4 ms·

Is commercial ICF realistic though? Each shot needs a carefully prepared fuel pellet. To get commercial power they'd have to fire a shot per second or so. That

Is commercial ICF realistic though? Each shot needs a carefully prepared fuel pellet. To get commercial power they'd have to fire a shot per second or so. That seems like a really expensive manufacturing operation to keep it going.

acidburnNSA 4y ago
There is an incredible dichotomy that I learned about from David Deustch, which is that things are either: a) ruled out by the laws of physics, or b) possible. Commercial ICF is in the latter category as far as I can tell. In other words, maybe?
- magila 4y ago
  While obviously true, I think it's also useful to distinguish where items in category b fall on the spectrum from "this will be commercially viable with minor refinement" to "this is three orders of magnitude away from commercial viability and we don't even have a theoretical path to get there". AFAIK energy generation with ICF is much closer to the latter than the former.
  - panick21_ 4y ago
    Not sure I agree. Fusion solves non of the problem of fission actually has. - Will Capx be lower compared to a advanced fission plant. Almost certainty not. - Will Fusion plan be significantly cheaper to fuel. Almost certainty not, uranium and thorium are available in waste quantities. - Will it solve proliferation concerns? No, if you have a control of a fission reactors you have the potential to do all sorts of things. - Will it solve the nuclear waste issue. Maybe slightly but advanced fission can produce waste that need to be stored for around 300 years and that is not actually that difficult. And that is of course if you assume that the 100s of billions in investment required will not have be be paid back in any way. That is partly fair because fission didn't have to do that either, but there the investment is shared with nuclear weapons (for better or worse). So I would say its closer to the second suggestion. I don't see a theoretical path of how a fusion reactor can be built cheaper then a comparable fission reactor. But I'm not a expert on fission, I have heard of some fission that could be built very small but all actual real designs for suggestion of commercial fission I have seen do not fall into that category.
- sudosysgen 4y ago
  Flying cars are also into category b for what it's worth.
  - acidburnNSA 4y ago
    Truth. https://www.jetsonaero.com/ https://www.jetsonaero.com/
- throwawaymaths 4y ago
  The real world presents a trichotomy: b) is two things b1) possible and worth the cost b2) merely possible
- ajnin 4y ago
  I think a condition needs to be inserted between a) and b) : x) require preexisting conditions not present in the Universe, or
- grecy 4y ago
  In one of Elon's video interviews with The Everyday Astronaut where they are staggered at the sheer scale of Starship, the booster and the launch/landing system, Elon said "We're not violating and laws of physics here... there's no reason this won't work". Also: "Here at SpaceX we specialize in turning the impossible into just late".
- quickthrower2 4y ago
  (b) should be "not yet known to be impossible"
imglorp 4y ago
Not to mention a tritium shortage [1?] -- assuming this is D-T fusion -- which it seems is going to be hard to get in the first place let alone throw it into a generator. https://news.ycombinator.com/item?id=31451902 https://news.ycombinator.com/item?id=31451902
- vlovich123 4y ago
  I don’t know if it’s all fusion reactors but General Fusion breeds tritium by surrounding the plasma with moving liquid lithium which breeds tritium and helium and they send the tritium back in. Seems sustainable. I don’t know why their plan is to just vent helium given the shortage although I imagine that’s a second order problem they can solve later.
  - bcrl 4y ago
    Is there really enough lithium in the world to supply fusion reactors while also meeting the demand for its use in batteries over the next 1000 years? It will be interesting to see what the actual long term consequences are for building fusion reactors, as humans are notoriously bad at predicting what unforeseen circumstances arise from new technologies. Maybe the Belters will mine lithium from asteroids and send them back to earth in exchange for air and water...
    - pfdietz 4y ago
      Fusion uses 6Li, which is only a minor fraction of natural lithium. The 7Li (93% of the element) can be used in batteries just fine. At one point back in the 1960s some physicists were trying to make a neutron detector using lithium, and it wouldn't work. They eventually discovered the lithium they had purchased from a chemical supply company was nearly pure 7Li. It had been sold back into the chemical market from the waste stream of the government's lithium enrichment facility.
  - panick21_ 4y ago
    Thorium is something that is literally a waste product that falls out of refining of rare metals. And natural Uranium is also available in waste quantities. Without even trying we would have enough for the whole world. And then compare to that the very complex and expensive process of process of breeding tritium. How does that make any sense? Sure, fusion is about 3 order of magnitude denser, but fission is already incredibly dense. The increase density doesn't really benefit you in any practical way unless maybe if you are trying to do interstellar flight or something.

