and could be built with 70s technology. These reactor be produced in a factory at a manufacturing line and then dropped into a containment facility.
How this should be more expensive then space based solar makes no sense to me.
Question from a layman: how will the energy from a fusion reactor be extracted and converted into electrical energy? As far as I understand, the plasma inside a tokamak is isolated from the surroundings by the use of very powerful magnets. I assume in a reactor that is supposed to generate electricity there would be some interface between the plasma and some kind of heat exchanger that would generate steam and turn gas turbines?
Neutrons that escape the tokamak arrive in a lithium mantle around the reactor, which produces helium and some heat. The heat is extracted from the lithium mantle, and then you have a conventional gas turbine.
This is what I remember from memory, I would need to fact check that.
Fusion is on my plate too. I've got a design that I really need to test, an I've finally got the funds to begin construction.
My method uses much lower magnetic fields that could be provided by permanent magnets, but should allow containment times on the order of weeks for small quantities of D-D fuel.
In case others are wondering, looks like this is for SPARC.
FTA: This "MIT-CFS collaboration...on track to build the world’s first fusion device that can create and confine a plasma that produces more energy than it consumes. That demonstration device, called SPARC, is targeted for completion in 2025."
The magnets are a problem to solve, but not the biggest problem by far. Solve for neutron embrittlement of the reactor parts, and then you’ll start to have some credibility.
The advances enable a magnetic field strength that would otherwise require 40x more volume using conventional technology - doesn’t the reduced volume imply the plasma temperature would also increase significantly? Or is the magnetic field strong enough to protect the walls of the chamber?
If you compress something so much that its nuclei want to fuse, it must become very dense. At the core of this compression, density is intense. Unlike a thermonuclear weapon where the compression is transient, there is no release from this nuclear vise. Pressures would radically rise increasing compression even further. Would the gravitational field in the vicinity of the center of this be equally intense? Could black holes on the order of the Planck scale be created? Would such a 'Planck hole' start a chain reaction of gravitational collapse, eventually growing to consume our solar system?
They seem to have made two claims. First, that they have a qualitatively different design that requires a significantly stronger magnetic field. Second, that they could build a magnet that produces such a field.
They are now claiming to have done the latter. Are you skeptical of the new design? Or do you think it does not represent as significant a departure from earlier designs as they claim?
As a society we have failed to really use fission. Fission does basically everything fusion promises to do.
Fission has a absurdly high energy density, the step from oil to fission is far more relevant then the step from fission to fusion.
Fusion would mean basically no fuel cost, but thorium is already a waste product and even uranium fuel is a tiny part of any fission plant.
Some people seem to believe the fusion is inherently prove against weapons, but this is equally not really true. If you had a working fission plant there would be ways to use it to get what you want to make a weapon.
There are some places you might want fusion, mainly in space travel but even there we are not anywhere even close to where we could get to with fission. Open gas nuclear thermal rockets anybody?
In sum, I'm not against this reseach but its not a way to solve our problems anytime soon. Fission you could get to run with 60s tech and amazing reactors could be designed within decades and often with comparatively small teams in the 60-80s and somehow we haven't managed to make it competitive.
Fusion looks to be far more complex to build in every possible way. How this will be cheaper is questionable to me.
SPARC is an amazing project. Congrats on this milestone! I am optimistic about SPARC and ARC. I'd love to hear legitimate critiques, though. I see a lot of negative comments on ITER, which is a very different situation. ITER will teach us a great deal btw, it isn't a waste of time.
These high magnetic fields are generated using flux compression[0], in which the incompressibility of magnetic field lines means that compressing the coils generating the magnetic fields will increase the strength of the resultant magnetic field. However, the implosion process permanently destroys the magnet, which makes it highly unsuitable for continuous use and certainly shouldn't be used anywhere near your fusion reactor.
1200 T has a magnetic pressure of about 5.7 megabars (about 20x the detonation pressure of high explosives). Such high fields can only be achieved very briefly in devices that explosively disassemble.
