The propellers of wind turbines are rotated by the wind and activate a generator, which produces electricity. Wind turbines harness the power of air moving from a high pressure location to a low pressure location. The propellers on a wind turbine are aerodynamically shaped to rotate when wind passes through them.
Wind is caused by the sun unevenly heating the Earth. Warm air rises, and cold air moves into the low pressure area left behind. The wind is the movement of these air masses around one another.
Wind energy is not a new phenomenon. Humans have used wind power for centuries to grind grains, pump water and produce electricity. Windmills usually have propellers shaped similarly to airplane or helicopter propellers to maximize efficiency. However, vertical windmill designs, shaped similar to a helix, are also sometimes used.
These wind-capturing structures are slanted in such a way that wind passing through them causes them to rotate. The energy of the rotating turbine is converted into electricity by a special generator, then used to power homes, appliances and other electrical devices.
Wind power is harvested both on dry land and water. Massive wind farms exist in the United States, as well as along its shorelines. In fact, Iowa and South Dakota use wind energy for nearly 25 percent of their overall power consumption as of 2014.