Nuclear fusion startup raises $100M to design and build a demo power plant
bloomberg.com
bloomberg.com
The whole article is just about this press release:
https://generalfusion.com/2019/12/general-fusion-closes-65m-...
“General Fusion Closes $65M of Series E Financing“
https://en.wikipedia.org/wiki/ITER
"If ITER becomes operational, it will become the largest magnetic confinement plasma physics experiment in use with a plasma volume of 840 cubic meters,[15] surpassing the Joint European Torus by almost a factor of 10."
I fail to find any hint to a reasonable estimation of viability of General Fusion's concept.
Edit: and I mean a written estimation, not that they will now, with the received money, according to their own words, just "formally launch the program" (note they promise just to formally launch the program, nothing more) "to design, construct, and subsequently operate its Fusion Demonstration Plant." Heh.
And hence the reason they are wanting to build a working prototype.
They have a conceptual model that needs to be tested.
What I don't understand is why the WX-7 looks nothing like ITER. The people putting together WX-7 evidently thought that these convolutions were required, yet the ITER group does not. The race is not simple!
"purpose is to advance stellarator technology, though this experimental reactor will not produce electricity, it is used to evaluate the main components of a future fusion power plant"
https://en.wikipedia.org/wiki/Wendelstein_7-X
To compare, even ITER, international nuclear fusion research and engineering megaproject, initiated in 1988 (!) will also not produce any electrical energy:
"ITER will not capture the energy it produces as electricity, but—as first of all fusion experiments in history to produce net energy gain—it will prepare the way for the machine that can."
https://www.iter.org/proj/inafewlines
The net energy "gained" in ITER experiment, if it achieves that much, will be just "vented to the atmosphere." The other experiments don't even expect to have any gain.
https://en.wikipedia.org/wiki/ITER
The smallest possible promise is, of course, that the money received "enables the Company to formally launch the program" as in the "news" here:
https://generalfusion.com/2019/12/general-fusion-closes-65m-...
They're just two different ways to solve the same problem. If you confine a plasma in a symmetric toroidal field, the difference in field strength between the inner and outer edges of the torus cause the electrons and protons in the field to separate. This causes a buildup of huge voltages in the plasma, causing a breakdown in the magnetic field.
A stellarator fixes this by twisting the plasma loop into a figure 8 pattern that causes electrons and protons to twist and loop round the plasma path and roughly cancel out the voltages, not quite, but close. A tokamak confines the particles in a torroidal field, but winds the magnetic field lines round the torus in a helical pattern.
That's actually not obvious at all. ITER project was started 12 years ago. By now it's very likely that there are ways to do it cheaper. But what do you do? Abandon the partially built ITER and start over? And what do you do if 5 years from now there are ways to build it cheaper still? So the government bureaucracies are marching on to complete it, which IMO is a sensible thing to do. But it doesn't mean it can't be done cheaper or more simply with 2020 technology.
https://en.wikipedia.org/wiki/Sonoluminescence
Since fluids are approximately incompressible, they can concentrate a tremendous amount of pressure and heat in a small space when rammed together with no route for escape:
https://en.wikipedia.org/wiki/Water_hammer
Since we know that the hydrogen in water will fuse on its own under enough pressure, we can run the calculation using the water hammer formula;
maximum pressure = 0.0135 * velocity * length / time
https://en.wikipedia.org/wiki/Solar_core
If we use a length of 1 meter, and velocity of 1 meter per second, we can see what compression time is required to achieve the pressure at the core of the sun using a water hammer:
2.65e16 = 0.0135 * 1 * 1 / time
time = 0.0135 * 1 * 1 / 26.5e15 = 5.09e-19 seconds
time = 0.1539 * 1 * 1 / 26.5e15 = 5.81e-18 seconds
time = 0.1539 * 10 * 10 / 26.5e15 = 5.81e-16 seconds
So this is the maximum time that the liquid must remain compressed at the center without finding a way out (via quantum tunneling or something, who knows at these extremes) in order to reach the desired pressure. I don’t know if the shape of the bubble needs to be spherical or if any geometry works. I also don’t know how temperature affects it (the temperature will likely be higher than for sonoluminescence since the bubble is bigger). But we do know that the general idea works, because fusion bombs are ignited by a fission bomb compressing hydrogen to the necessary heat and pressure.
