6 ms·

> And it would face the same showstoppingly bad volumetric power density as tokamaks, because of limits on that energy flow through the surface of the reactor.

> And it would face the same showstoppingly bad volumetric power density as tokamaks, because of limits on that energy flow through the surface of the reactor. I do think it is worth persevering though. The future of energy is Solar/Wind but Fusion should not be ignored. It is one of Nature's fundamental processes. Mastering fusion could turn out to be useful in ways we cannot possibly fathom at the moment right now.

GordonS 4y ago
I agree. If we were able to eventually miniaturise fusion reactors, they would be incredible for space flight. Back on Earth, if they could be made safe enough, maybe we could even use them to run container ships?
- sidkshatriya 4y ago
  With all the fast neutrons emanating from a fusion reactor (and the heavy confinement that it requires) I don't think a container ship would be a safe enough environment (threat of disaster at sea, constantly jostling which might affect plasma stability etc.). But yes, there is a potential for a lot of space applications and other things we haven't thought of yet.
  - ClumsyPilot 4y ago
    what kindof disaster could be relevant in this context? If the ship sinks, the minor radioctivity of a shutdown reactor will not be relevany Technically, container ships are enormous and can use ballast water for shielding. I can't judge the ecobomics ofcourse
    - sidkshatriya 4y ago
      Well fusion reactors are likely to cost a huge amount of money when they do become operational. No point having them sinking in a storm. Probably just safer to charge a huge battery and put it on a ship (if you don’t want to use fossil fuels). Avoids a lot of unfoseen commercial risk. Even though you could use water for shielding, the metal container and other things that hold the reactor would be highly radioactive and brittle due to continuous neutron bombardment. You wouldn’t want that to be lost at sea spewing radiation (even though the reactor itself would shutdown automatically).
      - GordonS 4y ago
        > Probably just safer to charge a huge battery and put it on a ship Large container ships burn through 16 tons of bunker oil per hour, and each journey can last up to 3 weeks - any idea what size of battery such a ship would need? I have no clue how to calculate that), but I'm guessing it would be completely impractical, even if we made huge strides in battery energy density.
        stormbrew 4y ago
        There seem to be efforts towards battery powered container ships out there[1], independently of any speculated use of nuclear power to charge them. Most likely they'd be battery banks in containers that get swapped out and charged at port using the same equipment as is used to load and unload cargo I believe. I remember reading that they would have more limited range and lower top speeds, but that this might not be as much of a problem as it seems because the current routes are built around large container + long haul but that's not necessarily required (for all shipping at least). [1] eg. https://maritime-executive.com/editorials/could-battery-powered-container-ships-serve-transatlantic-trade https://maritime-executive.com/editorials/could-battery-powe...
        ClumsyPilot 4y ago
        here fuels like hydrogen might make sence, but why not 'normal' nuclear? There are hundreds of nuclear powered ships already - submarines, Icebreakers, carriers, etc.
        hollerith 4y ago
        >There are hundreds of nuclear powered ships already - submarines, Icebreakers, carriers, etc. Aren't they all operated by militaries though? So if a conspiracy of crew members tries to steal some enriched fuel or fission products, it is legal to just shoot them or throw them in jail for decade for trying.
