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Wind turbine

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

EERE illust large turbine
EERE illust large turbine

This technology is a vital source of intermittent renewable energy. Many nations use it to lower energy costs and reduce their reliance on fossil fuels. One study suggests wind power has the lowest relative greenhouse gas emissions. It also shows the least water consumption and the most favorable social impacts compared to coal, gas, or geothermal sources. Today, hundreds of thousands of large turbines exist in installations called wind farms. These installations were generating over 1,136 gigawatts of power, with 117 GW being added every year.

Most commercial power production comes from horizontal-axis wind turbines (HAWT).

HAWT and VAWTs in operation medium
HAWT and VAWTs in operation medium

These machines have a main rotor shaft and an electrical generator at the top of a tower. The blades are usually positioned upwind of the tower. Most HAWTs feature three blades to capture the wind effectively. To make electricity, the wind must hit the blades and cause them to rotate. This rotation moves a shaft inside the nacelle, which is the housing at the top of the tower.

Badaia - Parque Eólico -BT- 01
Badaia - Parque Eólico -BT- 01

Most large turbines include a gearbox. The gearbox takes the slow rotation of the blades and turns it into a much quicker rotation. This faster speed is necessary to drive the electrical generator. The generator then converts that mechanical motion into electrical energy.

There are several other types of turbines, specifically vertical-axis wind turbines (VAWT). These rotate around a vertical shaft rather than a horizontal one. Different designs exist, such as the Darrieus turbine, which looks like an eggbeater. Another type is the Savonius turbine, which uses scoops and is suitable for ships or rooftops.

Twisted Savonius wind turbine in operation@60rpm
Twisted Savonius wind turbine in operation@60rpm

Other designs include the giromill with straight blades and even airborne turbines that use wings tethered to the ground. Some turbines are even mounted on floating platforms. While vertical designs are common for smaller uses, they generally produce less power than horizontal models.

Humans have harnessed wind for centuries. The windwheel of Hero of Alexandria is one of the first recorded instances of wind powering a machine.

Growing size of wind turbines
Growing size of wind turbines

Practical wind power plants first appeared in Sistan, Persia, during the 7th century. These were vertical-axle windmills with rectangular blades made of reed matting or cloth. They were used to grind grain or draw up water. In 1883, Josef Friedländer installed the first electricity-generating wind turbine in Vienna. He used a Halladay wind turbine to drive a dynamo. This setup fed electricity into batteries to power lamps and tools. Later, in 1941, the first megawatt-class turbine, the Smith–Putnam, was connected to a utility grid in Vermont.

Efficiency is a major focus for scientists and engineers. A German physicist named Albert Betz developed a rule known as Betz's law.

Albert Betz
Albert Betz

This law states that no turbine can capture more than 59.3% of the wind's kinetic energy. This limit exists because the air must keep moving past the turbine after it passes through. This maximum possible extraction is called the Betz coefficient. In 2001, commercial turbines were delivering about 75% to 80% of this theoretical Betz limit. Efficiency can change over time due to factors like dust or insect carcasses on the blades. These can alter the aerodynamic profile of the airfoil and reduce its effectiveness.

Turbine blades are engineered using specific materials to maximize performance. Most blades are made of glass fiber composites. Some advanced blades use carbon fiber because it is stiffer, stronger, and less dense than glass. The choice of location is also critical for efficiency. Wind velocity is often higher near the shore due to temperature differences between land and ocean.

Placing turbines on mountain ridges or using windbreaks can also increase wind velocity. Engineers classify turbines from Class I to Class III based on the wind speeds they are designed to handle.

Wind energy connects to many different systems and global issues. While wind is a clean energy source, it can have an environmental impact on wildlife. However, these impacts can be mitigated. The power produced depends on the wind rather than on human demand. This makes it an unreliable source unless energy storage, like batteries, is available. There is also discussion regarding the need for critical materials like neodymium, praseodymium, and dysprosium. Some worry about geopolitical competition for these elements, though many turbines do not use permanent magnets. Ultimately, wind power remains one of the cheapest and cleanest ways to generate electricity globally.

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🖼️ Images & Media (16)
File:Windmills D1-D4 (Thornton Bank).jpg
Windmills D1-D4 (Thornton Bank).jpg
File:Albert Betz.jpg
Albert Betz.jpg
File:HAWT and VAWTs in operation medium.gif
HAWT and VAWTs in operation medium.gif
File:Twisted Savonius wind turbine in operation@60rpm.gif
Twisted Savonius wind turbine in...
File:EERE illust large turbine.gif
EERE illust large turbine.gif
File:WKA spannglieder.jpg
WKA spannglieder.jpg
File:Badaia - Parque Eólico -BT- 01.jpg
Badaia - Parque Eólico -BT- 01.jpg
File:Growing size of wind turbines.png
Growing size of wind turbines.png
File:Turbine Blade Convoy Passing through Edenfield.jpg
Turbine Blade Convoy Passing through Edenfield.jpg
File:Nordex Jonesboro Plant 001.jpg
Nordex Jonesboro Plant 001.jpg
File:Lamma wind turbine.jpg
Lamma wind turbine.jpg
File:Bahrain World Trade Center from below.jpg
Bahrain World Trade Center from below.jpg

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