In my area (upper midwest) there is a service through the power company that let's you specify that your power comes from only windpower. With Xcel energy it's called Windsource. How it works is that they know how much power they are expected to produce from the wind farms in the area and then they sell that quantity of power to people interested in a cleaner source. The power still comes from the plant down the street, I just pay more for it. You pledge in 100kWh blocks and my monthly usage is between 500 and 700 so to make sure I always am covered by Windsource, I pledged 1MWh. On my bill it works out as charged and debited for the fuel cost, and then charged for the difference between wind and coal produced power. In the end I only pay for what I used, and it's just an extra 8 to 10 dollars a month. I just like knowing I'm promoting cleaner power.