Wind Power

Wind is the movement of air from an area of high pressure to an area of low pressure. In fact, wind exists because the sun unevenly heats the surface of the Earth. As hot air rises, cooler air moves in to fill the void. As long as the sun shines, the wind will blow. And as long as the wind blows, people will harness it to power their lives.

Ancient mariners used sails to capture the wind and explore the world. Farmers once used windmills to grind their grains and pump water. Today, more and more people are using wind turbines to wring electricity from the breeze.

Over the past decade, wind turbine use has increased at more than 25 percent a year. Still, it only provides a small fraction of the world's energy.

Facts About Wind Power!

Facts About Wind Power!

The biggest wind turbines generate enough electricity to supply about 600 U.S. homes. Wind farms have tens and sometimes hundreds of these turbines lined up together in particularly windy spots, like along a ridge. Smaller turbines erected in a backyard can produce enough electricity for a single home or small business

Wind is a clean source of renewable energy that produces no air or water pollution. And since the wind is free, operational costs are nearly zero once a turbine is erected. Mass production and

technology advances are making turbines cheaper, and many governments offer tax

incentives to spur wind-energy development.

Most wind energy comes from turbines that can be as tall as a 20-story building and have three 200-

foot-long (60-meter-long) blades. These contraptions look like giant airplane propellers on a stick. The

wind spins the blades, which turn a shaft connected to a generator that produces electricity. Other

turbines work the same way, but the turbine is on a vertical axis and the blades look like a giant egg

beater.

Some people think wind turbines

are ugly and complain about the noise the machines

make. The slowly rotating blades can

also kill birds and bats, but not

nearly as many as cars, power lines,

and high-rise buildings do. The

wind is also variable: If it's not

blowing, there's no electricity

generated.

Facts About Wind Power!

Nevertheless, the wind energy industry is booming. Globally, generation more than quadrupled between 2000 and 2006. At the end of last year, global capacity was more than 70,000 megawatts. In the energy-hungry United States, a single

megawatt is enough electricity to power about 250 homes.

Germany has the most installed wind energy capacity, followed by Spain, the United States, India, and Denmark. Development is also fast growing in France and

China.

Industry experts predict that if this pace of growth continues, by 2050 the answer to one third of the world's electricity needs will be found blowing in the

wind.

History of Wind Power!Humans have been using wind power for at least 5,500 years to propel sailboats and

sailing ships. Windmills have been used for irrigation pumping and for milling grain since the 7th century AD in what is now Afghanistan, Iran and Pakistan

In the United States, the development of the "water-pumping windmill" was the major factor in allowing the farming and ranching of vast areas otherwise devoid of readily accessible water. Wind pumps contributed to the expansion of rail transport systems throughout the world, by pumping water from water wells for the steam locomotives.

The multi-bladed wind turbine atop a lattice tower made of wood or steel was, for many years, a fixture of the landscape throughout rural America. When fitted with generators and battery banks, small wind machines provided electricity to isolated farms

The modern wind power industry began in 1979 with the serial production of wind turbines by Danish manufacturers Kuriant, Vestas, Nordtank, and Bonus. These early turbines were small by today's standards, with capacities of 20–30 kW each. Since then, they have increased greatly in size, with the Enercon E-126 capable of delivering up to 7 MW, while wind turbine production has expanded to many countries

Electricity Generation:Capacity Factor

Since wind speed is not constant, a wind farm's annual energy production is never as much as the sum of the generator nameplate ratings multiplied by

the total hours in a year. The ratio of actual productivity in a year to this theoretical maximum is

called the capacity factor. Typical capacity factors are 20–40%, with values at the upper end of the range in particularly favorable sites. For example, a

1 MW turbine with a capacity factor of 35% will not produce 8,760 MW·h in a year (1 × 24 × 365), but only 1 × 0.35 × 24 × 365 = 3,066 MW·h, averaging to 0.35 MW. Online data is available for some locations and the capacity factor

can be calculated from the yearly output. Unlike fueled generating plants, the capacity factor is limited by the

inherent properties of wind. Capacity factors of other types of power plant are based mostly on fuel cost, with a small amount of downtime for

maintenance. Nuclear plants have low incremental fuel cost, and so are run at full output and achieve a 90% capacity factor. Plants with higher fuel cost are throttled back to follow load. Gas turbine plants using natural gas as fuel

may be very expensive to operate and may be run only to meet peak power demand. A gas turbine plant may have an annual capacity factor of 5–25%

due to relatively high energy production cost