Plenty of people have already explained why 99% of the ventures are plain scams.
Small nuclear fission reactors are much more practical and already exist. In the extremely unlikely scenario that such a small reactor actually blows up (pretty much impossible by design) it’s an explosion smaller than some traditional bombs and way smaller than Hiroshima. But the only realistic risk is efficient supply chain of fuel and disposal of nuclear waste- again there are risks here but they are outweighed by not polluting the atmosphere with co2. We should use a lot more nuclear energy now, until renewables are more reliable.
Renewables also use lots of rare earth metals and generally are resource intensive to build and most components have a pretty short lifespan so for now nuclear is the greener way to produce power.
It makes me wonder how small such systems could go. If you pack the fissile material just so then perhaps you could make the lifetime fairly short (not an RTG). Then could there be an optimal size which would both provide reasonable life while making it infeasible to stockpile enough to make a nuclear weapon?
I'm too lazy to even back-of-a-napkin calculation. Though it seems like you'd need either a way to highly compress the fissile material or a really good neutron reflector to reach any sorta criticality. Neither seem likely exist though.
Well we know that aqueous homogeneous reactors (AHRs) can be very small; we’ve operated them with < 1 meter diameter cores at powers of >5MWth before. A big plant with 380MWth was estimated to be an approximately 2.5m diameter cylinder and 5m long primary reactor and breeding/shielding blanket, power density ~16kWth/L. https://www.osti.gov/servlets/purl/4123899
Smallest AHRs were ~2 feet or so in diameter and put out ~5kWth, so it’s at least possible that you could deploy them buried in your backyard or something like that.
Lots of interesting fusion startups. This group is using a gun type design that reminds of the Fat Man atomic bomb [0]. Except here it's a fusion target hit by high speed slug causing is to rapidly compression and undergo fusion. The key things is that unlike the NIF they have a clear path to power extraction. In production they are planning to use a chamber with circular sheets of falling liquid lithium to capture the fusion neutrons then transfer the heat [1]. Breeding some tritium along the way.
Cool idea. Capital costs would certainly be lower than any of the magnetic confinement designs, if it works.
The power plant design they show has a 150MWe target power. Will be an interesting engineering challenge scaling it up and keeping all the finicky little parts and seals in the gun working when by design it's connected to a (small) nuclear explosion by a long pipe. If the timing is right you could have a heavy rotating shutter shielding the muzzle from the backblast.
They will, fortunately, not need to solve any of those problems, because there won't be any power plant. Instead, they will spend all the investors' money and then go do something else.
What's your take on Helion? They're acting exactly like every other scammer on the surface, but the more I dig the more I find evidence of thinking about things like how much quartz will evaporate and get into parts you don't want it to over 10 years. I can't see an overriding reason why it's immensely stupid like all the other schemes out there either.
For a while they were describing D-He3 as "aneutronic", (that reaction is, but a mixed D-He3 plasma will be producing D-D side reactions, which produce neutrons) and some of their promotional materials showed reactors in standard ISO shipping containers. (missing the concrete biological shield it would need) However, I just checked their site again to link to those mistakes, and they've been removed, which is nice. Their CEO also made some nonsense remarks about how Helion reactors would be deployed directly to end users like datacenters, which the NRC wouldn't like.
They're a lot like the other fusion startups in the current scene. They have a machine, about which they make various surprising claims, but keep almost all the specifications secret, since it's a privately held venture rather than a public government-funded experiment. It's not obvious incoherent nonsense like solar roadways from a couple years back. Maybe it will work, maybe it won't. Check back in 10 years.
The D-He3 reaction itself is aneutronic. Overall, Helion's reactor would produce only 6% of its energy as neutron radiation, compared to 80% for D-T reactors. For Helion that means they extract electricity directly from fast-moving charged particles instead of using a heat cycle. In practical terms that's often what people are thinking about what they refer to aneutronic fusion.
The NRC and their UK equivalent have already been moving towards lighter regulation for fusion reactors, and that's for D-T reactors. A reactor like Helion's could well be regulated more like medical devices than fission reactors.
I'd lump all the other fusion startups into the same category as incoherent nonsense like solar roadways as they all rely on recycling energy through a steam turbine (which is already prohibitive even if you had free heat) in order to power their rube goldberg machine and somehow that's supposed to be 100x cheaper than existing steam turbines when excluding the fuel.
I was wondering if there was some incoherent nonsense I'd missed.
