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Windfall Ecology Centre
Wind energy basics
Wind is powered by the sun. In fact, all renewable energy, and even energy in fossil fuels, ultimately comes from the sun. The sun heats our planet to different temperatures in different places and at different times. This unequal distribution of heat is what creates wind as warm air rises and cooler air descends to fill the void. Wind is the ongoing movement of this air.
As the sun warms the earth, it in turn, warms the air above it, making it less dense or lighter. As the light air rises, it creates a low pressure zone near the ground. Air from surrounding cooler areas rushes in to balance the pressure. These are called local winds. Temperature differences between the polar caps and equator, as well as the rotation of the earth, produce similar results on a global scale, called prevailing winds.
Capturing the wind
Wind turbines come in many sizes, from small to large but the ones seen in Canada today generally consist of large blades mounted on tall towers attached to a horizontal shaft. As the wind blows, these blades cause the shaft to turn. The shaft is attached to a generator located inside the head, or “nacelle” of the turbine, which generates electricity. Cables carry this electrical current to transmission lines that then carry it to homes and businesses. Modern turbines rotate quite slowly, at an average speed of between 18 to 20 revolutions per minute
Maintenance issues are also much smaller on a wind farm. At some conventional power plants, the entire plant may have to be shut down for repairs whereas at a wind farm, maintenance takes place one turbine at a time. This has led to availability factors (referring to the percent of time that a turbine is available to capture the wind) of 98% – much higher than conventional forms of energy production.
Wind turbines can also be non-grid connected and used for supplying power to a home, farm, cottage, or even remote community. These, generally smaller turbines are discussed in the 'Small wind energy systems' section below.
Information adapted from the Canadian Wind Energy Association, 2009.
Small wind energy systems
Small wind energy systems can be used to help meet the electricity needs of rural or off-grid homes either by themselves or in combination with other renewable energy sources such as solar panels. The most important factor to consider when thinking of purchasing a small wind energy system is siting. Improperly sited turbines, such as those installed on too low a tower and/or in an area with many obstructions (such as buildings and trees) will produce very little energy (see the CanWEA Small Wind Purchasing Guide for more information).
For additional information on small wind systems, consider attending the: Green Energy Introduction one-day course at the Kortright Centre for Conservation in Vaughan.