A horizontal wind turbine creates electricity from wind power. It is made of several interdependent parts. The wind is collected by two or three rotating blades connected to a tower by a hub or rotor. Surrounding the hub are a computerized yaw system to hold the turbine into the wind, a generator, a gearbox and a nacelle to protect all parts from the elements. A tower supports the entire mechanism.
Rotor with Blades
Most wind turbines have two or three blades connected to a rotor, a round metal plate. Blades can be as long as 240 feet. Although blades are made of aluminum or wood on smaller wind turbines, most large wind turbine blades are made of composites. Blades reaching 150 feet or more are often made of fiberglass or epoxy composites and, more recently, carbon fiber.
Computerized Yaw System
The yaw angle is the difference between the actual wind direction and the angle of the turbine. In order to keep this to a minimum, a tailvane attached to the back of the nacelle detects the wind direction and relays the proper steerage to a computer. This computer constantly steers the wind turbine toward the wind for maximum utilization.
Wind turbines use generators to convert the mechanical energy of the turning rotor into electrical energy. This is done by magnets within the rotor passing over metal coils (usually copper). The resulting electricity then is sent through wires to the utility grid. Most generators use AC power. However, more recently, technology has changed so that variable frequency current caused by inconsistent wind speeds is converted to DC and then AC using a converter.
Often the wind turbine rotates at a slower speed than the electrical network. Wind generators rotate about five to 20 revolutions per minute, and the the electrical network speed is 750 to 3,600 rpm. Different-size gears are used to compensate for such a difference within the gearbox located between the rotor and the hub.
Wind speeds increase with height. The higher the wind turbine, the more electricity is produced. A recommended height is between 80 to 100 feet. Three main towers are used with wind turbines. Guy lattice towers are least expensive but need more space with their required guy wires. Guyed tilted towers are able to be raised and lowered for maintenance. Self-supporting towers without guy wires are costly but take up the least space.
- Photo Credit Wind Turbine image by Towards Ithaca from Fotolia.com rotor d une Ã©olienne image by laurent007 from Fotolia.com wind mill image by David Sexton from Fotolia.com windmill generator image by Yali Shi from Fotolia.com GEARS IN MOTION image by AL MOUNT from Fotolia.com aeromotors image by Nikolai Sorokin from Fotolia.com