3He on the moon occurs in regolith at a concentration of maybe 10 ppb. At that concentration, simply heating the regolith to drive out the 3He uses more energy than the 3He would produce in fusion, unless extreme heat recycling can be achieved (and good luck transferring heat into/out of powders in vacuum.)
Even if it could be recovered, all the 3He on the entire moon might power the world for maybe 100 years.
Thanks, didn't realize the energy balance was so bad.
That strengthens the point I was trying to get at, which was that there's no reason to go to the moon for He3 when, if we can get net power from He3, we can just make it in a D-D reactor and gain energy in the process.
My favorite 3He source would be "Planet X", if it exists and is an Earth (or perhaps even Mars) size planet out far enough that the temperature at the exobase is low enough to retain 3He in its atmosphere. Sure, getting there would be difficult, but this scenario assumes we have D3He fusion, which we can handwave would get the miners out there in a reasonable amount of time.
It will take fundamental advances to get to p-11B fusion. A startup working today is anyway in no position to achieve such fundamental advances; that is more in the line of national laboratories, or would be if they were not fooling with ITER instead. Maybe some of the ITER work will be useful for other things.
For D-3He fusion to be useful, we have to hope that it will be economically viable to synthesize 3He, in the meantime. Arguably, we ought to be making and stockpiling tritium now so there will be enough 3He when we need it; but that might be too optimistic.
Even if it could be recovered, all the 3He on the entire moon might power the world for maybe 100 years.