As the specter of peak oil and energy depletion looms here on earth, eyes turn to the moon with hopes of mining helium-3 (He3), a gas that's plentiful on the lunar surface but extremely rare back here on terra firma. The element is considered by some scientists to be perfect for radiation-free nuclear fusion, a reaction that directly generates electricity from Helium-3.

Not so fast, warn opponents of the idea, calling He3 fusion feasible but nowhere near practical… yet. For example, there's already an experimental He3 reactor operating here on earth, but it needs 1 kilowatt of power to generate a mere 1 milliwatt of electricity. Some observers are saying it'll be five decades before such power generation is practical.

And then there's the problem of getting back to the moon, a trip that's on lots of spacefarers' wish lists, including NASA with its plans for a return to the moon by 2020 with a permanent base built by 2024. Getting raw materials from the moon back to Earth presents yet another obstacle. None of this is impossible, but any practical implementation of these plans looks like it's a few decades away at the earliest. — Charlie White

Technology Review, via Treehugger