4 ms·

I don't disagree with any of what you say but if Helion's approach works (and that's a huge if) it would generate electricity directly, without need for a steam

I don't disagree with any of what you say but if Helion's approach works (and that's a huge if) it would generate electricity directly, without need for a steam turbine or any of the associated plumbing. My understanding is that a big part of the cost for fission is the turbine etc.

hinkley 1y ago
And danger. Turbines are more powerful at high temps, and now you have hot liquids near your reactor. Or you use molten salt as a middleman so the potential steam explosions are a little farther from the reactor.
captain_coffee 1y ago
And how would you "generate electricity directly", specifically? Let's talk physics and engineering, not vague statements. How would that energy generated from nuclear fusion be transformed into electricity "directly"? By which process / series of processes?
- cyberax 1y ago
  > And how would you "generate electricity directly", specifically? Using a particle accelerator (decelerator?) in reverse. I'm an investor in Tri-Alpha Energy, and they have tested a direct converter with the claimed 90+% efficiency.
- Animats 1y ago
  See "Induction systems"[1] The concept was proposed in 1963, but nobody ever made it work. That's the plan. Magnetohydrodynamic generators [2] do work, but they have electrodes in the gas. That works for jet engine type MHD generators, but fusion plasma is too hot for any solid material. What they're trying to do is known physics but very hard engineering. They're also trying for aneutronic fusion, using helium-3. If the plant generates large volumes of neutrons, it chews up the first wall between the reaction and the outside. It also makes what it hits radioactive, so there's a waste problem. Aneutronic fusion uses reactions that (mostly) generate alphas and betas. This is, again, known physics but very hard engineering. If they can get a demo machine going which solves either problem, that would be a huge advance. So far, that does not seem to have happened. There are other startups in this space. It's probably the way commercial fusion power will eventually be done. Not via the tokamaks, like ITER. [1] https://en.wikipedia.org/wiki/Direct_energy_conversion https://en.wikipedia.org/wiki/Direct_energy_conversion [2] https://en.wikipedia.org/wiki/Magnetohydrodynamic_generator https://en.wikipedia.org/wiki/Magnetohydrodynamic_generator [3] https://spectrum.ieee.org/aneutronic-fusion https://spectrum.ieee.org/aneutronic-fusion
  - XorNot 1y ago
    > There are other startups in this space. It's probably the way commercial fusion power will eventually be done. Not via the tokamaks, like ITER. There is literally no evidence to suggest this: Helion are making big claims but as noted have shown little incremental progress on their machines. The balance of history says if it happens it'll come out of a large government funded project: that's how fission happened, and there's plain old fission startups too who also are yet to deliver anything and we know fission works.
    - pfdietz 1y ago
      There is plenty of evidence. This is your ignorance speaking here.
      - XorNot 1y ago
        I feel very comfortable saying in 5 years Helion won't have anything. Because HackerNews was soooo confident that a startup style skunkworks initiative would lead to over-unity fusion in 5 years[1]...in 2014. Then they were soooo confident that MIT was going to blow past ITER to over unity fusion[2] ... in 2020. It's 2025, and the latter project is still running but now predicting it'll finish it's big reactor post-2030. Helion are currently now reporting no new results, but claiming they'll hit net-energy in 2028 somehow despite little technical detail. After claiming they'll show net-energy fusion in 2024.[3] So there's my evidence. Where's your evidence? It should be noted that I'm not actually against private fusion research - more research is great. But the unfounded confidence with which HackerNews users make predictions of the obvious superiority and success of private industry in achieving fusion has a track record of "we still don't have fusion" despite company's dating back as early to early last decade when we're mid-2020s now. [1] https://news.ycombinator.com/item?id=8458339 https://news.ycombinator.com/item?id=8458339 [2] https://news.ycombinator.com/item?id=24629828 https://news.ycombinator.com/item?id=24629828 [3] https://en.wikipedia.org/wiki/Helion_Energy https://en.wikipedia.org/wiki/Helion_Energy
        pfdietz 1y ago
- thinkcontext 1y ago
