4 ms·

Thanks. So it sounds like there isn't an economic advantage of fusion over fission, except indirectly through less political opposition.

mchusma 5y ago
Fusion definitely has long term economic advantages over fission. The fuel is the most plentiful in the universe and the energy released from fusion is much higher than fission. The chart here shows the energy difference pretty well: https://www.nuclear-power.com/nuclear-power/fission/nuclear-fission-vs-fusion/ https://www.nuclear-power.com/nuclear-power/fission/nuclear-... More fuel + more energy from fuel = superior for most uses long term. If we pull it off.
- duvenaud 5y ago
  Okay, but the other commenters are saying that fuel is around 6% of the cost of running a fission plant. Do you really think fuel availability will be a decisive factor in say, the next 60 years?
  - ncmncm 5y ago
    In a word, no. Fission is already not competitive, so a technology much more expensive to build and operate is even less so. In ten years, solar and wind will be even cheaper than today, and will be supplying most of our energy needs.
    - MagnumOpus 5y ago
      Fission is non-competitive only because governments don't want it to be. France's nuclear fleet built in the 60s/70s with more primitive tech has capital/operating costs of 7c/kWh, which is fairly similar to commercial solar or wind in France - and is the cheapest option once you double the cost of the latter to account for extra storage/smart grids/other intermittency handling. (Not every place is Southern California where there are no clouds and the sun shines all year. Solar is cheap in some places, but not at high latitudes.)
      - ncmncm 5y ago
        Fission is not competitive because of high operational expenses, very long construction, and very high capital commitment, none of which will follow plummeting solar/wind/storage costs. So it gets less competitive with each passing day. Wind does not confine itself to lower latitudes.
ncmncm 5y ago
Right, the current crop of Tokamak designs getting the lion's share of funding would cost much more than 10x, per watt out, than fission, and the reactors would cost that much more to build, besides. Since fission is uncompetitive, that kind of fusion is completely impractical. Such reactors would also quickly destroy themselves, so would have no opportunity to pay back the investment. The only hope for useful fusion is if work on existing designs turns out to be applicable to actually practical, aneutronic forms. Current spending on those is negligible.
- duvenaud 5y ago
  Thanks for actually answering my question! I guess no one wants to be a downer, but I'm pretty shocked that no one else in this thread, or that I've talked to about this issue, or anything I've read about fusion, has mentioned that current designs aren't on track to be remotely cost effective, which is what you seem to be saying.
  - ncmncm 5y ago
    Most people think the fusion idea is cool enough to be enthused over, and assume all the deep technical difficulties, beyond actual fusing itself, will evaporate, because that would be cool too. Consider that the majority of startup companies with apparently good ideas never get to market. People like to think the hardest problem they know of right now is all that matters, but often it is a boring problem that sinks the company. Maybe it is technically solvable, but costs enough to destroy the value proposition. So long as solar and wind costs are still falling fast, any prediction about the viability of competing tech is at best provisional. Solar and wind benefit from the opposite effect: there are known problems, but they have lots of known viable solutions that are just competing for which ones (plural) will end up cheapest, or have the most side benefits, or are easiest to deploy. It used to be that poor round-trip efficiency would sink a storage technology, but generation has become so cheap that losses matter less than other considerations. 50% loss? Build out more panels! Hydrogen still has awful efficiency, electrolysers and fuel cells need platinum-group metals, and liquid hydrogen needs really rigorous handling, but H2 is so useful that those don't matter. Efficiency and cost will only improve. Ammonia synthesis is similar: super-useful, but maybe easier to make starting with water. (There will be a lot of waste oxygen soon.) Iron-air batteries likewise have poor efficiency, and low discharge rate, but the material basis is very, very cheap. You can gang up thousands in parallel to get the rate you need, and stick lithium or lead cells on the front to handle load spikes. Useless for cars, fine for utilities. Liquifying air is very mature tech, so as the basis for a storage medium it's a safe bet. Storage capacity grows with cheap tankage. And, excess LN2 is valuable, so when your tanks are full you still have revenue. It turns out there are myriad elevated basins that would be perfect for pumped hydro storage, another very mature technology. Unlike hydro generation, you don't need a whole watershed and river valley, just hills with a dip. Even if fusion fizzles for utilities, the mostly-aneutronic sort might be perfect for outer solar system propulsion, where a completely different set of constraints apply. And, military deployments will often not be able to lay out much solar where they land. So, even though fission is, relative to solar, super-expensive, places can be found where nothing else will do.

