It is a device that converts the wind’s kinetic energy into electrical energy. Wind turbines are manufactured in a wide range of vertical and horizontal axis. The smallest turbines are used for applications such as battery charging for auxiliary power for boats or caravans or to power traffic warning signs. Larger turbines can be used for making contributions to a domestic power supply while selling unused power back to the utility supplier via the electrical grid.
Wind turbines operate on a simple principle. The energy in the wind turns two or three propeller-like blades around a rotor. The rotor is connected to the main shaft, which spins a generator to create electricity.
- Blades: Lifts and rotates when wind is blown over them, causing the rotor to spin. Most turbines have either two or three blades.
- Rotor: Blades and hub together form the rotor.
- Low speed Shaft: Turns the low-speed shaft at about 30-60 rpm.
- Gear Box: Connects the low-speed shaft to the high-speed shaft and increases the rotational speeds from about 30-60 rotations per minute (rpm), to about 1,000-1,800 rpm; this is 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.
- High Speed Shaft: Drives the generator.
- Generator: Produces 60-cycle AC electricity; it is usually an off-the-shelf induction generator.
- Anemometer: Measures the wind speed and transmits wind speed data to the controller.
- Controller: Starts up the machine at wind speeds of about 8 to 16 miles per hour (mph) and shuts off the machine at about 55 mph. Turbines do not operate at wind speeds above about 55 mph because they may be damaged by the high winds.
- Pitch System: Turns (or pitches) blades out of the wind to control the rotor speed, and to keep the rotor from turning in winds that are too high or too low to produce electricity.
- Yaw Drive: Orients upwind turbines to keep them facing the wind when the direction changes. Downwind turbines don’t require a yaw drive because the wind manually blows the rotor away from it.
Wind is a form of solar energy caused by a combination of three concurrent events:
- The sun unevenly heating the atmosphere
- Irregularities of the earth’s surface
- The rotation of the earth.