A short video from the U.S. Department of Energy illustrates how the 130' long blades of wind turbines generate power.

Trying to build a better planet. Read more from this special report.

Shaped a little like the wings of an airplane, the blades only turn at about 18 revolutions per minute but use gears to increase the speed to 1,800 revolutions per minute. For more on wind energy, check out Alexis Madrigal's photo gallery about the eight biggest wind farms in the world, which also happen to be the biggest in the U.S.

For more information from the U.S. Department of Energy, visit http://energy.gov/.