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A wind turbine is a device that converts the kinetic energy of wind into electrical energy.

As of 2024, hundreds of thousands of large turbines, in installations known as wind farms, were generating over 1,136 gigawatts of power, with 117 GW added each year. Wind turbines are an increasingly important source of intermittent renewable energy, and are used in many countries to lower energy costs and reduce reliance on fossil fuels. Wind turbines are manufactured in a wide range of sizes, with either horizontal or vertical axes, though horizontal is most common. Commercial power production horizontal-axis turbines usually have three blades, upwind of their towers. Wind turbines produce among the cheapest renewable energy, and are clean, emitting no greenhouse gases. The power produced varies with the wind, not with demand, so it is an unreliable source of energy unless energy storage is available.

The first electricity-generating wind turbine was installed by the Austrian Josef Friedländer at the Vienna International Electrical Exhibition in 1883. It was a Halladay wind turbine for driving a dynamo.

Wind turbines are classified by the wind speed they are designed for, from class I to class III, with A to C referring to the turbulence intensity of the wind.

Likewise, the conservation of energy requires the energy given to the turbine from incoming wind to be equal to that of the combination of the energy in the outgoing wind and the energy converted to electrical energy. Accordingly, Betz's law gives the maximal achievable extraction of wind power by a wind turbine, known as Betz's coefficient, as 16⁄27 (59.3%) of the rate at which the kinetic energy of the air arrives at the turbine. In general, more stable and constant weather conditions (most notably wind speed) result in an average of 15% greater efficiency than that of a wind turbine in unstable weather conditions, thus allowing up to a 7% increase in wind speed under stable conditions. The higher the wind turbine will be, the higher the wind velocity on average.

Large three-bladed horizontal-axis wind turbines (HAWT) with the blades upwind of the tower (i.e. blades facing the incoming wind) produce the overwhelming majority of wind power in the world today. Small turbines are pointed by a simple wind vane, while large turbines generally use a wind sensor coupled with a yaw system.

One advantage of this arrangement is that the turbine does not need to be pointed into the wind to be effective, which is an advantage on a site where the wind direction is highly variable. When a turbine is mounted on a rooftop the building generally redirects wind over the roof and this can double the wind speed at the turbine. If the height of a rooftop-mounted turbine tower is about half of the building height it is near the optimum for maximum wind energy and minimum wind turbulence. There are several subtypes of the vertical-axis design, including the Darrieus wind turbine, also known as an eggbeater turbine. A floating wind turbine is an offshore turbine supported by a floating platform.

Wind turbines convert wind energy to electrical energy for distribution. The rotor, which is approximately 20% of the wind turbine cost, includes the blades for converting wind energy to low-speed rotational energy.

Typically, the glass/epoxy composites for wind turbine blades contain up to 75% glass by weight.

For the wind turbine blades, while the material cost is much higher for hybrid glass/carbon fiber blades than all-glass fiber blades, labor costs can be lower.

However, for large wind farms, distances of about 15 rotor diameters should be more economical, taking into account typical wind turbine and land costs.

Wind turbine blades represent only a fraction of overall waste in the US, according to the wind-industry trade association, American Wind Energy Association.

David Spera (ed,) Wind Turbine Technology: Fundamental Concepts in Wind Turbine Engineering, Second Edition (2009), ASME Press, ISBN 978-0-7918-0260-1

Quick Facts

• The higher the wind turbine will be, the higher the wind velocity on average.
• The rotor, which is approximately 20% of the wind turbine cost, includes the blades for converting wind energy to low-speed rotational energy.
• Wind turbines convert wind energy to electrical energy for distribution.
• Wind turbines are an increasingly important source of intermittent renewable energy, and are used in many countries to lower energy costs and reduce reliance on fossil fuels.
• Accordingly, Betz's law gives the maximal achievable extraction of wind power by a wind turbine, known as Betz's coefficient, as 16⁄27 (59.3%) of the rate at which the kinetic energy of the air arrives at the turbine.

Source material: Wikipedia - "Wind turbine". Adapted and summarized for DiscoverScroll. Original contributors are credited through the linked Wikipedia article. Read original on Wikipedia. CC BY-SA 4.0. Changes were made from the original.