What Is Wind?
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.
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.
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.
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.
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.