Deuterium costs several thousand dollars/kilogram. But even though it is just one part in several thousand of the hydrogen in water, there's enough deuterium in

Deuterium costs several thousand dollars/kilogram. But even though it is just one part in several thousand of the hydrogen in water, there's enough deuterium in your morning shower to provide all your energy needs for a year.[1] Cost of deuterium is definitely insignificant. Helion's other fuel is helium-3 which they'll make themselves by fusing deuterium. So the helium-3 cost will directly depend on the capital cost of the reactor producing it. (This may be the same reactor, both generating electricity and breeding He3. Or they may use dedicated He3 breeders, and minimize the D-D reactions in the generators.) [1] https://dothemath.ucsd.edu/2012/01/nuclear-fusion/ https://dothemath.ucsd.edu/2012/01/nuclear-fusion/