mchusma 5y ago

Fusion definitely has long term economic advantages over fission. The fuel is the most plentiful in the universe and the energy released from fusion is much higher than fission. The chart here shows the energy difference pretty well: https://www.nuclear-power.com/nuclear-power/fission/nuclear-fission-vs-fusion/ https://www.nuclear-power.com/nuclear-power/fission/nuclear-... More fuel + more energy from fuel = superior for most uses long term. If we pull it off.

duvenaud 5y ago
Okay, but the other commenters are saying that fuel is around 6% of the cost of running a fission plant. Do you really think fuel availability will be a decisive factor in say, the next 60 years?
- ncmncm 5y ago
  In a word, no. Fission is already not competitive, so a technology much more expensive to build and operate is even less so. In ten years, solar and wind will be even cheaper than today, and will be supplying most of our energy needs.
  - MagnumOpus 5y ago
    Fission is non-competitive only because governments don't want it to be. France's nuclear fleet built in the 60s/70s with more primitive tech has capital/operating costs of 7c/kWh, which is fairly similar to commercial solar or wind in France - and is the cheapest option once you double the cost of the latter to account for extra storage/smart grids/other intermittency handling. (Not every place is Southern California where there are no clouds and the sun shines all year. Solar is cheap in some places, but not at high latitudes.)
    - ncmncm 5y ago
      Fission is not competitive because of high operational expenses, very long construction, and very high capital commitment, none of which will follow plummeting solar/wind/storage costs. So it gets less competitive with each passing day. Wind does not confine itself to lower latitudes.

ncmncm 5y ago

Right, the current crop of Tokamak designs getting the lion's share of funding would cost much more than 10x, per watt out, than fission, and the reactors would cost that much more to build, besides. Since fission is uncompetitive, that kind of fusion is completely impractical. Such reactors would also quickly destroy themselves, so would have no opportunity to pay back the investment. The only hope for useful fusion is if work on existing designs turns out to be applicable to actually practical, aneutronic forms. Current spending on those is negligible.

duvenaud 5y ago
Thanks for actually answering my question! I guess no one wants to be a downer, but I'm pretty shocked that no one else in this thread, or that I've talked to about this issue, or anything I've read about fusion, has mentioned that current designs aren't on track to be remotely cost effective, which is what you seem to be saying.
- ncmncm 5y ago
  Most people think the fusion idea is cool enough to be enthused over, and assume all the deep technical difficulties, beyond actual fusing itself, will evaporate, because that would be cool too. Consider that the majority of startup companies with apparently good ideas never get to market. People like to think the hardest problem they know of right now is all that matters, but often it is a boring problem that sinks the company. Maybe it is technically solvable, but costs enough to destroy the value proposition. So long as solar and wind costs are still falling fast, any prediction about the viability of competing tech is at best provisional. Solar and wind benefit from the opposite effect: there are known problems, but they have lots of known viable solutions that are just competing for which ones (plural) will end up cheapest, or have the most side benefits, or are easiest to deploy. It used to be that poor round-trip efficiency would sink a storage technology, but generation has become so cheap that losses matter less than other considerations. 50% loss? Build out more panels! Hydrogen still has awful efficiency, electrolysers and fuel cells need platinum-group metals, and liquid hydrogen needs really rigorous handling, but H2 is so useful that those don't matter. Efficiency and cost will only improve. Ammonia synthesis is similar: super-useful, but maybe easier to make starting with water. (There will be a lot of waste oxygen soon.) Iron-air batteries likewise have poor efficiency, and low discharge rate, but the material basis is very, very cheap. You can gang up thousands in parallel to get the rate you need, and stick lithium or lead cells on the front to handle load spikes. Useless for cars, fine for utilities. Liquifying air is very mature tech, so as the basis for a storage medium it's a safe bet. Storage capacity grows with cheap tankage. And, excess LN2 is valuable, so when your tanks are full you still have revenue. It turns out there are myriad elevated basins that would be perfect for pumped hydro storage, another very mature technology. Unlike hydro generation, you don't need a whole watershed and river valley, just hills with a dip. Even if fusion fizzles for utilities, the mostly-aneutronic sort might be perfect for outer solar system propulsion, where a completely different set of constraints apply. And, military deployments will often not be able to lay out much solar where they land. So, even though fission is, relative to solar, super-expensive, places can be found where nothing else will do.