is a form of solar energy. Wind energy describes the process by which wind is used to generate electricity. Wind turbines convert the kinetic energy in the wind into mechanical power. A generator can convert mechanical power into electricity.
Wind is caused by the uneven heating of the atmosphere by the sun, variations in the earth’s surface, and rotation of the earth. Mountains, bodies of water, and vegetation all influence wind flow patterns, . Wind turbines convert the energy in wind to electricity by rotating propeller-like blades around a rotor. The rotor turns the drive shaft, which turns an electric generator. Three key factors affect the amount of energy a turbine can harness from the wind: wind speed, air density, and swept area.
Equation for Wind Power
- Wind speed
- The amount of energy in the wind varies with the cube of the wind speed. In other words, if the wind speed doubles, there is eight times more energy in the wind (). Small changes in wind speed have a large impact on the amount of power available in the wind .
- Density of the air
- The more dense the air, the more energy received by the turbine. Air density varies with elevation and temperature. Air is less dense at higher elevations than at sea level, and warm air is less dense than cold air. All else being equal, turbines will produce more power at lower elevations and in locations with cooler average temperatures.
- Swept area of the turbine
- The larger the swept area (the size of the area through which the rotor spins), the more power the turbine can capture from the wind. Since swept area is , where r = radius of the rotor, a small increase in blade length results in a larger increase in the power available to the turbine