HELIUM-3

Helium-3 is a gas that is rare on Earth but has several niche applications. It has been used in nuclear safety and lung-MRI devices, but helium-free alternatives have already been implemented and will phase out He-3 in these sectors. Today’s best -performing quantum computer chips are cooled by dilution refrigerators that recycle He-3 in a closed loop, and this will likely be the major use case for the next several decades. Most fusion reactors would not switch to He-3 fuels until second or third generation designs much later in the century, if at all; deuterium–deuterium reactors run as He-3 breeders could become net suppliers rather than consumers.

The Moon contains a greater ratio of He-3 to regular He-4 than does Earth, but the absolute abundance of He-3 in lunar soil is low ( <100 parts per billion), requiring massive earthmoving equipment to harvest it with both high upfront CAPEX and high recurring costs. Lunar helium-3 production should be traded against producing more of it on Earth than we already do, which can be accomplished in existing nuclear facilities and with upgrades to existing helium plants. Helium-3 companies have made the case there will be a time window where lunar He-3 is competitive against terrestrial supplies, but this relies on a low-probability set of circumstances to come together.