Helion is the only fusion startup I know of that is not obviously a scam.
They count on D-D side reactions for neutrons to use breeding tritium, which decays over decades to the 3He they need. I don't see how that could produce enough. If not, their thing might still end up usable to power outer solar system space probes, using 3He decayed from the usual CANDU-produced tritium.
The Princeton FRC design is intended for spacecraft propulsion. I don't know if it is more or less practical.
They say they'll use pure lithium but I don't see how that can work. One lithium nucleus plus one neutron makes one tritium nucleus. If you lose any tritium at all, you run out after a while. Other fusion projects include lead or beryllium, which releases two neutrons after getting hit by one. That keeps their tritium breeding over unity.
On top of that, First Light says they'll use natural lithium without enriching it to lithium-6, which makes things even worse.
If they used 50% enriched 6Li/7Li, they would breed extra tritium. But there would be no point, because they would have no way to refine it out. They don't care, because they know there will never be an actual power plant. They will spend investors' money, have some fun, and move on.
> But there would be no point, because they would have no way to refine it out
Why not? I'm not a subject manner expert, but from my armchair it seems that refining one element from another is far more straightforward than refining one isotope from another as is done with Uranium.
I would expect that hydrogen and lithium should be able to be refined chemically, as both are very reactive elements. And even if mechanical refining is necessary, we have much industry experience with that: Uranium isotopes have been mechanically refined for almost a century. Furthermore, lithium and hydrogen are far more dissimilar than are U235 and U238 - lithium has six times the atomic weight of standard hydrogen and double the atomic weight of tritium.
Heavy water reactors have been producing tritium at scale for decades. India is talking about deploying a bunch of new PHWRs. They're recovering tritium from water, obviously. Would it be much harder to recover it from molten lithium? (Lithium hydride complexes?)
I guess literally anything can be "PPB concentration" if you don't care how many parts it is per billion.
A 1GW fusion reactor would consume about a ton of fuel per year.[1] That's about 600 kilograms of tritium. Over the course of the year a reactor with a positive breeding ratio will produce more than that.
The breeding blanket for ITER will be about 2000 tons[2] and ITER is designed to produce 500MW.[3]
This means that ITER will produce at least 300 kg tritium in 2000 tons of blanket, over the course of a year. Collect the tritium annually and you've got a concentration level of 150 parts per million, or 150,000 PPB.
Doesn't mean you have to do it every day. CFS ARC is a 270MW reactor. In a month it will consume 13.5kg tritium. Current world tritium supply is 20kg, though we could produce more from fission reactors if we really wanted to. 13.5kg out of 2000 tons is 7 parts per million, but with a breeding ratio over one, more than that would be produced. Tritium inventory to start up the ARC reactor is 100 grams.
I've asked before but didn't get an answer. If we can achieve stable fusion, what are the plans for getting the power out?
The guy in the article said you just do the same thing as coal or any other plant - generate steam. But we're talking about millions of degrees vs a couple thousand. Does it really scale that simply?
Plasma temperature is high but total heat is similar to other power plants. The atoms are moving fast but there aren't many of them. So basically, surround the plasma with a neutron-absorbing coolant and you're good. CFS uses molten FLiBe salt, and some others use a molten mix of lead and lithium. Then you run water pipes through that.
I'm just guessing, but I imagine if you have a way of maintaining something at a temperature of millions of degrees, there's always a way to transfer that heat to
some other thing. For example, by moving a gas past the very hot object, thus heating up the gas, and then moving the gas through a more conventional heat exchanger, where you generate steam for a steam turbine. Depending on the speed of the gas, it absorbs energy but isn't necessarily heated to the same temperature of millions of degrees, so it doesn't destroy the heat exchanger.
I think this is somewhat similar to how a fission reactor is used to drive a steam turbine in an ordinary nuclear (fission) power plant.
Deuterium-Tritium fusion produces a neutron each time. Neutrons are not charged and so escape magnetic containment slamming into the reactor wall, transferring heat to it.
This is how you get heat out, it's also how you breed more tritium from lithium.
This, like all fusion startups (except maybe one), is a scam.
That is to say, none of the investors will get any of their money back. If they are OK with that, fine. But probably most are not. You can think of it as a stupidity tax: enough money to invest was also enough to hire somebody to explain how they are throwing their money away. But they didn't.
