Wind Power PDF

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Wind Power

Whispering Willow Wind Farm Franklin County, IA

Using the wind to create electricity has been around for a long time, you've probably seen windmills on farms. When the wind turns the blades of a windmill, it spins a turbine inside a small generator to produce electricity, just like a big coal power plant.

A windmill on a farm can make only a small amount of electricity, enough to power a few farm machines. To make enough electricity to serve lots of people, power companies build "wind farms" with dozens wind turbines.

Wind farms are built in flat, open areas where the wind blows at least 14 miles per hour.

Iowa ranks 2nd in the nation for wind energy production as there are almost 2,900 utility scale wind turbines in Iowa.  This creates enough electricity to power 1,000,000 homes. Minnesota is fourth in the nation for wind energy production and Wisconsin is 19th.

They sure are big!

When it comes to size, bigger is better. The bigger the wind turbine, the more wind it reaches and the more electricity it produces.

Wind turbines used for large-scale wind farms come in various sizes, but are usually approximately 13 feet wide at the base, and between 230 and 265 feet tall at the hub. With one of the blades in the upright position, the total height is approximately 406 feet, like the one pictured here at Cedar Ridge Wind Farm in Fond du Lac County, Wisconsin.

When it comes to size, bigger is better - the bigger the wind turbine, the more wind it reaches and the more electricity it produces.

How many wind turbines do you need to have a wind farm?

Wind farms can have as few as five wind turbines or as many as 150. One of the largest wind farms in the U.S. is in Altamont Pass, California. It has more than 4,800 wind turbines. Visit the Encyclopedia of Earth for more information on Altamont Pass wind farm.

Alliant Energy owns and operates three wind farms in Iowa, Minnesota, and Wisconsin:

• Bent Tree Wind Farm in Freeborn County, Minnesota (pictured at right)
• Cedar Ridge Wind Farm in Fond du Lac County, Wisconsin
• Whispering Willow Wind Farm in Franklin County, Iowa

In addition to the wind farms owned by Alliant Energy, we also purchase more than 400 MW of energy from other wind farms throughout our service territory

How a wind turbine works

A wind turbine works the opposite of a fan. Instead of using electricity to make wind, a turbine uses wind to make electricity.

The wind turns the blades, which spin a shaft, which connects to a generator and makes electricity. The electricity is sent through transmission and distribution lines to a substation, then on to homes, business and schools.