3 ms·

This is true but misleading. It's wrong to think that the fusion process in the Sun is burning at any sort of physical limit. The Sun is a self-balancing equil

This is true but misleading. It's wrong to think that the fusion process in the Sun is burning at any sort of physical limit. The Sun is a self-balancing equilibrium. Gravity causes the matter to collapse, which increases heat and pressure at the core and causes matter to fuse, which releases energy that pushes matter away from the core. As such fusion only occurs at the rate needed to maintain this equilibrium, and that rate is less than you'd think intuitively. Not only that but our Sun is relatively small and weak. Type-O stars, for example, can have a luminosity a million times greater than our Sun's.

yaakov34 15y ago
My basic point is that the time scale and size scale of stars are so far, far outside human scales, that it's misleading to talk about a reactor somehow being like them, even if it uses fusion. It's really a completely different process. The comparison is used to put a gleam in the eyes of laymen, by making them think of "harnessing" something bright and limitless. You might as well talk about fission reactors harnessing the power of supernovas - it's kind of true (I think - I am not an astrophysicist), since supernovas produced heavy elements like uranium, and we are now using the energy that was stored in these atoms by the reactions in those stars. But it's misleading to use this fact in a policy article, since it has absolutely nothing to do with anything practical in relation to a fission reactor. My secondary point is that people do not have an intuitive understanding of these scales, which is why I used my "chicken soup" examples. I stand by that - I think that people hear "fusion" and do not understand how much unlike a star the reactor would be.
- teamonkey 15y ago
  Agreed, although there's degrees of accuracy. Since carbon was formed in stars you could also say that fossil fuel is harnessing the power of the stars. Fusion is the primary mechanism at the core of a star and would also be the primary mechanism in a fusion reactor, that does make it a partially valid comparison. (Supernovas use a different mechanism.) But let's not write off fusion over fission because the most common reactor in the solar system has a comparatively low energy output. It does kind of underemphasise the immense amount of energy that nuclear power generates per unit of fuel. It would take a few kilos of seawater to power a family for a year (a single person drinks tonnes of water each year). It should be very safe compared even to non-fission options. The output is relatively clean, especially compared to non-fission options. Excluding initial R&D costs, it should be more efficient than fission in therms of $/W.

yaakov34 15y ago

My basic point is that the time scale and size scale of stars are so far, far outside human scales, that it's misleading to talk about a reactor somehow being like them, even if it uses fusion. It's really a completely different process. The comparison is used to put a gleam in the eyes of laymen, by making them think of "harnessing" something bright and limitless. You might as well talk about fission reactors harnessing the power of supernovas - it's kind of true (I think - I am not an astrophysicist), since supernovas produced heavy elements like uranium, and we are now using the energy that was stored in these atoms by the reactions in those stars. But it's misleading to use this fact in a policy article, since it has absolutely nothing to do with anything practical in relation to a fission reactor. My secondary point is that people do not have an intuitive understanding of these scales, which is why I used my "chicken soup" examples. I stand by that - I think that people hear "fusion" and do not understand how much unlike a star the reactor would be.

teamonkey 15y ago
Agreed, although there's degrees of accuracy. Since carbon was formed in stars you could also say that fossil fuel is harnessing the power of the stars. Fusion is the primary mechanism at the core of a star and would also be the primary mechanism in a fusion reactor, that does make it a partially valid comparison. (Supernovas use a different mechanism.) But let's not write off fusion over fission because the most common reactor in the solar system has a comparatively low energy output. It does kind of underemphasise the immense amount of energy that nuclear power generates per unit of fuel. It would take a few kilos of seawater to power a family for a year (a single person drinks tonnes of water each year). It should be very safe compared even to non-fission options. The output is relatively clean, especially compared to non-fission options. Excluding initial R&D costs, it should be more efficient than fission in therms of $/W.