It's just half a percent of total energy consumption in the U.S., but wind power is the fastest growing renewable energy source out there -- in terms of usage and capacity.

Demand is so brisk that GE has sold out 100 percent of 2006 production and 80 percent of 2007. In fact, there's a building boom underway. Last year, wind power capacity soared 35 percent in the U.S. and the build this year is expected to be bigger.