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This video gets posted lately every time anyone posts any fusion news lately. It's not a bad video, but I think the point everyone is trying to make is like, "w

This video gets posted lately every time anyone posts any fusion news lately. It's not a bad video, but I think the point everyone is trying to make is like, "we're not even close, we're orders of magnitude away!", and that's true, but I think maybe a bit misleading. Since fusion experiments began in earnest in the mid-20th century, we've improved in terms of Q by about four orders of magnitude, and the pace of improvement was pretty steady through about the mid-90s, when ITER started to suck all the air (funding) out of the room. Commercial viability is probably somewhere between Q=10 and Q=30, depending who you ask and what specific technology you're talking about, and the best we've done so far is around Q=0.7. So... four orders of magnitude so far, and between one and two still to go. And finally ITER has some competition that could get progress back on track. It's a big lift, but not, like, impossibly or unattainably large.

VaxWithSex 5y ago
As the video states.
ncmncm 5y ago
Q=10, for the Q in typical use, would have no chance of commercial viability. More precisely, it would have substantially less commercial viability than fission, which today lacks it. If we got to Q=1000, we would have viability that might match fission. Viability better than fission is not possible with hot-neutron fusion. Thus, hot-neutron fusion is a dead end. It might be that things learned chasing hot-neutron fusion will turn out to be useful for something else, such as aneutronic fusion. But work on aneutronic fusion, itself, would be overwhelmingly more useful. Very little work is being done on aneutronic fusion.
- danaris 5y ago
  ....but if I'm understanding the article, and comments here from others more knowledgeable than me, this development is, in fact, work being done on aneutronic fusion.
  - ncmncm 5y ago
    Yes, it amounts to much of the "little work".
- willis936 5y ago
  The triple product performance increase needed to go from Qplasma = 10 and infinity is the same as Qplasma = 1 and 10 for DT stellarators.
  - ncmncm 5y ago
    Qplasma = infinity just means that you have transferred the burden from just getting your plasma fusing reliably to the problem of converting the energy coming out into useful form. That second burden is one nobody has even started on. All indications are that it cannot match the economic value, even, of fission, at any Q.
    - willis936 5y ago
      260 GW electrical power is being generated from fission neutrons right now. The fact that a fusion test reactor hasn't done this yet is a flimsy point. A burning plasma test machine hasn't even been made. How would you propose blankets and shields be demonstrated if not in a burning plasma machine?
      - ncmncm 5y ago
        > 260 GW electrical power is being generated from fission neutrons right now. At enormous cost. Nobody even has a plan for a way to operate a fusion plant at anything close to matching fission's cost, and fission itself gets less economically competitive with each passing day. If a fusion plant could be operated competitively, surely running the same energy collection system wrapped around a fission pile would do just as well, and thus better than existing fission plants? Try it and see!
        willis936 5y ago
        This notion of cost is misguided. Fossil fuels are not charged for their externalities. Mankind collectively pays for it decades later. And what of renewables? We couldn't run our society on wind and solar while still feeding everyone with the land we have without displacing millions. Even if we did, the total effort (cost) to society to build and replace terra scale machine arrays would be incredible. Fission offers a much more dense path. But what of the proliferation and accident concerns? If you set aside quarterly profits just for a moment you might see a path for humanity to stay on its current industrial path if it takes its medicine and solves its energy crisis.
- apendleton 5y ago
  Fission lacks commercial viability in large measure due to extreme, overly burdensome regulatory regimes that require dramatic overbuilding for safety margins, high barriers to adopting potentially-cheaper but architecturally novel designs (basically anything other than pressurized water reactors), and years and years of capital-cost-incurring red tape to deal with compliance. I think on paper, you're right that fission ought to be more commercially viable than anything any of the fusion people will be able to achieve any time soon, but I think there's at least a chance that fusion technologies will manage to get themselves regulated in a way that makes the all-in costs of fusion projects much more manageable, even if the reactor itself is more expensive, less power-dense, etc. In an NRC roundtable discussion last week, there was discussion suggesting that much of the need for, say, handling tritium, could be regulated under existing, relatively lightweight regulatory structures already in place for things like nuclear medicine waste, and it seems like both the US and UK energy regulatory authorities are pretty interested in building streamlined regulatory structures that make fusion much more approachable than fission historically has been.
  - ncmncm 5y ago
    Nukes lack commercial viability because they lack commercial viability. Much of their cost overburden arises from corruption tax, a problem common to public works projects massively expensive enough to need buy-in from a wide range of stakeholders who then expect patronage, to be charged to extreme cost overruns and schedule slip. Since no nuke plant has ever been built with private money, and there is no realistic prospect of one ever being built with only private money, this overburden will be lifted only when corruption has been suppressed. Then we will still have the enormous, foreseeable decommissioning cost, the very high operating cost, and the astronomical liability subsidy always omitted from cost figures, but charged to the general public.
- pfdietz 5y ago
  > Q=10, for the Q in typical use, would have no chance of commercial viability. This statement is not necessarily universally true. In particular, if one can convert the fusion energy to electricity with high efficiency (i.e., not by an ordinary thermal cycle as would be needed for the neutron energy in a DT fusion reactor), and if one could also recover the input energy to the plasma with high efficiency, then it could be practical to have a much lower Q. Helion's scheme is like this. I understand they've demonstrated 95% recovery of plasma energy (no fusion occurring, just heating and compressing the plasma, then recovering that energy to capacitors), which is rather impressive. Their commercial 50 MW concept would have Q = 2. Helion is the fusion company I feel most positive about, for that and other interrelated reasons.