From a economical/political point of view I find very interesting and promising that CFS is participated, amongst others, by one of the largest oil company in the world (ENI), which signal a real effort to move away, or at least strongly differentiate, from fossil fuels.
It's nice to see another promising avenue. The Wendelstein 7-X (a Stellerator) design is the other one that I'm particularly interested in. I believe it met its initial goals and is now in a multi-year refit before attempting continuous operation.
Every mass-media article on fusion seems obliged to use "the fuel comes from water" line. I wonder if a "just says in mice" style harassment campaign would get journalists to stop saying this.
The journalists are saying that because the PR people tell them that. If I were doing PR for a fusion project, I'd sell that aspect hard—it's technically true, and sounds great.
Journalists quote promoters. When something has no reasonable prospect of ever producing, promoters resort to lying. Journalists are not responsible for it, although experience should make them less credulous. But pie in the sky sells better than skepticism.
A bit off-topic but it feel like the right time to ask, does anyone recommend some video or even book to understand the fusion space better as a non-physicist?
MIT is also the origin of Transatomic Power which went belly up after they discovered that an early math mistake meant that their whole plan was bunkus, so evaluate this on its own merits rather than assigning any halo points from the MIT name.
Even if we can get fusion to work, it will never be economical. Just because the fuel (water) is free, that doesn't make the energy free. The fuel rods for fission power plants are already a rounding error in the cost of energy. It's the capital costs that dominate the equation, and fusion plants will be at least as expensive as fission, which is more expensive per KWh than solar.
If we had "an inexhaustible, carbon-free source of energy that you can deploy anywhere and at any time" we'd wreck the planet faster than we already are... I guess at least a few could escape though.
I'm curious whether we could cool the planet by pulling CO2 out of the air with scrubbers powered by fusion reactors, or if their heat output would cancel it out. Removing the CO2 would have the benefit of being an exponential thermal decrease (the planet gets less hot from the sun each day), and heat output from fusion plants should scale linearly with the rate at which the CO2 scrubbers run, so it's possible the scaling properties would work out...
Some comments were deferred for faster rendering.
dfdx|4 years ago
Fusion energy was actually making rapid progress in the latter half of the twentieth century, going from almost no power output in the fifties and sixties to a power output equal to 67% of input power with the JET reactor in 1997. By the eighties there was plenty of experimental evidence to describe the relationships between tokamak parameters and power output. Particularly that the gain is proportional to the radius to the power of 1.3 and the magnetic field cubed. The main caveat to this relationship was that we only had magnets that would go up to 5.5 Tesla, which implied we needed a tokamak radius of 6 meters or so in order to produce net energy.
Well that 6 meter tokamak was designed in the eighties and is currently under construction. ITER, being so large, costs tens of billions of dollars and requires international collaboration; the size of the project has led to huge budget overruns and long delays. Recently however, there have been significant advances in high-temperature super conductors that can produce magnetic fields large enough that we (theoretically) only need a tokamak with a major radius of about 1.5 meters to produce net gain. This is where SPARC (the tokamak being built by the company in the article) comes in. The general idea is that since we have stronger magnets now, we can make a smaller, and therefore cheaper tokamak quickly.
Small tokamaks do have downsides, namely that the heat flux through the walls of the device is so large that it will damage the tokamak. There have been breakthroughs with various divertor designs that can mitigate this, but to the best of my knowledge I'm not sure that CFS has specified their divertor configuration.
This was just a short summary of the presentation by Dennis Whyte given here [0]. I do not work in the fusion community.
[0] https://www.youtube.com/watch?v=KkpqA8yG9T4
mchusma|4 years ago
-Fusion has made consistent improvement, roughly in line with expectations for the level of investment (20 years away predictions were considering if we invested massively, which we did not).
- Fusion is in theory something that could give us true energy abundance. Want to just desalinate water like crazy? Want to extract gigatons of carbon? Working fusion enables these to happen woth existing technologies.
I like to think of solar, batteries, fission, and wind as compelling ways to go mostly carbon free and lower energy costs about 2x over the next 20 years or so.
