A wind turbine is a device that converts the kinetic energy of wind into electrical energy. Wind turbines are typically used in wind farms to generate electricity. A typical wind turbine consists of a rotor, blades, a nacelle (containing the generator), and a tower. The rotor is connected to the main shaft, which spins a generator to produce electricity.
Wind turbines can be classified according to their orientation (horizontal axis or vertical axis), the type of rotor used (upwind or downwind), and whether they use direct drive or gearbox technology. Horizontal-axis turbines are the most common type; they have two or three blades mounted on a horizontal shaft. Vertical-axis turbines have blades mounted on a vertical shaft; these are less common but have certain advantages in certain applications.
Upwind turbines rotate into the wind, while downwind machines rotate away from it. Direct-drive generators are attached directly to the rotor shaft, while gearbox-equipped machines use gears to increase rotational speed and thus power output.
Wind turbines extract energy from moving air masses (known as winds) by converting it into mechanical rotation energy, which is then converted into electricity by an electrical generator. The amount of electricity generated by a turbine depends on the machine’s size and efficiency as well as on local conditions such as wind speed and density. In general, larger machines operating at higher speeds under good conditions can generate more power than smaller ones operating at lower speeds under less favorable conditions.
The first commercial wind farm was built in 1981 in Denmark. Since then, many thousands of large utility-scale turbines have been installed around the world, with an installed capacity of almost 600 GW as of 2019