A wind turbine is a rotating machine that transfers kinetic energy from the wind into mechanical energy. If the mechanical energy is used directly by machinery, such as for pumping water, cutting lumber or grinding stones, the machine is called a windmill. If the mechanical energy is instead converted to electricity, the machine may be called a wind turbine generator (WTG), wind power unit (WPU), wind energy converter (WEC), or aerogenerator.
Turning the generator
The wind turbine's blades are turned by the wind. This turns a shaft turning slowly, at about 10-20 rpm with a high torque. The shaft goes into a reduction gearbox with a ratio of about 1:50, although some wind turbine gearboxes can have a ratio of 1:100 or more. Some wind turbines may have no reduction gearbox at all, and have a ratio of 1:1. The gearbox turns the generator more quickly, at around 1000 rpm, at a low torque. The generator creates electricity. This electricity is combined with any other wind turbines that may be in the same wind farm. This combined electricity may be used locally, or adjusted to match the electricity in the power grid and sent to the power grid.
Although wind turbines are a renewable source of energy and don't pollute the environment as a result of generating power, they have an environmental impact. Some people think that wind turbines create a lot of noise and look unappealing. However, wind turbines are placed no closer than 300 meters from residential homes. At that distance, a wind turbine is no louder than an average household air conditioner.
Wind Turbine Media
Nashtifan wind turbines in Sistan, Iran
James Blyth's electricity-generating wind turbine, photographed in 1891
The first automatically operated wind turbine, built in Cleveland in 1887 by Charles F. Brush. It was 60 feet (18 m) tall, weighed 4 tons (3.6 metric tonnes) and powered a 12 kW generator.
Offshore Horizontal Axis Wind Turbines (HAWTs) at Scroby Sands Wind Farm, England
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- GeReports http://www.gereports.com/post/92442325225/how-loud-is-a-wind-turbine/ Archived 2017-04-06 at the Wayback Machine