How to Colonize an Asteroid
Geo-Thermal energy comes from the earth. Our earth has a core of molten rock, and in weaker spots in the earth's crust, this molten material can be quite close to the surface. When this happens, most people think of a volcano, but hot springs and geysers are common too. We can harness some of the energy in a select few of these locations very effectively, but this will not be an option in the asteroids as none of them are large enough to maintain a liquid core.