        ClumsyPilot 4y ago
- pfdietz 4y ago
  DT fusion would be just ridiculous for space flight. Anything a DT reactor could do a fission reactor could do much better -- much smaller, much higher power density, much less complexity. And similarly for use in ships down here on Earth. In practice, synfuels would be better than either for ships on Earth.
  - dmichulke 4y ago
    Isn't the main reason for us not having fission rockets the fact that we don't want to have radioactive material explode a few kms above our head aka a dirty bomb?
    - pfdietz 4y ago
      A DT fusion reactor would have a thrust/weight ratio much less than 1, so it could not be used in a launch vehicle. It would be purely for use up in space. So, none of this "a few kms above our heads" nonsense.
      - deleted 4y ago
        [deleted]
  - GordonS 4y ago
    I don't understand this; if fission reactors were "better", we wouldn't be pouring so much into fusion? Also, if it makes a difference, I didn't mean we'd be bolting a first gen tokamak to a container ship; I meant, much later down the line, if we were able to miniaturise (similar to how we have nuclear powered subs and ice breakers).
    - pfdietz 4y ago
      You seem to think that government decisions are rational. Fusion is a meme technology. People just have this assumption that's it's valuable, without having rationally arrived at that conclusion (which, when you examine it in detail, is very difficult to justify.) I suspect this was because it started back in the 1950s when consent was easier to manufacture and nuclear was being pushed. Fission lost that glamour with most people, but fusion somehow has retained it.
Galaxeblaffer 4y ago
We already have the perfect way to create heat and the science around it has been long solved and understood. Solar and wind won't save us and fusion certainly won't. It amazes me how solar and wind dreamers all seem to like fusion but fission is just super evil.
- pfdietz 4y ago
  Why won't solar and wind save us? There are many bogus reasons people give for that (IMO incorrect) opinion; I'm wondering which one you're going to come up with.
  - Galaxeblaffer 4y ago
    I'm not coming up with anything, but the first and glaring problem is that we can't store the energy created in any meaningful capacity. Sure we have some ideas like power2x but that doesn't really help for grid scale storage covering periods of several days where no power is created due to the weather. So imo the biggest problem is that it's just not a reliable source of energy. Here in Denmark we've spent billions on wind and we have nothing to show for it our energy is almost as dirty as when we started and the biggest reason for that is that we now use gas and biomass instead of coal. I could go on, but what it all comes down to is that we already have the perfect source of energy with nuclear fission, we can easily connect it to existing grids and it even works for district heating further decreasing our reliance on gas and fossil fuels.
    - pfdietz 4y ago
      Ok, the "can't store energy" canard. No, we can, in multiple ways. Batteries of many different flavors, pumped hydro, storing as thermal energy (via resistive heaters or heat pump cycles), hydrogen (electrolyzers have crashed in price) and other e-fuels. Costs of these are declining rapidly as demand picks up and the scent of trillion dollar markets entices a wide range of enterprises and investors. Storage has not been much of a thing before because we were still burning fossil fuels and could just turn those up and down instead. But that doesn't mean storage wouldn't work. In Denmark now e-fuels will be much cheaper than the fossil fuels (well, except maybe coal) you are now using. You're temporarily stuck in a rough spot right now, but the way out is via renewables + storage, and you'll be saving money doing it.