The main problem will be with the hydrogen plasma diffusing into the metal. But since pressure falls off gradually from the center, the cross section should be large enough that it may not pose much of an issue. I also wonder if the presence of the metal atoms might create smaller channels through which the hydrogen must pass. That would take advantage of the electromagnetic force holding atoms apart, similarly to how magnetic confinement works in a Tokamak or Farnsworth Fusor, and create pinch points where atoms are more likely to fuse.
The final reactor design should probably use liquid hydrogen because a bigger cross section could fuse, because the P=pLv/t formula is linear. F=ma means that lighter atoms accelerate linearly faster under the same force, but also decrease final pressure linearly. So if my math is right, final pressure should be within the same order of magnitude for all atoms (hopefully someone can check this). For example, liquid hydrogen has a density of 0.07 grams per cubic centimeter, so is 14.29 times less dense than water, so the final V for liquid hydrogen should be about 14.29 times higher than water and 14.28 * 11.4 = 162.9 times higher than lead. But final pressure would be 14.29 and 162.9 times lower respectively so result in nearly the same maximum pressure.
Also they should tune the geometry so that the 1 second firing rate matches the bounce frequency of the liquid.
Thermodynamic efficiency probably won’t be great at first, with the Carnot limit of:
https://en.wikipedia.org/wiki/Carnot%27s_theorem_(thermodyna...
efficiency = 1 - (cold temperature)/(hot temperature)
Maybe the first reactor design gets 10% of unity, maybe the second one gets 20%. It will be interesting to see the final formula for reactor size vs gain factor (Q), because then we’ll know if it can simply be scaled up by a few orders of magnitude or if something in the physics prevents it from working if it’s smaller than a star. Of course this principle is the same for any fusion reactor. Wouldn’t it be wonderful if they find that all that matters is the strength of the pistons and that the reactor can be scaled down to fit in a shipping container, just running at a higher frequency!
My gut feeling is that the General Fusion reactor design is going to work. It will almost certainly achieve fusion (detect neutrons or excess heat) just like with sonoluminescence. Will it be over unity? Well.. I would wager more money on this design than any others that I’ve seen.
https://en.wikipedia.org/wiki/Bubble_fusion
The liquid metal is sort of like the moderator in fission, except in this case it just limits how much hydrogen can fuse by taking the place of the hydrogen in the center.
Also the Carnot efficiency of a liquid hydrogen heat engine would be terrible because it's so cold. It would also be difficult to contain it if it got too hot and turned to gas.
It looks like the compressibility of water is about 46.4 parts per million for every unit increase in pressure:
https://en.wikipedia.org/wiki/Liquid#Volume
And compressibility is roughly inversely proportional to density:
https://en.wikipedia.org/wiki/Compressibility#cite_note-4
Water is 4.6e-10 Pa^-1 and mercury is 3.7×10–11 Pa^-1 so I would guess that the compressibility of liquid lead is comparable to that of mercury.
If we temporarily ignore the compressibility of hydrogen in the center of the bubble, then to find the maximum pressure we'd need to integrate the compression from outside in, based on the kinetic energy of incoming atoms starting from a certain velocity and exerting pressure on the atoms beneath as they come to rest.
Something similar happens in a type II supernova when a large star runs out of fuel and no longer has the heat energy to hold itself up (think of the hot atoms in the core like the gas in a bubble). When the outer layers collapse inward, they form a fluid hammer where the pressure and temperature are so extreme that a large portion of the center of the star fuses all at once.
https://en.wikipedia.org/wiki/Type_II_supernova
I'm having trouble finding a simple formula for the maximum pressure of a collapsing fluid, but this simulation could probably tell us if the General Fusion reactor would actually work:
Turns out they dont have anything in common apart from the name.
[0] https://generalfusion.com/2014/07/from-the-archives-general-...
mev_per_fusion = 17.59e6
mev_per_j = 1.602e-19
pwr_thermal = 1.5e9
j_per_fusion = mev_per_fusion * mev_per_j
fusions_per_second = pwr_thermal/j_per_fusion
l_He_per_second = 22.4 * fusions_per_second / 6.02e23
l_per_ballon = 14.1
ballons_per_hr = (l_He_per_second * 60 * 60)/l_per_ballon
I am reliably informed that spitting out an He+2 and turning into something chemically other is not fission. Apparently those unstable nuclei that split this way actually had a He nucleus bouncing around in there, and it tunneled out "honestly".
