Why mine Saturn for He-3
I am curious why anyone mines Saturn for He-3? D-He-3 fusion is more difficult than D-D fusion, which produces He-3 and T as byproducts (every gram of deuterium (D) fused creates 375 milligrams of helium-3 (He-3) and 375 milligrams of tritium (T)). Assuming a 40% efficiency of converting the thermal energy to electricity and a consumption of half of the electricity produced to sustain the reaction, each gram of D fused would produce around 7 MW-h of exportable electricity, meaning that it produces net electricity, helium-3, and tritium. Tritium can then be stored until it decays to helium-3 while the helium-3 and electricity are sold off.
Of course, you would need to burn 4,000 tons of deuterium per year to produce the 3,000 tons of helium-3 per year consumed in Transhuman Space (1,500 tons per year from direct production and 1,500 tons per year from tritium decay), but that would just mean an extra production of around 3 TW of electricity, which is less than 2% the system demand in Transhuman Space. While the existence of nearly 40,000 tons of tritium would be a security issue, it could be addressed by having a portion of a national military devoted to securing, transporting, and storing the tritium until it decays into helium-3.
So, why mine Saturn for helium-3? Is it that much cheaper than forging it in a reactor? A 10 GW D-D fusion power plant would produce 510 grams of helium-3 per hour (and 510 grams of tritium per hour), which could supply sufficient fuel to supply (directly or indirectly) a 75 GW D-He-3 fusion power planet, so I do not imagine that it is the price. Is it the security issues surrounding the production and storage of tritium? If so, how do they prevent the Duncanites from just using D-D fusion to achieve energy independence?
|