Fusion is what reduces energy cost potentially another 10x, which really changes the game for lots of things. Exciting stuff. Kudos to this team.
zetalyrae|4 years ago
It just doesn't strike me as obvious that reducing the major radius by a few meters would have such a huge impact on cost/timelines.
sigmoid10|4 years ago
It's not that simple. The big problem with magnetic confinement fusion is that you need to control turbulence in the plasma so that you can contain the reactions for a reasonable amount of time to extract useful energy. However, turbulence increases with stronger magnetic field gradients, which is exactly what you get when making a smaller reactor chamber with stronger magnets. This wouldn't be the first project claiming to be able to build a small reactor, only to discover that it's virtually impossible without a major theoretical breakthrough. This is usually left out in the venture capital advertisements for these fusion startups. There's a reason why so much money and effort is spent on ITER - it is the only more or less guaranteed path to fusion with the tech and knowledge we have today.
bell-cot|4 years ago
Maybe your equations and power laws are right, and a "big enough" tokamak would be a competitive source of power. But then there are the details, like "big enough will cost $25 Trillion". Followed by delays, cost overruns, etc.
I'm thinking that a rational, non-expert taxpayer would say, "This fusion thing is a hundred times worse than NASA's Senate Launch System. Stop wasting my money on it NOW, and let gullible investors waste theirs instead."
yboris|4 years ago
https://www.youtube.com/watch?v=rY6U4wB-oYM
ArtWomb|4 years ago
VIPER: an industrially scalable high-current high-temperature superconductor cable
https://iopscience.iop.org/article/10.1088/1361-6668/abb8c0
tsimionescu|4 years ago
Most notably, the extreme temperatures, hydrogen pumping, and high-energy neutron bombardment mean that, even with liquid metal blankets, the reactors will very quickly become brittle, probably not lasting more than a year or two. Since neutron bombardment also turns any material radioactive, not only do you need to tear down your fusion plant (or at least the expensive reactor part of it) every few years, but you have to do it with radiation-resistant robots, as human workers can't get close to the reactor after it's been operating for a while.
https://thebulletin.org/fusion-energy-nuclear-fusion/
causality0|4 years ago
vmception|4 years ago
A whole generation heard about it in school decades ago. Multiple generations by now, even. Its right up there with battery/energy-storage technologies. Headline after headline, enrapturing a newer and newer idealist set of people to quickly become disillusioned. People just get tired of it.
But I’m glad to understand whats going on behind the scenes now. I’ll pay attention. Looks like a real sleeper.
TrainedMonkey|4 years ago
So, why is this particular announcement exciting? There are 3 factors:
1. This is a high temperature superconductor. I can't find any references, but as far as I remember the substrate they are using needs to be cooled to (WRONG, it was cooled to 20degK, see reply by MauranKilom) 60-70 degK to achieve super conductivity. Compare to magnets used in ITER which need to be cooled to 4degK. This is the difference between using relatively cheap liquid nitrogen vs liquid helium.
2. Field strength of 20 Tesla is significantly higher than 13 Tesla used in ITER. Given that magnetic confinement fusion scales significantly better with field strength vs reactor size, this will enable much smaller reactor to be power positive. See following links for more details on ITERs magnets: https://www.newscientist.com/article/2280763-worlds-most-pow... https://www.iter.org/newsline/-/2700
3. Finally, the magnet was assembled from 16 identical subassemblies, each of which used mass manufactured magnetic tape. This is significantly cheaper and more scalable than custom magnet design/manufacturing used by ITER.
The kicker is how 3 of the factors above interact with the cost of the project. Stronger magnets allow smaller viable reactors. High temperature superconductors + smaller reactors allow for a much simpler and smaller cooling system. Smaller reactors + scalable magnet design further drives down the cost. Finally, cost of state of art mega projects scales somewhere between 3rd and 4th power with the size of the device. Combining all of the above factors, SPARC should be here significantly sooner than ITER and cost a tiny fraction (I would guesstimate that fraction to be between 1/100 and 1/10,000).
edit: typos + looked at the cost of ITER and refined my cost fraction guesstimate + corrected some stuff based on the reply by MauranKilom.