It would be pretty neat if we made helium a renewable resource, even if it is slow.
Just distill it out of the atmosphere before it escapes into space - it'll be only a small order of magnitude more expensive than today's helium.
What you need with fusion is fundamentally new science, not just an idea to pound into shape. That's rather a taller order than a disruptive crowd-scale gig play in the power industry.
Oddly, I remember a UFO TV show describing the alien powerplant as relying on liquid metal in some way. No idea if that is meaningful.
ITER has been working on one implementation of magnetic confinement. It's an international effort, bringing to the battle the advantages of scale and disadvantages of multilateral bureaucracy.
Since ITER was formed in 2007 [1], the bleeding edge has advanced beyond Tokomaks. Advanced computational methods birthed the Wendelstein 7-X [2]. Improved superconducting magnets are compacting designs, reducing costs--and thus accessibility to start-ups--through mass reduction.
It's almost likely a start-up beats ITER. And that's fine! I don't know if any of these designs would be where they are if ITER hadn't been funded.
To take your example of Wendelstein 7-X, the only sources I can find give an expected Q factor of 0.1. JET was getting 0.75 ages ago. ITER will hopefully hit 10. While I'm excited about stellarators because they're very interesting to research, they probably won't be catching up to tokamaks any time soon.
As a layman, is it right to think that this would mean viable fusion has arrived at that point? I mean, 10x energy out/in is a victory, no? Is there another factor that stops ITER from being immediately used and replicated for energy generation?
Note, I am not talking about really long term radioactive waste here, more like things that are dangerous for less than 100 years. Still problematic, but not for millions of years like fission.
ITER will be first device to produce more heat energy than put in, but it won't be generating any electricity. [1] It will instead be used to make research on, so we can plan the next project, codenamed DEMO.
DEMO will produce net energy, but still be experimental, for designing final version of a commercial fusion power plant. And that commercial plant is aimed to be working by 2050. [2]
ITER is rather looked upon as risk-free and certain way to fusion, whereas startups... are startups. IMHO, we need both approaches.
Also there are many more fusion startups than General Fusion, here are some to follow:
- Tokamak Energy: https://www.youtube.com/channel/UCuSlFJbBUIj1zfJLRnGXSow - LPP Fusion: https://www.youtube.com/channel/UCiBditpj7sdROMYz02qoCMQ - TAE Technologies: https://www.youtube.com/channel/UC-LHpK7z8vjMq2-pt4wG4ug - Commonwealth Fusion Systems: https://cfs.energy - First Light Fusion: https://firstlightfusion.com
1: https://www.iter.org/proj/inafewlines 2: https://www.iter.org/mag/3/22
We could have built a fusion reactor in the 90’s simply scaling up JET, but the amount of power that would be produced was not worth the investment. For example we lack the tritium production to keep up with even a single 1GW fusion reactor let alone a large scale deployment. So, we need to be able to produce it or get by with mostly DD reactions.
That’s just one of thousands of issues being investigated.
Commonwealth Fusion also thinks they can move faster than ITER with a Tokamak reactor, by utilising new and better superconductors. I suppose the design of ITER was locked down before those became available in large quantities.
Maybe governments should. That’s doesn’t seem like a large amount of money in the scheme of things and I’d rather the tech not belong to a startup.
(Ironically it was so large that until it shaken up, the project nearly sank for the usual "megaproject drama" reasons)
http://www8.nationalacademies.org/onpinews/newsitem.aspx?Rec...
Just to put things in perspective. ITER budget is estimated ~$25B. Seeking to produce >500MW with a 12T magnetic field. Massive radius. Twice any previous tokamak size. Just look at the pictures ;)
JET budget was ~$5B total. And achieved 25MW with a 5T coil. But without actually "burning plasma" (Max Q < 1.0)
Princeton Plasma Physics Lab run by DoE budget is >$100M per annum. So this represents a significant challenge, and not just in fund raising.
