How is wind power produced?
Wind turbines harness the wind to generate electricity. Wind turns the turbine blades, which spin a shaft, which connects to the generator and makes electricity. A local transformer is then used to step up the electrical voltage, so that the electricity can then be sent through transmission and distribution lines to homes, businesses and other users.
Wind turbines generally produce electricity when winds blow at speeds of 13 kilometres an hour or greater. They shut down at above 90 kilometres per hour for safety reasons.
Wind turbines can also be used to generate mechanical power for specific tasks such as grinding grain or pumping water. On the Canadian Prairies, for example, there are several thousand wind turbines that pump water.
Basic components of wind turbines
Electricity-producing wind turbines have four basic components:
- a rotor consisting of two or three blades attached to a hub
- a generator that produces electricity in the form of alternating current
- a control and protection system that optimizes performance and keeps the machinery operating within safe limits
- a tower that raises the rotor off the ground.
Modern wind turbines make use of very few but very large blades (ranging between 40 to 80 metres in diameter) to capture wind energy, extracting energy from the largest possible volume of air. The blades are set at different angles to cope with varying wind speeds, and the generator and the blades can be turned to face the changing direction of the wind. The turbines are mounted on towers 40 to 80 metres tall, so as to capture stronger wind flows.
Two types of turbines
Modern turbines fall into two basic groups: horizontal axis turbines and vertical axis turbines.
Horizontal axis turbines resemble airplane propellers, with two to three rotor blades fixed at the front of the tower and facing into the wind. This is the most common design found today, making up most of the large utility-scale turbines on the global market.
Vertical axis turbines resemble a large eggbeater with rotor blades attached vertically at the top and near the bottom of the tower and bulging out in the middle.
Sizes of turbines
Wind turbines come in different sizes and can be used in small-scale and large-scale applications.
Single small turbines, up to 300 kilowatts, can be used in a variety of applications, including battery charging, providing power to remote cottages or communities, and powering farms and industrial facilities. These turbines are sometimes combined with other energy sources such diesel generators and solar photovoltaic systems to provide a reliable source of power.
Utility-scale turbines, 500 kilowatts and larger, provide power to the electricity grid. These are often grouped together in wind farms or wind power plants. By grouping wind turbines into wind farms, it is possible to generate electricity more economically and to produce enough electricity to power thousands of homes. It can also be more cost-effective to maintain and operate turbines.
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