James Hanson , heads the NASA Goddard Institute for Space Studies in New York City. Read a succinct article about the global warming problem. For this reason, I am widening the scope of my website to include sustainable power generation.

Here is a method of determining the investment Rate of Return on an investment in solar or wind power. You know the cost, including installation. In the case of solar panels, you will know the average amount of energy harvested, depending on the location. Combined with the cost of energy in your area, the kW-Hr can be converted to $/month. Also, in the case of solar panels, the output is guaranteed for 20 years. (The rate of output decay is -0.5 % / yr.) Knowing the initial cost, $'s generated, and the life of the panels in years, the rate of return can be calculated here. In the case of windpower, the life of the windmill would come from the manufacturer. I have heard that very large windmills have a life is 40 years.

Note on "Renewable" energy. Someone pointed out to me that the term "renewable" is a poor choice of words, in that a law of physics is, that energy can neither be created or destroyed. I googled the word, and got an explanation "an energy resource that is replaced rapidly by natural processes". OK. So the distinction compares the rate of usage to the rate of creation. Here is a chart showing the rates of discovery and production of fossel fuels superimposed, for fossel fuels. Scroll down to the bottom of the page, and look at the chart labeled "The Growing Gap". The world would not be in such an energy dilemma, if the rate of production had stayed low over time, instead of using up the supplies in 150 years. I have heard that, on average, each person in the US, has the equivalent of 50 slaves working for him.