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Cold, net-positive fusion. Current fusion reactors either require more power than they output or would run far too hot to be sustainable. While I too am hopefu

by cyphar 7y ago

Cold, net-positive fusion. Current fusion reactors either require more power than they output or would run far too hot to be sustainable. While I too am hopeful that humanity will be able to crack cold fusion in the next few hundred millennia, it should be noted that cold fusion is something which has simply not occurred in our universe before. Yes, fusion is the most commonly-occuring process in the universe, but all of it runs hot. It is possible that net-positive cold fusion might never come to pass and we'll have to go back to solar panels so we can exploit the output of already-existing hot fusion from the Sun.

tsimionescu 7y ago
Why would you need cold fusion? Simply net-positive energy output from a (hot) fusion reactor would do the trick. Of course, there is a risk there that we will hit some fundamental efficiency limitation that simply makes it not worth it. But st least it's not known to be a physical impossibility, like cold fusion is believed to be. In fact, more than cold fusion, I think there is a reason to hope for warm superconductors at some point in the future.
- cyphar 7y ago
  That depends on how hot we're talking. I'm not up-to-date on the latest hot fusion work (so I might very well be completely wrong here) but I'd have naively assumed that containment would be a significant limitation of having stable hot fusion reactors. Most research fusion reactors I've seen online only run for minutes at most -- and that's with net-negative fusion.
  - ben_w 7y ago
    From what I’ve been told, the runtime limit is mainly because they have a stringent and tiny limit on the lifetime radiation production of their reactors. These limits are not technological, they are because the reactors are research projects. I believe the main losses are plasma instabilities, rather than the energy cost of the containment. This is somewhat secondhand knowledge though, I merely used to hang out in a pub with someone who worked in this field.
  - vlovich123 7y ago
    https://www.thedrive.com/the-war-zone/29074/skunk-works-exotic-fusion-reactor-program-moves-forward-with-larger-more-powerful-design https://www.thedrive.com/the-war-zone/29074/skunk-works-exot... Basically there's lot of research into how to do containment that's far more efficient than Tokamak reactors that suffer from the problem you mention. A 100 years is a really long time to bet against given how the pace of our innovation is constantly increasing, let alone 3000 years. Keep in mind that thorium has 3x the capacity & we don't even have reactors to process that so even "regular" has a very long shelf-life. Uranium scarcity isn't a thing when compared with global warming & meets our energy needs drastically better than solar/wind & even hydro while having a much more compact ecological foot-print.

by cyphar 7y ago

tsimionescu 7y ago

Why would you need cold fusion? Simply net-positive energy output from a (hot) fusion reactor would do the trick. Of course, there is a risk there that we will hit some fundamental efficiency limitation that simply makes it not worth it. But st least it's not known to be a physical impossibility, like cold fusion is believed to be. In fact, more than cold fusion, I think there is a reason to hope for warm superconductors at some point in the future.

cyphar 7y ago
That depends on how hot we're talking. I'm not up-to-date on the latest hot fusion work (so I might very well be completely wrong here) but I'd have naively assumed that containment would be a significant limitation of having stable hot fusion reactors. Most research fusion reactors I've seen online only run for minutes at most -- and that's with net-negative fusion.
- ben_w 7y ago
  From what I’ve been told, the runtime limit is mainly because they have a stringent and tiny limit on the lifetime radiation production of their reactors. These limits are not technological, they are because the reactors are research projects. I believe the main losses are plasma instabilities, rather than the energy cost of the containment. This is somewhat secondhand knowledge though, I merely used to hang out in a pub with someone who worked in this field.
- vlovich123 7y ago
  https://www.thedrive.com/the-war-zone/29074/skunk-works-exotic-fusion-reactor-program-moves-forward-with-larger-more-powerful-design https://www.thedrive.com/the-war-zone/29074/skunk-works-exot... Basically there's lot of research into how to do containment that's far more efficient than Tokamak reactors that suffer from the problem you mention. A 100 years is a really long time to bet against given how the pace of our innovation is constantly increasing, let alone 3000 years. Keep in mind that thorium has 3x the capacity & we don't even have reactors to process that so even "regular" has a very long shelf-life. Uranium scarcity isn't a thing when compared with global warming & meets our energy needs drastically better than solar/wind & even hydro while having a much more compact ecological foot-print.