MauranKilom|4 years ago
> This is because energy gain and power density scale exponentially with magnetic field strength but only linearly with reactor size
Nit: It scales polynomially, not exponentially. Specifically (according to those formulas) energy gain scales with the cube of field strength and power density with the fourth power. Still massive scaling indeed, but exponentially would be something else.
> as far as I remember the substrate they are using needs to be cooled to 60-70 degK to achieve super conductivity
The video in the article shows 20 K. Could of course be that higher temperature is feasible and they just played it safe (or the video is wrong).
choeger|4 years ago
But they don't need to, do they? If their claim is sound, they could as well just optimize the magnets and wait for ITER to complete to offer an ITERation (pun very much intended) on the design. The fact that they focus on this weird race against an international research project makes me wonder if SPARC is mostly a vehicle to attract investors.
fabian2k|4 years ago
The new superconductors that allow these larger magnets are also very recent, not in discovery but in actual mass production. So they don't have as much experience with using these as with the classical superconductors. So I hope there is still quite some quick improvement there on the table.
shmageggy|4 years ago
anonuser123456|4 years ago
This is D-T fusion. Which means you have to have T. Which currently comes from fission reactor and has a half life of 15 years.
So the plan is to use a molten salt blanket with Be to breed T. But Be isn’t scalable for consumption, so maybe lead eventually. That’s probably do-able, it just slows down the rate new reactors can come online since Pb is not as good a neutron multiplier.
Once they breed extra T, they have to capture and refine it. Hydrogen is very corrosive and hard to work with… and T is radioactive hydrogen. Again, probably doable. But guess what? Refining spent nuclear waste in fission reactors is also do-able. It’s also super expensive.
And they still need a containment vessel that will withstand the wear and tear from sitting next to a mini hydrogen bomb all day.
These challenges are likely all surmountable. But are they surmountable AND cheaper than existing nuclear or other energy sources? Meh?
stormbrew|4 years ago
Very little is invested into fusion power as a project, overall. So advancements seem to come when outside influences cause breakthroughs.
I wonder how different the world would have been if it had for whatever reason been easier to produce fusion power than a fusion bomb. Military investment into the bomb would have probably pushed things forward a lot quicker. As is, the US military built thermonuclear bombs very quickly and then the appetite for advancement just dried up.
azalemeth|4 years ago
I really wish that press release would put the link to the paper at the top -- I found it very hard to work out what was actually new!
[1] https://ieeexplore.ieee.org/document/6926794
apendleton|4 years ago
Q (the ratio of energy out to energy in) has improved by about four orders of magnitude since controlled fusion was first achieved, and it's been a slow, at least reasonably steady march since the middle of the 20th century to achieve that progress. The current record-holding Q for magnetic confinement is around 0.67, so we need well under one more order of magnitude to get to the point of "theoretical break-even" (Q>1) -- we're most of the way there. A plant just barely better than break-even probably wouldn't be commercially viable, though, and while estimates vary, that point is probably somewhere in the 10-30 range, so we have maybe another order of magnitude to go after break-even. I don't think there's anything to suggest that after decades of progress we'll suddenly stop being able to make more.
It's true that things have slowed down somewhat in the last 10-15 years, but most of the blame there goes to the need, in order to continue moving forward, to build bigger and bigger reactors, and the need to divert resources to that goal (mostly ITER). To the extent that promises of going faster have turned out to be hot air, it seems like they've mostly been in the form of novel approaches that do fusion in some fundamental new way that avoids the need to build an ITER-like thing. These approaches seem to often involve lots of unknowns, and end up getting bogged down in practical issues once they're actually tried (surprise plasma instabilities and so on).