  From their Wikipedia page > Energy is captured by direct energy conversion that uses the expansion of the plasma to induce a current in the magnetic compression- and acceleration – coils. Separately it translates high-energy fusion products, such as alpha particles directly into a voltage. 3He produced by D–D fusion carries 0.82 MeV of energy. Tritium byproducts carry 1.01 MeV, while the proton produces 3.02 MeV. > This approach eliminates the need for steam turbines, cooling towers, and their associated energy losses. According to the company, this process also allows the recovery of a significant part of the input energy at a round-trip efficiency of over 95%. https://en.m.wikipedia.org/wiki/Helion_Energy https://en.m.wikipedia.org/wiki/Helion_Energy
  - slashdave 1y ago
    Well, at least they know how to invest in good PR. I assume their building permit includes plans. Someone should look them up.
- WJW 1y ago
  https://en.wikipedia.org/wiki/Magnetohydrodynamic_generator https://en.wikipedia.org/wiki/Magnetohydrodynamic_generator is the gist of it. If you have enough conductive plasma then just moving it through a magnetic field generates a current. Applied to fusion power, you heat the plasma through the fusion reaction then divert part of the plasma through the MHD generator. Tbh, I very much doubt that this is a realistic path in the coming decade (but would love to be proven wrong). AFAIK no experimental reactor has yet generated any net electrical power at all, let alone with any big (ie dozens to hundreds of) MW MHD generators. Getting even one of these aspects working would be a major advance, let alone doing both at once.
- jcims 1y ago
  Conceptual overview: https://www.youtube.com/watch?v=HlNfP3iywvI https://www.youtube.com/watch?v=HlNfP3iywvI
- pfdietz 1y ago
  Their system can reversibly compress the plasma by energizing a coil. If the plasma acquires more energy in that time (by fusion producing energetic charged particles), the expansion stroke can return more energy to the capacitors than the compression consumed. It's the electromagnetic plasma equivalent of a reciprocating internal combustion engine.
  - spwa4 1y ago
    ... except for the fact that they're claiming 95%+ efficiency in an engine type nobody has ever seen running when actual existing reactors of that type can't seem to make it to 1%, and the two types of engine you can compare this (ICE, steam turbine) have SOTA efficiencies of 35% and 48%. This seems less than realistic. Then again, this is being done with private funds. So let them, and frankly, I really hope it works. Hell, if they wanted reasonable subsidy for this, I say give it to them.
    - pfdietz 1y ago
      They have been doing compression and reexpansion on plasmas for a long time. They are claiming high efficiency on energy recovery in these (non-fusion) plasmas. They can also do energy injection and recovery just by pulsing the coils around an empty vacuum chamber (or one filled with nonconductive gas). There's nothing that should be unbelievable about this claim, and to dispute it would be to assert that they are outright lying. For short timescales where do you expect the energy to be going, if not back to the capacitors? Inductive energy storage on short time scales should be very efficient. Both the coils used and the plasma itself have sufficiently low resistivity. I think the gating technology for this was the switches. The 1% figure you give there isn't for anything resembling this process, so I don't know why you brought it up except for reasons of obfuscation or your own confusion.
cornholio 1y ago
Sure, they aim to extract energy directly from the field, but the three breakeven points are still important. A significant part of the energy will be lost as x rays and neutrons, since their D-H3 fuel cycle is not aneutronic; they will also have significant D-D reactions that are required to breed Tritium which they capture and then let ti decay to Helium-3. Overall, when you look at the total complexity and energy balance of the full reactor + fueling cycle, maintaining vacuum, keeping superconducting magnets at cryogenic temperatures, tritium extraction etc. then generating an order of magnitude more energy than inserted still seems necessary to achieve engineering breakeven.
- pfdietz 1y ago
  In the cycle under question (two DD reactions per D3He reaction), 91% of the fusion energy goes into charged nuclei, not into neutrons. In steady state where T is being allowed to decay into 3He and there's just one DD reaction, the fraction of energy in charged nuclei is even higher. X-ray emission is strongly dependent on electron temperature. One of the important aspects of Helion's scheme is the electron temperature is much lower than the ion temperature. Not only does this greatly reduce x-ray emission, it reduces plasma pressure at a given ion temperature vs. a plasma where the ions and electrons are in thermal equilibrium, thereby increasing the ion density and fusion rate. The pulses in Helion's scheme end (and the plasma energy is recovered) before the electrons can heat up.

