How to Colonize an Asteroid
Most of the energy which we use in our society is produced through the burning of fossil fuels, but this is actually one of the most inefficient ways to use solar energy.
Plants grow by removing carbon from the atmosphere and using it to build new cell walls, and they derive the energy for doing this through the process of photosynthesis, which is one of natures ways of storing solar power. Coal, oil, and gas are the result of millions of years of decayed plants pilling up and compacting themselves. If there is enough heat, they will "cook" themselves down. It took the energy of the sun for the plant to process the carbon, so you could look at plants as crude solar power cells. Burning fire wood would be one way to release the solar energy, or waiting a million years for it to turn to coal or oil would be another way - but both methods are horribly inefficient ways of utilizing solar power, and we release the stored carbon back into the atmosphere as carbon dioxide. The process of generating electricity at a coal fired power plant is only .0125% efficient at converting the original solar energy into electricity{R.38.26}. Carbon dioxide is a "greenhouse" gas which traps heat in our atmosphere and contributes to global warming. Another of the waste products is carbon monoxide - which is toxic to most of the life forms on this planet. Think about it - if some people have used automobile exhaust as a tool to commit suicide, then what are we doing to our planet when we drive down the road?
One advantage, in my opinion, to colonising an asteroid is the fact that the ecosystem involved is far too small to even allow the use of fossil fuels. With only 12 square miles of surface area, having a campfire more than once a year could cause a dangerous imbalance in the atmosphere - if you could even get away with doing it that often. (That's a little on the depressing side though - sitting by a campfire can be an enjoyable pastime).