One reason (of several) that it is a scam is that, to get the power out usefully, you need a thousand tons of "blanket" to absorb kinetic neutrons and turn them into heat. You need a high proportion of lithium in your blanket, so that the neutrons hitting it can breed the tritium you will need for fuel tomorrow.
But running a full-scale power plant all day will only breed a few grams of tritium, that you must somehow sift out of your thousand tons of "blanket", at parts-per-billion concentration. Nobody knows any way to do this. But without doing it, you have no fuel to use tomorrow.
Even if you could get enough tritium, those hot kinetic neutrons are blasting all of the physical structure of your reactor, weakening it, and also making it extremely radioactive. After a remarkably short time, you have to replace all the solid parts. But they are all fantastically radioactive, so you need robots to do it with. Those robots do not exist. The used-up parts are, anyway, not like regular nuke waste; they will mostly decay in a century or two, probably.
Until then, presuming you could scare up tritium fuel, you would have a thousand tons of super-hot "blanket" you need to run water through pipes in, to boil and drive a steam turbine. But steam turbines, too, need expensive periodic overhauls.
Meanwhile, solar panels and wind turbines are producing the cheapest power the world has ever known, today. No radioactivity, no tritium, no persnickety steam turbines. Just clean power.
So, nobody would buy your super-expensive fusion plant even if it worked, because it would cost so much to operate you would need to ask a lot more money for its output than anybody will pay.
But the people running the startup have no need to care about any of that. They have fun making big expensive experiments with your money, cater in expensive lunches, and drive Ferraris, because why not? When the money runs out, they go do something else.
There is no force on Earth powerful enough to make them give any of the money back.
Another big scam, BTW, is NRGV, "Energy Vault", traded on public markets at $2B cap last I checked. Apparently it is not considered fraud to collect investment money for things that cannot work.
The paper is about how to prevent production of tritium. It mentions breeding tritium, but not how to extract grams of it, every day and at negligible cost, from a thousand tons of lithium salt. So, my point stands.
Do futile jabs at renewables, which are being deployed at industrial scale as I write this, serve to make fusion startups less scammy?
Renewables will not replace fossil fuels to an acceptable degree without first solving energy storage. The question is "is industrial energy storage cheaper than fusion energy". Not such a clear answer when the order of magnitude of either of those is not established.
Do futile jabs at fusion, but also try to keep in mind the goal is legacy, not identity.
Any civil engineer can explain numerous storage alternatives to you. It is all centuries-old tech, excepting only novel battery chemistries and catalysts.
>Meanwhile, solar panels and wind turbines are producing the cheapest power the world has ever known, today. No radioactivity, no tritium, no persnickety steam turbines. Just clean power.
there is more than just thermal energy, but so far it all looks like steam generation. if more experimentation reveals the persistence of the fusion reaction during perturberance of magnetic flux, we may be able to couple into the field with static coils.
One thing I don’t understand about fusion is the mechanics of gain factors. If we can achieve a fusion reactor with a very small gain factor of say 1.01, is that sufficient to kick off an energy revolution, or do we need something more extreme like 10x or 100x?
I suppose it boils down to what the “saturation threshold” of nuclear reactors is, where you can’t pump more energy in without breaking the thing.
In any case, what are the benchmarks that engineers are shooting for?
So the assumption is that once you exceed 1 with some reactor architecture, you've more or less got it provided you can build a bigger containment vessel.
ITER is as large as it is because within reasonable magnetic field strengths, you still need a certain amount of distance to curve the charged particles back towards the centre - and probability means you have a distribution, some but not all will make it. Bigger vacuum vessel, the more particles you can loop back into your reactor.
So, if we can provably get over 1, and validate our plasma behaviour models, we can then derive the correct engineering equations to target a specific Q factor when building the production type reactors.
Yes. The ITER successor is DEMO which is larger and meant to be the production power plant design. The idea is ITER proves out the plasma control physics and scaling laws for fusion, so you can then build DEMO, get the predicted results and say "right, this is how a fusion plant looks". ITER will do Q=10 if we're right anyway, but the scaling laws are all volume based: the real trouble with fusion is that building gigantic vacuum vessels is very hard to do, but we're at the limits of magnets (unless MIT can get HTSCs working, but even then, you still benefit from volume).
Tokamaks scale with the square of plasma volume but the fourth power of magnetic field strength. The REBCO used by CFS should let them get ITER-level output from a reactor a tenth as large.
I like to show this graphic. Q>1 is in the "we don't know but we have a good idea" territory. Self-heating (burning) plasma is an untested regime. That will change soon.