Recent advances in materials science (mostly REBCO magnets) and computing, though, offer a path to progress on the regular, bog-standard flavor of magnetic confinement fusion (tokamaks) on a smaller scale -- that's what this is. The nice thing about that is that the plasma physics here are very well understood, and have been heavily researched using conventional/not-super-conducting magnets that won't ever achieve break-even, but create identical plasma conditions inside the reactor (MIT Alcator C-Mod is effectively the conventional-magnet predecessor to this project). Up until now, the only real question was whether or not they could build strong-enough REBCO magnets, and now they have, so this is all good news and reason for optimism.
Of course, commercial viability is a whole other question involving lots of questions besides physics. But the physics here seem to not be in serious doubt, unlike some of the proposals from other startups that are more exotic.
phkahler|4 years ago
There are a bunch of issues still to be resolved. Higher magnet strength is/was just one of many.
unknown|4 years ago
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jcfrei|4 years ago
phscguy|4 years ago
I feel that fusion is one of humanity's best shots at actively reversing climate change, and it is disheartening to see such widespread pessimism about it. Yeah it's hard. There are huge hurdles in making it economicly viable, but if we can go from first powered flight to the moon in 70 years, and put billions of transistors on a chip in 50, then maybe we can get fusion going. It's clearly possible.
hutzlibu|4 years ago
I wouldn't call it that, even if there would be a energy gain.
I call it beginning of "fusion age", when we solved fusion ad can build them reliable and reproducible - and if we still need them by that time, for main energy production.
phendrenad2|4 years ago
noobermin|4 years ago
[0] https://www.nature.com/articles/s41467-017-02641-7
Just as a note, the max B field here is 600T
zardo|4 years ago
https://nationalmaglab.org/news-events/news/lbc-project-worl...
lambdatronics|4 years ago
Fusion power density scales like B^4. So if CFS can get 2x the magnetic field, then they can make the plasma volume 16x smaller, which might equate to big savings in cost and construction time. (It doesn't make sense to go much smaller than their ARC reactor design though -- the plasma already takes up only a fraction of the volume of the core at that scale, so compressing the plasma further doesn't improve the power density. If you can increase the field even more, which REBCO seems to allow, then you would rather just pack more power into a device about the size of ARC. So don't expect to put one of these on your DeLorean.)
There are definitely other challenges/limitations. For one, this approach increases the heat flux that the inner wall of the reactor will have to survive. The localized heat flux of the exhaust stream is expected to rival the heat flux of re-entry from orbit (20 MW/m^2) and could be as high as the power flux from the surface of the sun (~60MW/m^2). 20MW/m^2 is on the hairy edge of what's possible with today's technology, and that's without all the complications of neutron damage, plasma bombardment, etc. The current thinking is to spike the outer layer of the plasma with neon or nitrogen, to radiate most of the power as photons, but there are limitations & risks to that idea as well. Commonwealth's plan for SPARC (last I heard) was to oscillate the exhaust stream back & forth across the absorber plate to reduce the average heat flux.
The nuclear engineering side of fusion has been underfunded for a long time, so there's much that needs to be done on that front, in terms of demonstrating that the breeding of tritium from lithium can be done efficiently & without too much losses. Also, we should be developing better structural materials that can withstand neutron damage & not become (as) radioactive.
It's still very much an open question as to whether fusion could be made economical, even though it seems like it should be technically possible.
sdeyerle|4 years ago
It doesn't look like they are targeting that here. Does anyone know if that is ARC (not SPARC) specific, or if that has been abandoned?
baking|4 years ago
CFS will be building a lot more magnets, not only for SPARC but for other customers, physics experiments and medical equipment, so I expect they will be working on many additional features including demountable joints for ARC.
One of the early tests they did of the VIPER cable at the SULTAN test facility in Switzerland involved a joint formed by clamping the ends of two cables to a copper bar. It does show that resistive joints are possible with HTS cables, unlike LTS cables, but the actual configuration of a joint for a large magnet is obviously a different matter. Luckily they will have a few years to work on it.
nielsbot|4 years ago
So, sounds like it's for SPARC.
unknown|4 years ago
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elihu|4 years ago
ncmncm|4 years ago
No commercial reactor will ever be built, so this is just for showing off.
