Wind energy is essentially
a form of solar energy. The wind is created when heat from the sun heats up the ground and the air at lower elevations. This hot air then rises and expands and forces cooler air down. This air movement creates wind, which is then captured by the turbine blades much in the way a sail from a boat captures wind energy.
http://science.howstuffworks.com/wind-power2.htm good animation and picture Wind turbines can bring electricity to remote areas as well as to the general electrical grid by capturing
between 20 and 40 percent of the energy in the wind. There is some controversy over implementing wind turbines, however, with a number of NIMBY (Not In My BackYard) type arguments being made. Wind turbines can not always run at 100% and their output is not entirely predictable.
There are also concerns with noise levels and any negative impacts tall turbines may have on bat and bird populations.
Add truth about birds, sound and wind turbines Wind speed map at http://science.howstuffworks.com/wind-power6.htm The concerns about the lack of predictability of wind and the variable power output seem to not be concerns yet, however, as several European countries, including Spain, Germany, and Denmark already supply over 20 percent of their grids with energy from wind
without adverse effects on the reliability of the system. Several US utility studies confirm that a large amount of wind can be entered into the US energy grid
without impacting its reliability. The Battelle Pacific Northwest Laboratory, a U.S. Department of Energy science and technology lab, estimates that wind power is capable of supplying 20 percent of the United States' electricity based on wind resources alone. The American Wind Energy Association puts that number at a
theoretical 100 percent, although this may be unrealistic and would require some sort of long term energy storage mechanism. Wind energy is currently a viable technology competing with fossil fuels for price and with an energy payback period of only three to eight months, according the the American Wind Energy Association. This means that the amount of time for a wind turbine to produce all of the energy that went into its construction and installation is only
three to eight months.
(67) has good picture of the parts of a turbine and a cost /KWh history graph