Researchers and space enthusiasts see helium 3 as the perfect fuel source: extremely potent, nonpolluting, with virtually no radioactive by-product. Proponents claim it’s the fuel of the 21st century. The trouble is, hardly any of it is found on Earth. But there is plenty of it on the moon.
Society is straining to keep pace with energy demands, expected to increase eightfold by 2050 as the world population swells toward 12 billion. The moon just may be the answer.
"Helium 3 fusion energy may be the key to future space exploration and settlement," said Gerald Kulcinski, Director of the Fusion Technology Institute (FTI) at the University of Wisconsin at Madison.
Scientists estimate there are about 1 million tons of helium 3 on the moon, enough to power the world for thousands of years. The equivalent of a single space shuttle load or roughly 25 tons could supply the entire United States' energy needs for a year, according to Apollo17 astronaut and FTI researcher Harrison Schmitt.
First, yes there is 3He on the Moon. It's present at about the one part per billion level. You have to heat the soil to about 700 degrees C to drive off the 3He -- that several megawatts per ton of heating dirt. To be charitable, let's assume that you use focusing mirrors to capture "free" solar thermal radiation. You then have to collect it, isotopically separate the 3He, cyrogenically freeze it, store it, and transport it back to Earth.
But when you get it home, then what? We haven't achieved D-T fusion above breakeven yet, let alone D-3He fusion (which is about an order of magnitude more difficult). Commercial fusion power is like the end of the rainbow -- it's always "just around the corner." So, you're stuck with several tons of 3He, which I guess is useful to fill balloon animals with.
A much more proactical way to get energy from the Moon is to make solar panels on the surface using local materials and lay out solar arrays on the surface. Then, beam the electrical power back to Earth using microwaves of lasers. Basically, the Solar Power satellite idea, without the enormous launch costs associated with that concept.