Wind turbines generate energy when their three long blades rotate in the wind, turning a generator to produce electricity. One large turbine generates enough energy for over 500 homes. The largest wind turbines are equal in size to a 20-story building, with blades that are nearly 200 feet long.
On windy days an area of low pressure builds up on one side of each blade. The blades are drawn towards the low pressure area, creating enough lift to overcome the drag of the wind on the opposite side of the blade. A typical wind turbine rotor turns at 18 revolutions per minute, a speed that increases to nearly 1,800 revolutions per minute by the time a system of gears transmits the motion to the turbine generator.
As of 2015, all the wind turbines around the world are capable of generating 70,000 megawatts of energy. That is enough energy to power over 17 million homes. Some people are hopeful that by 2050 one-third of the world's energy needs can be met by wind turbines. Offshore wind turbines are excellent sources of energy for coastal communities, while turbines on land provide energy for many rural towns.
While wind turbines provide clean, renewable energy, they are not without controversy. Some communities complain about the sight and sound of turbines located near their homes, and much research is still necessary to mitigate the bird and bat fatalities caused by turbines.