NRG Systems - How the Wind Creates Electricity

Perhaps the simplest way to describe how a wind turbine creates electricity is to say that it works just like a hydroelectric generator. At hydropower stations, falling or flowing water is used to spin the rotor of a turbine (a rotor that looks quite a bit like an everyday electric fan or an industrial cooling fan), and the turbine rotor drives the shaft of a generator to produce electricity.

Wind energy works in very similar fashion, especially similar to "run-of-the-river" hydro stations that make use of the flowing water in a river or stream. In the case of wind, of course, the "river" is an invisible one made of air, but the principle is the same. As the air flows past the rotor of a wind turbine (a rotor that looks a lot like an airplane propeller), the rotor spins and drives the shaft of an electric generator to produce electricity.

The air that drives the rotor is much less dense than water, and so the diameter of the rotor must be much larger than that of the rotor of a hydro turbine. A hydro turbine capable of generating one megawatt (MW) of power would be several feet in diameter—a 1-MW wind turbine's rotor would be roughly 175 feet across.

Wind turbines come in all sizes, from those with rotors measuring a few feet across (often used for battery charging on sailboats or vacation homes) to those with rotors hundreds of feet in diameter (used to generate "bulk" electricity that is fed into the utility transmission and distribution system).

Turbine subsystems include:

blades (rotor) that convert the wind's energy into rotational shaft energy;
a nacelle containing a drive train, usually including a gearbox* and a generator;
a tower, to support the rotor and drive train; and,
electronic equipment such as controls, electrical cables, ground support equipment, and interconnection equipment.

*Some turbines operate without a gearbox.

Substations collect the electricity produced by large-scale wind turbines and convert it to a higher voltage before sending it across wires. Transmission towers and lines deliver the electricity to a substation where it is converted to a lower voltage for use in homes or businesses.