The only real good to come from these efforts is employment of plasma fluid physicists. I just hope non-military work can be found for them when this stuff fizzles. Solar Physics is fascinating and important, but has limited budget.
cletus|4 years ago
Here's the truth: there's no such thing as free energy. Even if the fuel is so abundant it's actually or effectively free (eg deuterium), the energy isn't. Say it takes $50B to build a plant that produces 1GW of power, which I'll estimate at about 7TWh/year based on [1]. Let's also say it has a lifespan of 40 years and an annual maintenance cost of $1B going to up to $2B in the last 10 years.
So that's 40 years for 280TWh at a cost of $100B, which equates to $0.35/kWh if my math is correct.
I realize ITER isn't a commercial power generation project. My point is that people need to stop getting hung up on the fuel being "free". The lifetime cost of the plant can still make it completely economically unviable.
Second, the big weakness of any fusion design is neutrons. The problem people tend to focus on is that neutrons destroy your (very expensive) containment vessel with (one of my favourite terms) "neutron embrittlement".
As an aside, hydrogen fusion also produces high speed helium nuclei, some of which tend to escape and this is a problem too because Helium nuclei are really small so can get in almost any material, which is a whole separate problem.
But here's another factor with neutrons: energy loss. High speed neutrons represent energy lost by the system.
To combat these problems we've looked for alternatives to hydrogen-hydrogen fusion, the holy grail of which is aneutronic fusion. The best candidate for that thus far seems to be Helium-3 fusion but He-3 is exceedingly rare on Earth.
I really think we get caught up on the fact that this is how stars work but stars have a bunch of properties that power plants don't, namely they're really big and they burn their fuel really slowly (as a factor of their size), which is why they can last billions or even trillions of years. Loose neutrons aren't really an issue in a star and sheer size means gravity keeps the whole system contained in a way that magnets just can't (because neutrons ignore magnetic fields).
So I hope they crack fusion but I remain skeptical. Personally I think the most likely future power source is space-based solar power generation.
[1]: https://en.wikipedia.org/wiki/List_of_largest_power_stations
mLuby|4 years ago
Space-based solar power generation (itself "fusion power" in the loosest sense) would be great in the inner planets.
Though to open up the outer planets, Kuiper belt, Oort Cloud, and any other stars, we'll need non-solar* power: hopefully fusion, at least fission.
*Unless we want to go the stellaser route, but I'd bet we'll crack fusion before getting near K2.
gibolt|4 years ago
However, those maintenance costs (your estimates) would be the first thing to drop. Any company producing/operating these will be competing with wind and solar, and thus highly incentivized to improve. There should be plenty of low hanging fruit, since it hasn't happened once yet.
snek_case|4 years ago
I think the hope is that with economies of scale, we could build really huge fusion plants one day, and drive down the cost of energy to less than a cent per KWh, and of course completely eliminate our dependency on fossil fuels. If energy becomes that cheap, we could use electricity to produce hydrocarbons from CO2 and water to power airplanes and such. Currently, we can imagine short-distance flights being electrically powered, but transatlantic flights are going to be difficult to achieve with batteries.
nickik|4 years ago
Space based power generation to me is incredibly dumb. It would be far easier to build solar on earth and transport it around with high efficiency DC lines.
And if you are really looking into the cheapest possible energy a thorium breeder reactor could run for ever with no fuel cost and could be built with 70s technology. These reactor be produced in a factory at a manufacturing line and then dropped into a containment facility.
How this should be more expensive then space based solar makes no sense to me.
sdenton4|4 years ago
oseityphelysiol|4 years ago
jokteur|4 years ago
This is what I remember from memory, I would need to fact check that.
tsimionescu|4 years ago
pontifier|4 years ago
My method uses much lower magnetic fields that could be provided by permanent magnets, but should allow containment times on the order of weeks for small quantities of D-D fuel.
I have more information at http://www.DDproFusion.com
dmix|4 years ago
rpmisms|4 years ago
nielsbot|4 years ago
In case others are wondering, looks like this is for SPARC.