GordonS 4y ago

I agree. If we were able to eventually miniaturise fusion reactors, they would be incredible for space flight. Back on Earth, if they could be made safe enough, maybe we could even use them to run container ships?

sidkshatriya 4y ago
With all the fast neutrons emanating from a fusion reactor (and the heavy confinement that it requires) I don't think a container ship would be a safe enough environment (threat of disaster at sea, constantly jostling which might affect plasma stability etc.). But yes, there is a potential for a lot of space applications and other things we haven't thought of yet.
- ClumsyPilot 4y ago
  what kindof disaster could be relevant in this context? If the ship sinks, the minor radioctivity of a shutdown reactor will not be relevany Technically, container ships are enormous and can use ballast water for shielding. I can't judge the ecobomics ofcourse
  - sidkshatriya 4y ago
    Well fusion reactors are likely to cost a huge amount of money when they do become operational. No point having them sinking in a storm. Probably just safer to charge a huge battery and put it on a ship (if you don’t want to use fossil fuels). Avoids a lot of unfoseen commercial risk. Even though you could use water for shielding, the metal container and other things that hold the reactor would be highly radioactive and brittle due to continuous neutron bombardment. You wouldn’t want that to be lost at sea spewing radiation (even though the reactor itself would shutdown automatically).
    - GordonS 4y ago
      > Probably just safer to charge a huge battery and put it on a ship Large container ships burn through 16 tons of bunker oil per hour, and each journey can last up to 3 weeks - any idea what size of battery such a ship would need? I have no clue how to calculate that), but I'm guessing it would be completely impractical, even if we made huge strides in battery energy density.
      - stormbrew 4y ago
        There seem to be efforts towards battery powered container ships out there[1], independently of any speculated use of nuclear power to charge them. Most likely they'd be battery banks in containers that get swapped out and charged at port using the same equipment as is used to load and unload cargo I believe. I remember reading that they would have more limited range and lower top speeds, but that this might not be as much of a problem as it seems because the current routes are built around large container + long haul but that's not necessarily required (for all shipping at least). [1] eg. https://maritime-executive.com/editorials/could-battery-powered-container-ships-serve-transatlantic-trade https://maritime-executive.com/editorials/could-battery-powe...
      - ClumsyPilot 4y ago
        here fuels like hydrogen might make sence, but why not 'normal' nuclear? There are hundreds of nuclear powered ships already - submarines, Icebreakers, carriers, etc.
        hollerith 4y ago
        >There are hundreds of nuclear powered ships already - submarines, Icebreakers, carriers, etc. Aren't they all operated by militaries though? So if a conspiracy of crew members tries to steal some enriched fuel or fission products, it is legal to just shoot them or throw them in jail for decade for trying.
        ClumsyPilot 4y ago
pfdietz 4y ago
DT fusion would be just ridiculous for space flight. Anything a DT reactor could do a fission reactor could do much better -- much smaller, much higher power density, much less complexity. And similarly for use in ships down here on Earth. In practice, synfuels would be better than either for ships on Earth.
- dmichulke 4y ago
  Isn't the main reason for us not having fission rockets the fact that we don't want to have radioactive material explode a few kms above our head aka a dirty bomb?
  - pfdietz 4y ago
    A DT fusion reactor would have a thrust/weight ratio much less than 1, so it could not be used in a launch vehicle. It would be purely for use up in space. So, none of this "a few kms above our heads" nonsense.
    - deleted 4y ago
      [deleted]
- GordonS 4y ago
  I don't understand this; if fission reactors were "better", we wouldn't be pouring so much into fusion? Also, if it makes a difference, I didn't mean we'd be bolting a first gen tokamak to a container ship; I meant, much later down the line, if we were able to miniaturise (similar to how we have nuclear powered subs and ice breakers).
  - pfdietz 4y ago
    You seem to think that government decisions are rational. Fusion is a meme technology. People just have this assumption that's it's valuable, without having rationally arrived at that conclusion (which, when you examine it in detail, is very difficult to justify.) I suspect this was because it started back in the 1950s when consent was easier to manufacture and nuclear was being pushed. Fission lost that glamour with most people, but fusion somehow has retained it.

Galaxeblaffer 4y ago

We already have the perfect way to create heat and the science around it has been long solved and understood. Solar and wind won't save us and fusion certainly won't. It amazes me how solar and wind dreamers all seem to like fusion but fission is just super evil.

pfdietz 4y ago
Why won't solar and wind save us? There are many bogus reasons people give for that (IMO incorrect) opinion; I'm wondering which one you're going to come up with.
- Galaxeblaffer 4y ago
  I'm not coming up with anything, but the first and glaring problem is that we can't store the energy created in any meaningful capacity. Sure we have some ideas like power2x but that doesn't really help for grid scale storage covering periods of several days where no power is created due to the weather. So imo the biggest problem is that it's just not a reliable source of energy. Here in Denmark we've spent billions on wind and we have nothing to show for it our energy is almost as dirty as when we started and the biggest reason for that is that we now use gas and biomass instead of coal. I could go on, but what it all comes down to is that we already have the perfect source of energy with nuclear fission, we can easily connect it to existing grids and it even works for district heating further decreasing our reliance on gas and fossil fuels.
  - pfdietz 4y ago
    Ok, the "can't store energy" canard. No, we can, in multiple ways. Batteries of many different flavors, pumped hydro, storing as thermal energy (via resistive heaters or heat pump cycles), hydrogen (electrolyzers have crashed in price) and other e-fuels. Costs of these are declining rapidly as demand picks up and the scent of trillion dollar markets entices a wide range of enterprises and investors. Storage has not been much of a thing before because we were still burning fossil fuels and could just turn those up and down instead. But that doesn't mean storage wouldn't work. In Denmark now e-fuels will be much cheaper than the fossil fuels (well, except maybe coal) you are now using. You're temporarily stuck in a rough spot right now, but the way out is via renewables + storage, and you'll be saving money doing it.