form of energy conversion in which turbines convert the kinetic energy of wind into mechanical or electrical energy that can be used for power. Since wind power does not require the use of fossil fuels, it is considered a renewable energy source. Historically, wind power in the form of windmills has been used for centuries for such tasks as grinding grain and pumping water. Modern commercial wind turbines produce electricity by using rotational energy to drive a generator. They are made up of a blade or rotor and an enclosure called a nacelle that contains a drive train atop a tall tower. Large wind turbines (producing up to 1.8 megawatts of power) can have a blade length of over 40 metres (about 130 feet) and be placed on towers 80 metres (about 260 feet) tall. Smaller turbines can be used to provide power to individual homes. Wind farms are areas where a number of wind turbines are grouped together, providing a larger total energy source.
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