Wind turbines have been employed by humans for various purposes for thousands of years, but the technology of today, used for generating electricity, is much more complicated than windmills. Wind turbines produce power when wind propels blades attached to a rotor connected to the main shaft that spins an electric generator. Wind turbines are large, complex structures, some as tall as 328 feet with blades 260 feet long, constructed of up to 8,000 parts.
Historically windmills were used to pump water and crush grain. Today the primary use of wind turbines is for energy. The higher the wind speed, the more electricity wind turbines produce, so energy companies construct turbines tall so the blades are higher in the atmosphere, where winds blows at greater speed.
The potential of wind turbines to produce energy in the United States is estimated at about 4,000 gigawatts of electricity, or about four times the capacity of the entire U.S. electric system. All of these wind resources won't be developed, but the potential illustrates how valuable the resource of wind can be to coastal cities. As of the end of 2014, wind power's 65.8-gigawatt capacity supplies electricity to more than 17.5 million homes in the United States. Wind power capacity has increased 25-fold since 2000. The use of wind power can help reduce greenhouse gas emissions that contribute to global warming and climate change.