Wind Generators | Universe Today

Written by Jerry Coffey

A wind generator is a rotating machine which converts the kinetic energy of the wind into mechanical energy. If the mechanical energy is then converted to electricity, the machine is called a wind generator. Wind machines were used in Persia as early as 200 B.C. This type of machine was introduced to the Roman Empire by 250 A.D. However, the first practical windmills were built in Sistan, Iran, beginning in the 7th century. These were vertical axle windmills, which had long vertical driveshafts with rectangle shaped blades.

The first wind generator in the United States was built in Cleveland, Ohio by Charles F. Brush in 1888. By 1908 there were 72 wind-driven electric generators from 5 kW to 25 kW. The largest machines were on 24 m towers with four-bladed 23 m diameter rotors. Around the time of World War I, American windmill makers were producing 100,000 farm windmills each year, most for water-pumping. By the 1930s wind generators were common on farms, mostly in the United States where distribution systems had not yet been installed. In this period, high-tensile steel was cheap, and windmills were placed atop prefabricated open steel lattice towers. A forerunner of modern horizontal-axis wind generators was in service in the USSR by 1931. This was a 100 kW generator on a 30 m tower, connected to the local 6.3 kV distribution system. It was reported to have an annual capacity factor of 32 %, not much different from current wind generators.

Turbines used by wind farms for the commercial production of electric power are usually three-bladed and pointed into the wind by computer-controlled motors. These wind generators have high top speeds of up to six times the wind speed, high efficiency, and low torque ripple, which contribute to good reliability. The blades are usually colored light gray to blend in with the clouds and range in length from 20 to 40 meters or more. The tubular steel towers range from 60 to 90 meters tall. The blades rotate at 10-22 revolutions per minute. A gear box is commonly used to step up the speed of the generator, although designs may also use direct drive of an annular generator. Some models operate at constant speed, but more energy can be collected by variable-speed turbines which use a solid-state power converter to interface to the transmission system. All turbines are equipped with shut-down features to avoid damage at high wind speeds.

Modern wind generators are being used to supplement energy created by the burning of fossil fuel. While wind power does not account for a large portion of energy production at this time it is growing quickly and does account for a large percentage of green energy.

Here on Universe Today there is a good article on the need for green energies. Astronomy Cast offers an episode on the definition of what energy exactly is. I hope that both inspire you to do more research on your own!

Filed under: Astronomy

Tags: wind energy, wind generator, wind power, wind turbines, windmill