Making Wind Work

By Scott Gates

Wind energy has been used to improve quality of life for thousands of years. Rudimentary windmills were pumping water in Asia and grinding grain in the Middle East as early as 200 B.C.

Wind turbines were first used to generate electricity in Denmark as far back as 1890, and multi-bladed mills became a symbol of rural America in the early 1900s. With recent advances in technology, this driving force has been channeled by electric cooperatives and other utilities into electricity. Last year, enough wind was harnessed to power almost 10 million American homes (roughly 35,000 MW).

With help of tax credits and federal funding, wind power costs have dropped from 80 cents per kilowatt-hour (kWh) in 1980 to 8 cents per kWh in 2009. (In comparison, the cost for electricity from coal-fired power plants averages 3.6 cents per kWh; nuclear power roughly 2.1 cents per kWh; and natural gas, 7 cents per kWh.) As the generation becomes more affordable, wind power plants in some parts of the country—often called wind farms—are now as common as weather-beaten windmills of the past.

How to Harness Wind

Wind power follows a basic premise: if you can turn a generator, you can produce electricity. Turbines convert the natural energy of wind into mechanical energy by attaching giant, wind-catching blades to a generator. When wind blows through the blades, they spin and generate power.

Wind turbines come in a variety of forms. The most common are horizontal-axis varieties, which look like a large pinwheel or fan. These typically sport three blades, although some have two, facing into the wind. Some small turbines that can be erected in a backyard to produce less than 100 kW, while their larger cousins tower hundreds of feet over the horizon, capable of generating more than 3.5 MW of power.

Another configuration puts blades on a vertical-axis to resemble an eggbeater held upright. This less common variation, dubbed the Darrieus turbine after a French inventor, follows the same basic turbine principles.

The U.S. Department of Energy (DOE)’s Office of Energy Efficiency and Renewable Energy provides a step-by-step look at how wind turbines tap potential energy at www.eere.energy.gov/windandhydro/wind_how.html.

Pros and Cons

Some parts of America seem custom-fit for wind power. Over the last three years, two Alaska cooperatives―Kodiak Electric Association and Alaska Village Electric Cooperative―have been named Wind Cooperative of the Year, an award sponsored by DOE and the National Rural Electric Cooperative Association, the Arlington, Va.-based service organization representing the nation’s more than 900 consumer-owned, not-for-profit electric cooperatives, public power districts, and public utility districts.

The 2009 honoree, Kodiak Electric, uses wind to meet 9 percent of its power requirements. By harnessing wind when possible, the co-op plans to save more than 800,000 gallons of diesel fuel in 2010.

But wind doesn’t blow everywhere, and rarely does so around the clock. Even in areas with strong wind resources, an active wind turbine typically only generates 20 percent to 30 percent of its “capacity factor”—the total electricity it could generate operating around the clock. A 2010 National Renewable Energy Laboratory (NREL) survey found less than 1 percent of land in states like Alabama, Kentucky, and Georgia windy enough to achieve at least 30 percent capacity factor.

Because it’s temperamental, wind can’t be relied on as a steady source of energy. Instead, think of wind as a “fuel displacer,” allowing baseload power plants that rely on fossil fuels like coal and natural gas to burn less when wind blows.

Moving energy from a wind farm to homes also raises difficulties. Transmission infrastructure may not be available in areas where the wind blows best, and building new transmission lines takes time, money, and a lengthy governmental approval process. Before turbines go up, studies must be done to judge the wind’s variability in a given area. And although the sight of a tall, white wind tower may not be as intrusive as other types of power plants, environmental and economic impacts must be assessed. Will the turbine disrupt bird or bat migratory patterns? Will shipping routes be affected by an offshore wind farm?

Although great strides have been made in recent years and more wind turbines are built daily, making wind work as a reliable, affordable energy source will take time. To learn more about wind power’s potential, visit the American Wind Energy Association at http://www.awea.org/ or NREL’s wind section, www.nrel.gov/wind.

Sources: U.S. Department of Energy, American Wind Energy Association, National Renewable Energy Laboratory

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