Wind power is converted to electricity by a wind turbine. In a typical modern large-scale wind turbine, the kinetic energy in the wind (the energy of moving air molecules) is converted to rotational motion by the rotor (a three-bladed assembly at the front of the wind turbine). The rotor turns a shaft which transfers the motion into the nacelle (the large housing at the top of a wind turbine tower). Inside the nacelle, the slowly rotating shaft enters a gearbox that greatly increases the rotational shaft speed. The output (high-speed) shaft is connected to a generator that converts the rotational movement into medium voltage electricity (a few hundred volts). The electricity flows down heavy electric cables inside the tower to a transformer that increases the voltage of the electric power to the distribution voltage (a few thousand volts). Higher voltage electricity flows more easily through electric lines, generating less heat and fewer point losses. The distribution-voltage power flows through the underground lines to a collection point where the power may be combined with other turbines. In many cases, the electricity is sent to nearby farms, residences and towns where it is used. Otherwise, the distribution-voltage power is sent to a substation where the voltage is increased dramatically to transmission-voltage power (a few hundred thousand volts) and sent through very tall transmission lines many miles to distant cities and factories.

Wind Turbines

Wind turbines come in a variety of sizes, depending upon the use of the electricity. A large, utility-scale turbine may have blades over 40 meters long,  mounted on towers 80 meters tall (one blade would extend half way down the tower), produce 1.8 megawatts of power (1800 kilowatts), supply enough electricity for 600 homes and cost over $1.5 million. Wind turbines designed to supply part of the electricity used by a home or businesses are much smaller and less costly. A residential - or farm-sized turbine - may have a rotor up to 15 meters (50 feet) in diameter mounted on a metal lattice tower up to 35 meters (120 feet) tall. These turbines may cost from as little as a few thousand dollars for very small units up to approximately $40,000 to $80,000.