FTA: This "MIT-CFS collaboration...on track to build the world’s first fusion device that can create and confine a plasma that produces more energy than it consumes. That demonstration device, called SPARC, is targeted for completion in 2025."
CFS: https://cfs.energy/technology
(edit: clarification)
john_yaya|4 years ago
criticaltinker|4 years ago
tppiotrowski|4 years ago
ITER was designed to use weaker electromagnets and therefore needs a massive building and tons of cranes and a massive budget.
bawana|4 years ago
dfdz|4 years ago
Smaller. Smarter. Sooner. 2018
Currently 2021 where is my fusion energy? But this time must be different, after this advance we are only a few years away from fusion energy?
bwestergard|4 years ago
They are now claiming to have done the latter. Are you skeptical of the new design? Or do you think it does not represent as significant a departure from earlier designs as they claim?
ChrisMarshallNY|4 years ago
I really want this to work. I am a bit concerned, with how “the old guard” will react, once we have successful, productive, fusion.
I foresee an astroturf NIMBY campaign against construction of fusion plants.
baking|4 years ago
The goal is to get fusion power om the grid in the 2030's and scale up in the 2040's. Stop moving the goalposts.
Seanambers|4 years ago
The video thouches upon magnetic fields and its relevance at this time mark ; https://youtu.be/L0KuAx1COEk?t=2880
nickik|4 years ago
Fission has a absurdly high energy density, the step from oil to fission is far more relevant then the step from fission to fusion.
Fusion would mean basically no fuel cost, but thorium is already a waste product and even uranium fuel is a tiny part of any fission plant.
Some people seem to believe the fusion is inherently prove against weapons, but this is equally not really true. If you had a working fission plant there would be ways to use it to get what you want to make a weapon.
There are some places you might want fusion, mainly in space travel but even there we are not anywhere even close to where we could get to with fission. Open gas nuclear thermal rockets anybody?
In sum, I'm not against this reseach but its not a way to solve our problems anytime soon. Fission you could get to run with 60s tech and amazing reactors could be designed within decades and often with comparatively small teams in the 60-80s and somehow we haven't managed to make it competitive.
Fusion looks to be far more complex to build in every possible way. How this will be cheaper is questionable to me.
mzs|4 years ago
derac|4 years ago
sc0ttyd|4 years ago
Haven't Tokamak Energy in the UK done better than this already back in 2019 with their 24T magnet based on similar HTS tape technology?
https://www.tokamakenergy.co.uk/tokamak-energy-exceeds-targe...
unknown|4 years ago
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NiceWayToDoIT|4 years ago
In comparison, 20T does not look much, but again it is, I wonder with the Japanese technique what is the highest continuous magnetic field.
uj8efdjkfdshf|4 years ago
[0] https://en.wikipedia.org/wiki/Explosively_pumped_flux_compre...
pfdietz|4 years ago
phtrivier|4 years ago
And I hope the marketers pretending they'll have a commercial plant by 2025 are ashamed.
ghego1|4 years ago
rkangel|4 years ago
kgarten|4 years ago
sbierwagen|4 years ago
rpmisms|4 years ago
ncmncm|4 years ago
m3at|4 years ago
pjmanroe|4 years ago
pjmanroe|4 years ago
Mizza|4 years ago
For instance, can I build a railgun to shoot things into orbit?
shsbdncudx|4 years ago
spoonjim|4 years ago
joelthelion|4 years ago
unknown|4 years ago
[deleted]
fnord77|4 years ago
HPMOR|4 years ago
pjmanroe|4 years ago
RandyGoldy|4 years ago
[deleted]
marsven_422|4 years ago
[deleted]
FredPret|4 years ago
garbagecoder|4 years ago
xqcgrek2|4 years ago
Nah.
pjmanroe|4 years ago
freeopinion|4 years ago
JDDunn9|4 years ago
https://thebulletin.org/2017/04/fusion-reactors-not-what-the...
gfodor|4 years ago
pcj-github|4 years ago
maccam94|4 years ago