Wind Energy

The kinetic energy in wind can be converted into mechanical or electrical power. For centuries, windmills have converted wind energy into mechanical power to grind wheat into flour. Now, improved turbine technology allows wind generators to affordably produce electricity. Electricity is produced when an electrical conductor moves perpendicularly to a magnetic field. Generators have a conductor (or rotor) that spins inside a magnetic field (or stator). The challenge is to find abundant, low-cost energy to spin the rotor.

Wind generates less than 1 percent of the world's electricity, but is its fastest-growing energy source.

Hydroelectricity is a renewable energy source that uses the potential energy of falling water to turn the rotor. Wind is also a renewable energy source because its supply is not depleted after being used. Generators also use nuclear or fossil fuels to convert water into steam pressure, which turns the rotor. Fossil fuels like coal are essentially nonrenewable because they form over millions of years. Although wind is renewable, it is not always reliable. Wind velocity may fluctuate or fall below the minimum annual average velocity of 13 miles per hour needed to generate electricity.

Wind is created when solar radiation interacts differentially with clouds, vegetation, and water bodies to unevenly heat the earth's surface. Resulting atmospheric pressure differences force air from high to low pressure areas. Wind velocity, density, and temperature determine wind quality. Winds aloft are better than surface winds. Hills, valleys, and other geomorphic features can locally increase or decrease the relative velocity.

Wind energy potential depends on the area swept by the wind, its density, and velocity. Blade length and rotor design define the area component for a turbine. Denser air will also have an impact by generating more momentum. Velocity is the primary [Page 1969]factor in wind power generation because changes in velocity have a cubed effect on power.