http://www.blm.gov/wo/st/en/
prog/energy/wind_energy.html

Wind Power

Winds are generated by uneven heating of the earth's land and sea surfaces from the sun. An estimated 1% to 3% of energy from the Sun that hits the earth is converted into wind energy. Only a very small portion of these winds are close enough to the earth to be considered accessible. These accessible winds also have to be sufficiently strong and steady in order to be exploited for energy. The best areas of potential wind energy are near coastlines. The central areas of large land masses usually have relatively low potential with a large exception being North and South Dakota. This information is covered more in depth in the why section.

A simple animation of the way a wind turbine operates:

http://www1.eere.energy.gov/windandhydro/wind_animation.html

The basic operation of a wind turbine is that wind turns the blades, subsequently spinning a shaft, which connects to a generator which produces electricity. The electricity is next sent through transmission and distribution lines to a substation, then on to customers. The composition of a wind turbine is relatively basic also. It is described below:

http://www.powerhousekids.com/stellent2/groups/public/documents/pub/phk_ee_re_001502.hcsp

1. Blades - Wind blowing in the direction of the blades causes them to rotate from "lift", much like an airplane flies. Most turbines have either two or three blades.
2. Rotor - The rotor is the name for the blades and the hub collectively.
3. Pitch - The pitch is the turning of the blades out of the wind to protect the turbine. The pitch controls the rotor speed and protects it from winds that are too high or too low to produce electricity.
4. Brake - Stops the rotor in cases of emergency.
5. Low-Speed Shaft - The rotor turns the low-speed shaft at about 30 to 60 rotations per minute.
6. Gear Box - Gears connect the low-speed shaft to the high-speed shaft and increase the rotational speeds from about 30 to 60 rotations per minute (rpm) to about 1000 to 1800 rpm. The high-speed shaft is driven at a rate that is required by most generators to produce electricity.
7. Generator - Induction generator that produces AC 60 cycle electricity from the rotation of the high-speed shaft.
8. Controller - The controller controls the operating threshold of the wind turbine. Most wind turbines start rotation around 8 mph and stop at 55 mph. A wind stronger than 55 mph could damage the wind turbine.
9. Anemometer - Transmits the measured wind speed to the controller.
10. Wind Vane - Transmits measured wind direction to the yaw drive. The yaw drive orients the turbine with respect to the wind.
11. Nacelle - The housing of the gear that sits atop the tower and contains the gear box, low- and high-speed shafts, generator, controller, and brake.
12. High-Speed Shaft - Drives the generator and driven by the low-speed shaft.
13. Yaw Drive - The yaw drive forces the rotor to face into the wind for upwind turbines as the wind direction changes. The wind blows the rotor downwind so they are not required to have a yaw drive.
14. Yaw Motor - Powers the yaw drive.
15. Tower - Taller towers enable turbines to capture more energy and generate more electricity due to the fact that power changes with elevation. The amount of power gained through this height advance is in the physics section of this web site

The wind turns the blades, which spin a shaft, which connects to a generator and makes electricity. The electricity is sent through transmission and distribution lines to a substation, then on to homes, business and schools.