VaxWithSex 5y ago

As the video states.

ncmncm 5y ago

Q=10, for the Q in typical use, would have no chance of commercial viability. More precisely, it would have substantially less commercial viability than fission, which today lacks it. If we got to Q=1000, we would have viability that might match fission. Viability better than fission is not possible with hot-neutron fusion. Thus, hot-neutron fusion is a dead end. It might be that things learned chasing hot-neutron fusion will turn out to be useful for something else, such as aneutronic fusion. But work on aneutronic fusion, itself, would be overwhelmingly more useful. Very little work is being done on aneutronic fusion.

danaris 5y ago
....but if I'm understanding the article, and comments here from others more knowledgeable than me, this development is, in fact, work being done on aneutronic fusion.
- ncmncm 5y ago
  Yes, it amounts to much of the "little work".
willis936 5y ago
The triple product performance increase needed to go from Qplasma = 10 and infinity is the same as Qplasma = 1 and 10 for DT stellarators.
- ncmncm 5y ago
  Qplasma = infinity just means that you have transferred the burden from just getting your plasma fusing reliably to the problem of converting the energy coming out into useful form. That second burden is one nobody has even started on. All indications are that it cannot match the economic value, even, of fission, at any Q.
  - willis936 5y ago
    260 GW electrical power is being generated from fission neutrons right now. The fact that a fusion test reactor hasn't done this yet is a flimsy point. A burning plasma test machine hasn't even been made. How would you propose blankets and shields be demonstrated if not in a burning plasma machine?
    - ncmncm 5y ago
      > 260 GW electrical power is being generated from fission neutrons right now. At enormous cost. Nobody even has a plan for a way to operate a fusion plant at anything close to matching fission's cost, and fission itself gets less economically competitive with each passing day. If a fusion plant could be operated competitively, surely running the same energy collection system wrapped around a fission pile would do just as well, and thus better than existing fission plants? Try it and see!
      - willis936 5y ago
        This notion of cost is misguided. Fossil fuels are not charged for their externalities. Mankind collectively pays for it decades later. And what of renewables? We couldn't run our society on wind and solar while still feeding everyone with the land we have without displacing millions. Even if we did, the total effort (cost) to society to build and replace terra scale machine arrays would be incredible. Fission offers a much more dense path. But what of the proliferation and accident concerns? If you set aside quarterly profits just for a moment you might see a path for humanity to stay on its current industrial path if it takes its medicine and solves its energy crisis.
apendleton 5y ago
Fission lacks commercial viability in large measure due to extreme, overly burdensome regulatory regimes that require dramatic overbuilding for safety margins, high barriers to adopting potentially-cheaper but architecturally novel designs (basically anything other than pressurized water reactors), and years and years of capital-cost-incurring red tape to deal with compliance. I think on paper, you're right that fission ought to be more commercially viable than anything any of the fusion people will be able to achieve any time soon, but I think there's at least a chance that fusion technologies will manage to get themselves regulated in a way that makes the all-in costs of fusion projects much more manageable, even if the reactor itself is more expensive, less power-dense, etc. In an NRC roundtable discussion last week, there was discussion suggesting that much of the need for, say, handling tritium, could be regulated under existing, relatively lightweight regulatory structures already in place for things like nuclear medicine waste, and it seems like both the US and UK energy regulatory authorities are pretty interested in building streamlined regulatory structures that make fusion much more approachable than fission historically has been.
- ncmncm 5y ago
  Nukes lack commercial viability because they lack commercial viability. Much of their cost overburden arises from corruption tax, a problem common to public works projects massively expensive enough to need buy-in from a wide range of stakeholders who then expect patronage, to be charged to extreme cost overruns and schedule slip. Since no nuke plant has ever been built with private money, and there is no realistic prospect of one ever being built with only private money, this overburden will be lifted only when corruption has been suppressed. Then we will still have the enormous, foreseeable decommissioning cost, the very high operating cost, and the astronomical liability subsidy always omitted from cost figures, but charged to the general public.
pfdietz 5y ago
> Q=10, for the Q in typical use, would have no chance of commercial viability. This statement is not necessarily universally true. In particular, if one can convert the fusion energy to electricity with high efficiency (i.e., not by an ordinary thermal cycle as would be needed for the neutron energy in a DT fusion reactor), and if one could also recover the input energy to the plasma with high efficiency, then it could be practical to have a much lower Q. Helion's scheme is like this. I understand they've demonstrated 95% recovery of plasma energy (no fusion occurring, just heating and compressing the plasma, then recovering that energy to capacitors), which is rather impressive. Their commercial 50 MW concept would have Q = 2. Helion is the fusion company I feel most positive about, for that and other interrelated reasons.