The most promising space might be in the design of "mini-magnets"
https://nationalmaglab.org/news-events/news/lbc-project-worl...
Their approach addressed one of the big engineering problems facing fusion: have materials that can withstand the power/area across the surface of the reactor, and particularly stand up to neutron and energetic charged particle bombardment of the reactor structure.
Their first approach involved putting a plasmoid (spheromak, as I recall) in a cavity in a bath of liquid metal (lithium say), then launching a focused shock wave inward to compress the cavity and the plasma to very high density. There would be no solid reactor component exposed to the radiation from the plasma (a thick layer of liquid lithium would be interposed in all directions), and the peak pressure could be much higher than structural materials could withstand (because the compression and reaction would occur on time scale short compared to the time required for a sound wave to propagate across the liquid.)
But it turned out this approach was fatally flawed.
While they had trouble with confinement, the big problem is that to get that fast a reaction, very high density, and therefore very strong magnetic fields (magnetic pressure goes as magnetic field squared) would be required. Peak fields in their first approach would be as high as 700 T. But this would imply very large currents would be flowing in the liquid metal compressing the magnetized plasma. Beyond ~100 T, these current would be so strong that the surface of the metal would be vaporized, and non-conducting metal vapor would flow into and quench the plasma. Game over.
So, they've gone to a slow scheme. The implosion is now subsonic, and also there's a metal post running down the center of the chamber to increase stability. But this ruins the main attractive feature of their concept. That metal post will be subject to orders of magnitude higher average neutron flux than the walls of typical fusion concepts, and will also be crushed with magnetic pressure from 100 T magnetic fields. The engineering to make this work would be beyond heroic. The subsonic compression also means the entire reactor vessel will experience very high pressures, even if the rest of it is shielded from the radiation.
During testing I suppose things could go wrong, but they’d probably be barking up the wrong tree then.
Whats real, is that a lot of money is sloshing around in the hands of people who are more motivated to put it into this kind of venture, than before. Space sucked up some of it, but now space is proven to be a viable investment choice, higher risk money has to look somewhere else.
Renewable energies will probably survive for a while but eventually it'll be all fusion. In my opinion, the production of fusion energy will be so cheap that it would be more cost effective to just dump the energy, hence the spikes in power consumption can be compensated by running more reactors and dumping the excess.
To put it another way, the same argument you're making could be applied to (say) making computers from vacuum tubes, or balloons out of lead, or any of a myriad of approaches to solving problems that are losers regardless of effort expended. Why are we assuming fusion isn't also similarly a loser?
All that could be true, and fusion could still be hopelessly uncompetitive. The problem is the complexity, difficulty, and size of fusion reactors. Free fuel doesn't make up for that. All the long term beyond-fossil fuel competitors fusion has to beat are also only loosely constrained by fuel availability.
Fusion reactors might be complex and difficult to figure out, but once it has been figured out the free market will inevitably make it cheaper.
Fuel availability is indeed a problem, IIRC the uranium reserves will hold us out for another 200 years before running out. At current energy demands. So realistically more like 100 years. Coal and oil will inevitably run out too. Sun and Wind don't produce a lot of power compared to Fusion when considering the rare earths required for the components. Fusion is just a lot more efficient and energy rich.
Fuel availability is NOT a problem. There is no shortage of sunlight, or wind, or uranium (if used in breeder reactors, and why are fusion reactors, which are breeders, allowed but fission breeders are not?) The 200 year figure for uranium assumes a once-through cycle. In breeders, ores with 50-100x less uranium per unit mass of ore would be usable, because breeder get so much more energy out of each unit of uranium mined.
Oh, and please don't repeat the Rare Earth canard. Solar doesn't use rare earths, and wind doesn't have to. I think you're just repeating talking points you haven't bothered to understand.
It's probably not going to be that cheap, so it will instead replace all that fossil power.
Renewables are also quick to scale out, and low impact to decommission, so there's no loss in keeping on accelerating wind farm deployment.
Doesn't seem likely, though.
I'm pretty sure you already lost most people here that isn't a physicist.
You say that a ring collider would be useless as a fusion energy source. I've never heard of a proposal to use a ring collider to create fusion energy, they're for investigating particle physics.
So I'm left none the wiser - what am I missing?