Wind power works by converting wind into a useful form of energy such as electricity. Most people today thing of wind power in terms of turbines converting wind into electricity. However, wind power has been used throughout human history. A couple examples of this are sails on ships and windmills.
This page will cover wind power being used to power wind turbines for the generation of electricity. Wind turbines rely on good placement. Despite what you might think this means more than just being located in high wind area. Other considerations are availability of transmission lines, value of the energy produced, cost of land, land zoning, and environmental impact of construction and operation.
Home wind turbines usually exist by themselves but for wind farms the placement of turbines in relation to each other is critical to success. An example of this is turbines placed in a line with each other can result in noise resonance resulting in noise pollution. Sophisticated software is used to simulate a wind farm before construction begins to determine optimal placement of each turbine. Check out the environmental impact of wind power as well.
Many wind turbines, commercial and home, are connected to batteries so that electricity can be stored even while it’s not being used. Many electric devices in areas that would be difficult to connect to the grid will use small wind turbines with small batteries. An example would be an internet router in forest areas or parks.
Here is a wind turbine broken down into its base components with a description of each component below.
1. Blades: Most turbines have either two or three blades. Wind blowing over the blades causes the blades to “lift” and rotate.
2. Rotor: The blades and the hub together are called the rotor.
3. Pitch: Blades are turned, or pitched, out of the wind to keep the rotor from turning in winds that are too high or too low to produce electricity.
4. Brake: A disc brake which can be applied mechanically, electrically, or hydraulically to stop the rotor in emergencies.
5. Low-speed shaft: The rotor turns the low-speed shaft at about 30 to 60 rotations per minute.
6. Gear box: Gears connect the low-speed shaft to the high-speed shaft and increase the rotational speeds from about 30 to 60 rotations per minute (rpm) to about 1200 to 1500 rpm, the rotational speed required by most generators to produce electricity. The gear box is a costly (and heavy) part of the wind turbine and engineers are exploring “direct-drive” generators that operate at lower rotational speeds and don’t need gear boxes.
7. Generator: Usually an off-the-shelf induction generator that produces 60-cycle AC electricity.
8. Controller: The controller starts up the machine at wind speeds of about 8 to 16 miles per hour (mph) and shuts off the machine at about 65 mph. Turbines cannot operate at wind speeds above about 65 mph because their generators could overheat.
9. Anemometer: Measures the wind speed and transmits wind speed data to the controller.
10. Wind vane: Measures wind direction and communicates with the yaw drive to orient the turbine properly with respect to the wind.
11. Nacelle: The rotor attaches to the nacelle, which sits atop the tower and includes the gear box, low- and high-speed shafts, generator, controller, and brake. A cover protects the components inside the nacelle. Some nacelles are large enough for a technician to stand inside while working.
12. High-speed shaft: Drives the generator.
13. Yaw drive: Upwind turbines face into the wind; the yaw drive is used to keep the rotor facing into the wind as the wind direction changes. Downwind turbines don’t require a yaw drive, the wind blows the rotor downwind.
14. Yaw motor: Powers the yaw drive.
15. Tower: Towers are made from tubular steel or steel lattice. Because wind speed increases with height, taller towers enable turbines to capture more energy and generate more electricity.
Courtesy of U.S. Department of EnergySponsors: