Wind Energy

Wind power is a clean, renewable energy source that can be converted to electricity using a wind turbine. Wind turbines operate by converting the kinetic energy of moving air to rotational motion by a rotor, or turbine blade, and then converting the rotational motion into electricity. The Department of Energy's Department of Energy Efficiency and Renewable Energy provides an animated demonstration.

Egg-beater style wind turbine.

Wind Turbine with three-blade design.

Wind turbines come in a wide variety of shapes and sizes. The two most common wind turbine models are a horizontal axis turbine, which uses a traditional three-blade design, and an eggbeater-shaped turbine that spins vertically. Industrial scale turbines may have blade diameters more than 80 meters (nearly the length of a football field) and can produce about 2 MW of power per turbine. Smaller turbines, of approximately 15 meter diameter or less, generate enough electricity for residential or farm use and can be purchased by individuals.

Wind farms are groups of industrial turbines located in close proximity. They can produce hundreds of MW of power and are usually connected to the electricity grid. Wind farm projects are operated by wind developers who negotiate with individual landowners the right to “harvest” wind from farms by stationing wind turbines on agricultural land or grazing pastures. Many factors affect the amount of electricity generated on a wind farm: wind speed, wind density, wind shear, season, time of day, etc. Nationwide, the installed wind capacity in 2006 was approximately 11 GW of power.

A private study conducted by the State Utility Forecasting Group at Purdue University in Indiana identified a variety of advantages and disadvantages to wind power. On the plus side, wind is an inexhaustible, non-polluting resource. It is also a source of income for farmers and landowners who lease their property to wind farms. However, the wind is an intermittent source of energy (since it is not always blowing). Moreover, many promising wind sites in the United States are located far from the demand centers and wind electricity is difficult to transmit and store. Scientists and leaders of industry are working constantly to improve and update wind technologies.

Sources:

• American Wind Energy Association Fact Sheet: Wind Power Today
• Energy Efficiency and Renewable Energy Program of the U.S. Department of Energy
• Indiana-specific wind power information
• Indiana Tall Towers Wind Study
• Purdue University’s State Utility Forecasting Group Renewable Resources Study