THE ARTEMIS PROJECT
PRIVATE ENTERPRISE ON THE MOON
'''Lunar Helium-3 as an Energy Source,
in a nutshell'''
http://www.asi.org/adb/02/09/he3-intro.html
Some He3 is available on Earth. It is a by-product of the maintenance of nuclear weapons, which would supply us with about 300 kg of He3 and could continue to produce about 15 kg per year. The total supply in the U.S. strategic reserves of helium is about 29 kg, and another 187 kg is mixed up with the natural gas we have stored; these sources are not renewable at any significant rate.
In their 1988 paper, Kulcinski, et al. (see ref note below), estimate a total of 1,100,000 metric tonnes of He3 have been deposited by the solar wind in the lunar regolith. Since the regolith has been stirred up by collisions with meteorites, we'll probably find He3 down to depths of several meters.
The highest concentrations are in the lunar maria; about half the He3 is deposited in the 20% of the lunar surface covered by the maria.
To extract He3 from the lunar soil, we heat the dust to about 600 degrees C.
We get most of the other volatiles out at the same time, so we'll be heating up the rocks anyway. (To get the oxgyen out, we'll turn up the furnace to about 900 deg C and do some other nasty stuff; but that's a different story.)