Wind Energy: An Overview

Spinning turbines at one of the San Gorgonio Pass wind farms near Palm Springs, California. (Photo: Lee Celano / AFP-Getty Images)

Currently the world's fastest growing renewable power source, wind energy is the transformation of the wind's kinetic force into mechanical power through a turbine. The mechanical power can be used for such tasks as grinding grain or pumping water, or converted into electricity through a generator for use by homes and businesses.

"[Though] only about five countries in the world produce nearly three quarters of all the wind power, with the growth rate that we are seeing [wind power] is the fastest growing energy source in the world," according to Joseph Florence of the Earth Policy Institute in Washington. "A decade ago, wind energy stood at 5,000 megawatts so that 60,000 megawatts of installed capacity that we have today represents a twelve-fold increase over the last ten years," said Florence in a Radio NZ interview.

Wind farms are essentially a large-scale grouping of turbines, which can vary in number from one or two to hundreds of turbines and generate power from as low as 50 kilowatts to several hundred megawatts. The largest single wind farm in the U.S. at present is the Stateline Wind Energy Center, situated along the Oregon-Washington border. The center, with around 450 turbines, has a generating capacity of 300 megawatts or enough electricity to power around 72,000 homes.

The turbines work as a type of reverse fan, using the wind to make electricity instead of an electrical current to make wind. The wind turns the giant blades, which spins a shaft connected to a generator that makes electricity (see diagram). End users receive this electricity through the existing electrical grid.

Wind turbine configurations. (Photo: Courtesy of the American Wind Energy Association)

Wind energy has played an important part in humankind's history with the first known windmill dating back to 2000 B.C. to ancient Babylon. First used in Europe in the 12th century to mill grain, by 1840, England had around 10,000 windmills scattered across the country. Though ultimately superseded by more cost effective machinery during the Industrial Revolution, the windmill is still regarded as an important part of the world's cultural landscape.

In countries such as Australia, the use of wind energy on rural properties was common until the introduction of grid electricity in the 1950's. Considered by many an iconic symbol of Australian rural life, many wind driven water pumps are still in use in rural parts of the country.

The traditional "farm windmill" of the American West first appeared toward the end of the 19th century with the export of windmills becoming a major enterprise according to the Iowa Energy Center Web site.

"Until the diesel engine came along, many transcontinental rail routes in the U.S. depended on large multi-vane windmills to pump water for steam locomotives," said the center.

"In the 1930's and 1940's, hundreds of thousands of electricity producing wind turbines were built in the U.S. … These wind turbines typically provided electricity to farms beyond the reach of power lines and were used to charge storage batteries, operate radio receivers, and power a light bulb or two. By the early 1950's, however, the extension of the central power grid to nearly every American household, via the Rural Electrification Administration, eliminated the market for these machines."

Modern interest in wind energy had its origin following the OPEC oil embargo of 1973 when research in alternative energy grew in response to rising oil prices. However, it was not until the turn of the 20th century, with mounting evidence supporting scientific opinion that tied global warming to CO2 emissions caused by fossil fuels, that large-scale wind farming was seriously contemplated.

Accounting for 23 percent of the total electricity needs in Denmark, 4.3 percent in Germany, and around 8 percent in Spain, Europe is currently the largest producer of wind powered electricity with 72 percent of all power generated globally. However, with countries such as India and China becoming aware that their developing economies need to be driven by more than fossil fuels, many wind energy companies are looking to these countries as the future growth market for wind power.

Josh Bradshaw, spokesman for the Australian wind energy company Roaring Forties spoke to the Australian ABC of the potential of the Chinese market.

"They want to install 30,000 megawatts of wind over there, which is almost as much as Australia's entire capacity," he said.

With the cost of use to the consumer falling steadily, and its mitigating effect on climate change, wind energy's future as an energy source seems to be assured. Currently the most rapidly growing renewable energy in the world, wind energy proponents believe wind energy is capable of further increasing its percentage of the world's energy needs as countries look to utilize more environmentally friendly fuels.

"Wind has come of age," said Lester Brown, president of the Washington-based Earth Policy Institute. "And wind can now go toe-to-toe with any of the fossil fuels in competing for markets."

"I think if we want to make wind the centerpiece of a new energy economy, including powering cars and generating electricity, I think it has the potential to totally dominate the U.S. energy economy," he said.

According to a July 2006 report by the Australian Conservation Foundation, the world must reduce greenhouse emissions by 60 percent in order to avoid dangerous climate change. A transition to wind energy away from CO2 polluting fossil fuel sources such as coal and oil is seen by wind energy supporters as a crucial first step in beginning this process.

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