Today, wind provides less than 1 percent of the nation's energy, though the federal government estimates it could provide upwards of 20 percent (1). Wind turbines use energy from the motion of the wind to make mechanical energy, which is then converted to electrical energy. This, in turn, is fed into the utility grid and distributed to customers. Because no combustion is involved in the process, harmful gases, pollution, and other damaging emissions are not produced.
How They Work
Wind turbines turn like propeller blades when air currents move around them. These currents are influenced by terrain, and bodies of water.
http://www.eren.doe.gov/power/consumer/ (see Flash animation)
Evolution of Wind Power
Computer-controlled to turn into the wind and maximize production (or out of the wind if it's too strong)
What Do Turbines Look Like?
(1) U.S. News & World Report, Nov. 12, 2001