• Wind energy is pollution-free.wind image by Byron Moore from Fotolia.com
  
  Wind is the fastest growing source of power in the world, according to the National Renewable Energy Laboratory. A wind turbine generation system, more commonly called a wind turbine or a wind turbine generator, is used to convert wind energy into mechanical power. A generator in the turbine then converts the mechanical power into electricity. The simplest wind turbines have three basic parts: the rotor blades, the shaft and the generator.
  
  

Blades

• There are two basic types of blades, the lifting style and the drag style. When wind blows over lifting style blades, it causes the blades to lift and rotate. This style blade is good at capturing strong, fast winds. Drag-style blades are flattened plates. This is the type of blade that was used on old Dutch windmills. Windmills aren't good at capturing strong winds. Blades are made from fiberglass and reinforced plastic because those materials are lightweight, noncorrosive, and resist wear and tear. Most wind turbines have two or three blades, but there are also single-blade turbines.
  
  

Shaft

• The blades are connected to a hub which, in turn, is connected to a low-speed drive shaft. Together, the blades and hub are called the rotor. The rotating blades make the low-speed shaft spin approximately 30-60 rotations per minute (rpm). The low-speed shaft is connected to a high-speed shaft via a gearbox that increases the speed of the spinning to about 1,000 to 18,000 rpm. This is the speed most generators need, in order to produce electricity. There are two main types of wind turbine designs. The blades on a horizontal-axis wind turbine turn around a shaft that's parallel to the ground. The blades of a vertical-axis wind turbine turn around an upright shaft.
  
  

Generator

• The generator changes mechanical energy into electrical energy. Generators come in different sizes, and the size of the generator helps determine how much electricity can be produced. Most generators produce 60-cycle AC electricity.
  
  

Other Parts

• Wind turbines operate between 8 miles per hour (mph) and 55 mph. A controller is used to start the turbine up and to shut it off. The controller receives information from an anemometer, a gauge that measures the speed and direction of the wind. A disc brake is used to stop the rotor in emergencies. The nacelle is the structure that houses the gearbox, low- and high-speed shafts, the generator, controller, and the brake. It sits on top of a tower. The wind turbine's tower can be freestanding or have guy wires to help keep it rigid. Towers are made from tubular steel, concrete, or steel lattice. Turbines can generate more electricity with taller towers because the speed of the wind increases with height. Upwind turbines have a yaw drive to keep the rotor facing into the wind. Downwind turbines don't need a yaw drive. A turbine with yaw drives needs a yaw motor to power it and a wind vane to measure the direction of the wind.