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.<p>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.<p>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.<p>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.<p>This was just a short summary of the presentation by Dennis Whyte given here [0]. I do not work in the fusion community.<p>[0] <a href="https://www.youtube.com/watch?v=KkpqA8yG9T4" rel="nofollow">https://www.youtube.com/watch?v=KkpqA8yG9T4</a>
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: <a href="https://youtu.be/xJ2h3vbOag4?t=306" rel="nofollow">https://youtu.be/xJ2h3vbOag4?t=306</a><p>So, why is this particular announcement exciting? There are 3 factors:<p>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.<p>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: <a href="https://www.newscientist.com/article/2280763-worlds-most-powerful-magnet-being-shipped-to-iter-fusion-reactor/" rel="nofollow">https://www.newscientist.com/article/2280763-worlds-most-pow...</a> <a href="https://www.iter.org/newsline/-/2700" rel="nofollow">https://www.iter.org/newsline/-/2700</a><p>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.<p>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).<p>edit: typos + looked at the cost of ITER and refined my cost fraction guesstimate + corrected some stuff based on the reply by MauranKilom.
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?
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".
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.<p>[0] <a href="https://www.nature.com/articles/s41467-017-02641-7" rel="nofollow">https://www.nature.com/articles/s41467-017-02641-7</a><p>Just as a note, the max B field here is 600T
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.<p>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.)<p>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.<p>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.<p>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 <a href="https://library.psfc.mit.edu/catalog/reports/2010/15ja/15ja032/15ja032_full.pdf" rel="nofollow">https://library.psfc.mit.edu/catalog/reports/2010/15ja/15ja0...</a>)<p>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?
I've long been skeptical of ITER making any sense given its insane cost. I mean even it succeeds, then what?<p>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.<p>So that's 40 years for 280TWh at a cost of $100B, which equates to $0.35/kWh if my math is correct.<p>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.<p>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".<p>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.<p>But here's another factor with neutrons: energy loss. High speed neutrons represent energy lost by the system.<p>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.<p>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).<p>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.<p>[1]: <a href="https://en.wikipedia.org/wiki/List_of_largest_power_stations" rel="nofollow">https://en.wikipedia.org/wiki/List_of_largest_power_stations</a>
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?
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.<p>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.<p>I have more information at <a href="http://www.DDproFusion.com" rel="nofollow">http://www.DDproFusion.com</a>
Update: They have a press release on their website <a href="https://cfs.energy/news-and-media/cfs-commercial-fusion-power-with-hts-magnet" rel="nofollow">https://cfs.energy/news-and-media/cfs-commercial-fusion-powe...</a><p>In case others are wondering, looks like this is for SPARC.<p>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."<p>CFS: <a href="https://cfs.energy/technology" rel="nofollow">https://cfs.energy/technology</a><p>(edit: clarification)
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?
The thumbnail of the youtube video made me laugh<p>Smaller. Smarter. Sooner. 2018<p>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?
If anyone have not seen it i recommend this video as a primer for fusion technology, it's from MIT.
<a href="https://www.youtube.com/watch?v=L0KuAx1COEk" rel="nofollow">https://www.youtube.com/watch?v=L0KuAx1COEk</a><p>The video thouches upon magnetic fields and its relevance at this time mark ; <a href="https://youtu.be/L0KuAx1COEk?t=2880" rel="nofollow">https://youtu.be/L0KuAx1COEk?t=2880</a>
As a society we have failed to really use fission. Fission does basically everything fusion promises to do.<p>Fission has a absurdly high energy density, the step from oil to fission is far more relevant then the step from fission to fusion.<p>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.<p>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.<p>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?<p>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.<p>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.
The claim is that they have reached "a field strength of 20 tesla, the most powerful magnetic field of its kind ever created on Earth"<p>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?<p><a href="https://www.tokamakenergy.co.uk/tokamak-energy-exceeds-target-of-20-tesla-with-hts-magnets/" rel="nofollow">https://www.tokamakenergy.co.uk/tokamak-energy-exceeds-targe...</a>
I remembered that in 2018 Japanese team manage 1200 T peak power.
<a href="http://www.sci-news.com/physics/strongest-magnetic-field-achieved-indoors-06420.html" rel="nofollow">http://www.sci-news.com/physics/strongest-magnetic-field-ach...</a><p>In comparison, 20T does not look much, but again it is, I wonder with the Japanese technique what is the highest continuous magnetic field.
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.
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 <i>as a non-physicist</i>?
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.<p><a href="https://thebulletin.org/2017/04/fusion-reactors-not-what-theyre-cracked-up-to-be/" rel="nofollow">https://thebulletin.org/2017/04/fusion-reactors-not-what-the...</a>
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.