Not too long, given scaling laws. In tokamaks for example, fusion output is proportional to the square of plasma volume, and the fourth power of magnetic field strength.
"There are three boxes we need to tick, in order to overcome this repulsion I mentioned before and get the nuclei very close. And this is not an easy feat. We need high temperature (think a hundred million degrees), high density (have a lot of these nuclei in a very small space), and keep the nuclei in that small space long enough for them to “react”. "
High temperatures are usually used because the nuclei must have a lot of force to counter that of the liked charged partner. The most obvious way to do this is with heating the plasma because individual particles, when they collide head on, can have the combined momentum to plow their way together.
But Philo T Farnsworth found a clever way to get them close with electrostatic forces. If it weren't for those darned wires.
With millions of degrees that plasma viciously expands. An even more incredible contraction force must be used to keep this together long enough for "interesting results". This is done with inertial confinement like the Hbomb or emulations of it. Magnetic confinement merely slows the expansion, but it must at some point touch the walls.
Actually, heat is not wanted. You only need to get the nuclei close enough that they quantum tunnel to each other to relieve their own stress in their environment. 2 Dueterons spread farther than helium3 does. Think of it like phase changes in condensed matter. Except we don't care at all about electrons, simply move them somewhere that the fuel ions wish to congregate at. Fortunately this can be a single point, as charges are concentrated on pointy things, as Faraday found in his experiments. The other side is full of the fuel ions. They don't have to be hot but warming them a little in an environment that is under 770 giga-pascals of pressure might be enough to moderate a nuclear combination process. It isn't hard to create two chambers in a crystal and make them undergo reductions or oxidations to free ions or electrons (tragically this happens with lithium ion batteries all the time). If they are surrounded in an environment that is very hard, very good dielectric strength, ions or electrons can be freed with no where to go. This is known as a meta-stable state and many crystal patterns exhibit this. The best dielectric known is diamond and it's also the hardest and has a ton of other helpful properties. If diamond couldn't do this, then nothing can. A mad genius with money and time would not have to go further than it to rule it out completely.
Say my fancy idea doesn't work, if colliding macro projectiles is something useful to the author have they tried something like levitating pyrolytic carbon and propelling it with laser ablation? It could be done in a loop if part of the magnet can de-energize fast enough to allow the tiny block of carbon to escape.
The plan they have seems very Wile E. Coyote to me but fun and cool. I hope they succeed.
By “fingers” do you mean “things which can apply precisely controlled forces to individual atoms”, or..?
If you have two atoms in a vacuum with one moving directly towards the other at a not very high speed, I’m pretty sure they don’t fuse.
There’s a repulsive force, right? Like, the (expectation of) potential energy goes up (up to a certain point) as the centers of their nuclei get closer together (after perhaps getting lower for a bit because maybe they form a bond or something)?
So, presumably the “fingers” would have to do enough work to get past this potential energy barrier? (Or at least, make it high enough up this barrier that the probability of tunneling through becomes non-negligible?)
I can believe that, yeah, that sounds likely enough. However, even if my fingers overall can easily exert the necessary force, it isn't clear to me that this should imply that any individual molecular bond between atoms in my fingers should be able to withstand the necessary force.
To me, it feels like it shouldn't be able to? (I say "feels" because I have not like, looked up any of the numbers about this or anything like that, and I could easily be wrong)
And, perhaps this could be the/a reason one might doubt that containing it in a diamond would work as an alternative to things like parts being brought together suddenly through precise collisions or using confinement from magnetic fields and such?
Though, of course, I'm not saying that doubting for that reason would probably lead to a correct conclusion. I wouldn't know much of anything about how one would achieve nuclear fusion, or how strong chemical bonds are, etc. .
I think the problem with trying to fuse two nuclei with your fingers is that the recoil from the reaction is really going to hurt. In a diamond this will destroy it. So it would seem like the only way it could work is if it were done as a burst. With a reasonable fraction of a coulomb of charge on each side rushing together and blocked by a thin layer of diamond, for a brief moment a lot of nuclei will be hopping on top of each other. If the ions and electrons are liberated instantly, immediately after there will be a high energy explosion. So shhh.. don't tell anyone like General Groves.
In nature, those "fingers" are more often than not hydrogen atoms, and the force acting on them is gravity. 10^30 kilograms of hydrogen, in a stack 600,000 kilometers tall, makes for high enough forces for the hydrogen to fuse.