hinkley 1y ago

And danger. Turbines are more powerful at high temps, and now you have hot liquids near your reactor. Or you use molten salt as a middleman so the potential steam explosions are a little farther from the reactor.

captain_coffee 1y ago

And how would you "generate electricity directly", specifically? Let's talk physics and engineering, not vague statements. How would that energy generated from nuclear fusion be transformed into electricity "directly"? By which process / series of processes?

cyberax 1y ago
> And how would you "generate electricity directly", specifically? Using a particle accelerator (decelerator?) in reverse. I'm an investor in Tri-Alpha Energy, and they have tested a direct converter with the claimed 90+% efficiency.
Animats 1y ago
See "Induction systems"[1] The concept was proposed in 1963, but nobody ever made it work. That's the plan. Magnetohydrodynamic generators [2] do work, but they have electrodes in the gas. That works for jet engine type MHD generators, but fusion plasma is too hot for any solid material. What they're trying to do is known physics but very hard engineering. They're also trying for aneutronic fusion, using helium-3. If the plant generates large volumes of neutrons, it chews up the first wall between the reaction and the outside. It also makes what it hits radioactive, so there's a waste problem. Aneutronic fusion uses reactions that (mostly) generate alphas and betas. This is, again, known physics but very hard engineering. If they can get a demo machine going which solves either problem, that would be a huge advance. So far, that does not seem to have happened. There are other startups in this space. It's probably the way commercial fusion power will eventually be done. Not via the tokamaks, like ITER. [1] https://en.wikipedia.org/wiki/Direct_energy_conversion https://en.wikipedia.org/wiki/Direct_energy_conversion [2] https://en.wikipedia.org/wiki/Magnetohydrodynamic_generator https://en.wikipedia.org/wiki/Magnetohydrodynamic_generator [3] https://spectrum.ieee.org/aneutronic-fusion https://spectrum.ieee.org/aneutronic-fusion
- XorNot 1y ago
  > There are other startups in this space. It's probably the way commercial fusion power will eventually be done. Not via the tokamaks, like ITER. There is literally no evidence to suggest this: Helion are making big claims but as noted have shown little incremental progress on their machines. The balance of history says if it happens it'll come out of a large government funded project: that's how fission happened, and there's plain old fission startups too who also are yet to deliver anything and we know fission works.
  - pfdietz 1y ago
    There is plenty of evidence. This is your ignorance speaking here.
    - XorNot 1y ago
      I feel very comfortable saying in 5 years Helion won't have anything. Because HackerNews was soooo confident that a startup style skunkworks initiative would lead to over-unity fusion in 5 years[1]...in 2014. Then they were soooo confident that MIT was going to blow past ITER to over unity fusion[2] ... in 2020. It's 2025, and the latter project is still running but now predicting it'll finish it's big reactor post-2030. Helion are currently now reporting no new results, but claiming they'll hit net-energy in 2028 somehow despite little technical detail. After claiming they'll show net-energy fusion in 2024.[3] So there's my evidence. Where's your evidence? It should be noted that I'm not actually against private fusion research - more research is great. But the unfounded confidence with which HackerNews users make predictions of the obvious superiority and success of private industry in achieving fusion has a track record of "we still don't have fusion" despite company's dating back as early to early last decade when we're mid-2020s now. [1] https://news.ycombinator.com/item?id=8458339 https://news.ycombinator.com/item?id=8458339 [2] https://news.ycombinator.com/item?id=24629828 https://news.ycombinator.com/item?id=24629828 [3] https://en.wikipedia.org/wiki/Helion_Energy https://en.wikipedia.org/wiki/Helion_Energy
      - pfdietz 1y ago
thinkcontext 1y ago
From their Wikipedia page > Energy is captured by direct energy conversion that uses the expansion of the plasma to induce a current in the magnetic compression- and acceleration – coils. Separately it translates high-energy fusion products, such as alpha particles directly into a voltage. 3He produced by D–D fusion carries 0.82 MeV of energy. Tritium byproducts carry 1.01 MeV, while the proton produces 3.02 MeV. > This approach eliminates the need for steam turbines, cooling towers, and their associated energy losses. According to the company, this process also allows the recovery of a significant part of the input energy at a round-trip efficiency of over 95%. https://en.m.wikipedia.org/wiki/Helion_Energy https://en.m.wikipedia.org/wiki/Helion_Energy
