I had never thought too much about concepts such as "renewable" and "sustaining."  Then the other night I watched the film, "The Corporation" which is excellent if anyone hasn't seen it.  I was most impressed with Ray Anderson, founder of Interface which is one of the largest commercial carpet manufacturers.  He was surprised to learn how much of the earth's resources were spent to generate $1 of revenue for his company.  He has basically concluded that businesses will never operate on a self-sustaining basis (e.g., leaving no footprint) and the result is that we are like an airplane out of control, not feeling the effects but with knowledge that the ground is down there and there will be a crash.  He presented himself to me as the most enlightened CEO-type I've ever listened to.  If anything, he and his company are trying to make a start and if all companies could at least make a start, it migth go a long ways towards delaying the inevitable.  He talked about how we are not paying the proper price for the resources we consume.  For example, we pay $3 for a gallon of gas, but that doesn't reflect the cost of pollution.  We are in effect stealing the gas and leaving a big debt to future generations.  So to the effect that we can use solar energy in our homes is a good thing.  If only it were more prevalent and cheaper to install.  If ever there were a good role for government regulation, it would be to create a climate where alternative energy sources were encouraged at every stage in the value chain.  It's something I don't spend a lot of time thinking about because we are living in a fool's paradise, but if we don't start now, when?