acidburnNSA 4y ago

There is an incredible dichotomy that I learned about from David Deustch, which is that things are either: a) ruled out by the laws of physics, or b) possible. Commercial ICF is in the latter category as far as I can tell. In other words, maybe?

magila 4y ago
While obviously true, I think it's also useful to distinguish where items in category b fall on the spectrum from "this will be commercially viable with minor refinement" to "this is three orders of magnitude away from commercial viability and we don't even have a theoretical path to get there". AFAIK energy generation with ICF is much closer to the latter than the former.
- panick21_ 4y ago
  Not sure I agree. Fusion solves non of the problem of fission actually has. - Will Capx be lower compared to a advanced fission plant. Almost certainty not. - Will Fusion plan be significantly cheaper to fuel. Almost certainty not, uranium and thorium are available in waste quantities. - Will it solve proliferation concerns? No, if you have a control of a fission reactors you have the potential to do all sorts of things. - Will it solve the nuclear waste issue. Maybe slightly but advanced fission can produce waste that need to be stored for around 300 years and that is not actually that difficult. And that is of course if you assume that the 100s of billions in investment required will not have be be paid back in any way. That is partly fair because fission didn't have to do that either, but there the investment is shared with nuclear weapons (for better or worse). So I would say its closer to the second suggestion. I don't see a theoretical path of how a fusion reactor can be built cheaper then a comparable fission reactor. But I'm not a expert on fission, I have heard of some fission that could be built very small but all actual real designs for suggestion of commercial fission I have seen do not fall into that category.
sudosysgen 4y ago
Flying cars are also into category b for what it's worth.
- acidburnNSA 4y ago
  Truth. https://www.jetsonaero.com/ https://www.jetsonaero.com/
throwawaymaths 4y ago
The real world presents a trichotomy: b) is two things b1) possible and worth the cost b2) merely possible
ajnin 4y ago
I think a condition needs to be inserted between a) and b) : x) require preexisting conditions not present in the Universe, or
grecy 4y ago
In one of Elon's video interviews with The Everyday Astronaut where they are staggered at the sheer scale of Starship, the booster and the launch/landing system, Elon said "We're not violating and laws of physics here... there's no reason this won't work". Also: "Here at SpaceX we specialize in turning the impossible into just late".
quickthrower2 4y ago
(b) should be "not yet known to be impossible"

imglorp 4y ago

Not to mention a tritium shortage [1?] -- assuming this is D-T fusion -- which it seems is going to be hard to get in the first place let alone throw it into a generator. https://news.ycombinator.com/item?id=31451902 https://news.ycombinator.com/item?id=31451902

vlovich123 4y ago
I don’t know if it’s all fusion reactors but General Fusion breeds tritium by surrounding the plasma with moving liquid lithium which breeds tritium and helium and they send the tritium back in. Seems sustainable. I don’t know why their plan is to just vent helium given the shortage although I imagine that’s a second order problem they can solve later.
- bcrl 4y ago
  Is there really enough lithium in the world to supply fusion reactors while also meeting the demand for its use in batteries over the next 1000 years? It will be interesting to see what the actual long term consequences are for building fusion reactors, as humans are notoriously bad at predicting what unforeseen circumstances arise from new technologies. Maybe the Belters will mine lithium from asteroids and send them back to earth in exchange for air and water...
  - pfdietz 4y ago
    Fusion uses 6Li, which is only a minor fraction of natural lithium. The 7Li (93% of the element) can be used in batteries just fine. At one point back in the 1960s some physicists were trying to make a neutron detector using lithium, and it wouldn't work. They eventually discovered the lithium they had purchased from a chemical supply company was nearly pure 7Li. It had been sold back into the chemical market from the waste stream of the government's lithium enrichment facility.
- panick21_ 4y ago
  Thorium is something that is literally a waste product that falls out of refining of rare metals. And natural Uranium is also available in waste quantities. Without even trying we would have enough for the whole world. And then compare to that the very complex and expensive process of process of breeding tritium. How does that make any sense? Sure, fusion is about 3 order of magnitude denser, but fission is already incredibly dense. The increase density doesn't really benefit you in any practical way unless maybe if you are trying to do interstellar flight or something.