- slashdave 1y ago
  Well, at least they know how to invest in good PR. I assume their building permit includes plans. Someone should look them up.
WJW 1y ago
https://en.wikipedia.org/wiki/Magnetohydrodynamic_generator https://en.wikipedia.org/wiki/Magnetohydrodynamic_generator is the gist of it. If you have enough conductive plasma then just moving it through a magnetic field generates a current. Applied to fusion power, you heat the plasma through the fusion reaction then divert part of the plasma through the MHD generator. Tbh, I very much doubt that this is a realistic path in the coming decade (but would love to be proven wrong). AFAIK no experimental reactor has yet generated any net electrical power at all, let alone with any big (ie dozens to hundreds of) MW MHD generators. Getting even one of these aspects working would be a major advance, let alone doing both at once.
jcims 1y ago
Conceptual overview: https://www.youtube.com/watch?v=HlNfP3iywvI https://www.youtube.com/watch?v=HlNfP3iywvI
pfdietz 1y ago
Their system can reversibly compress the plasma by energizing a coil. If the plasma acquires more energy in that time (by fusion producing energetic charged particles), the expansion stroke can return more energy to the capacitors than the compression consumed. It's the electromagnetic plasma equivalent of a reciprocating internal combustion engine.
- spwa4 1y ago
  ... except for the fact that they're claiming 95%+ efficiency in an engine type nobody has ever seen running when actual existing reactors of that type can't seem to make it to 1%, and the two types of engine you can compare this (ICE, steam turbine) have SOTA efficiencies of 35% and 48%. This seems less than realistic. Then again, this is being done with private funds. So let them, and frankly, I really hope it works. Hell, if they wanted reasonable subsidy for this, I say give it to them.
  - pfdietz 1y ago
    They have been doing compression and reexpansion on plasmas for a long time. They are claiming high efficiency on energy recovery in these (non-fusion) plasmas. They can also do energy injection and recovery just by pulsing the coils around an empty vacuum chamber (or one filled with nonconductive gas). There's nothing that should be unbelievable about this claim, and to dispute it would be to assert that they are outright lying. For short timescales where do you expect the energy to be going, if not back to the capacitors? Inductive energy storage on short time scales should be very efficient. Both the coils used and the plasma itself have sufficiently low resistivity. I think the gating technology for this was the switches. The 1% figure you give there isn't for anything resembling this process, so I don't know why you brought it up except for reasons of obfuscation or your own confusion.

cornholio 1y ago

Sure, they aim to extract energy directly from the field, but the three breakeven points are still important. A significant part of the energy will be lost as x rays and neutrons, since their D-H3 fuel cycle is not aneutronic; they will also have significant D-D reactions that are required to breed Tritium which they capture and then let ti decay to Helium-3. Overall, when you look at the total complexity and energy balance of the full reactor + fueling cycle, maintaining vacuum, keeping superconducting magnets at cryogenic temperatures, tritium extraction etc. then generating an order of magnitude more energy than inserted still seems necessary to achieve engineering breakeven.

pfdietz 1y ago
In the cycle under question (two DD reactions per D3He reaction), 91% of the fusion energy goes into charged nuclei, not into neutrons. In steady state where T is being allowed to decay into 3He and there's just one DD reaction, the fraction of energy in charged nuclei is even higher. X-ray emission is strongly dependent on electron temperature. One of the important aspects of Helion's scheme is the electron temperature is much lower than the ion temperature. Not only does this greatly reduce x-ray emission, it reduces plasma pressure at a given ion temperature vs. a plasma where the ions and electrons are in thermal equilibrium, thereby increasing the ion density and fusion rate. The pulses in Helion's scheme end (and the plasma energy is recovered) before the electrons can heat up.