Canadian Geographic
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INSIDE: Small-Scale Wind Go now!

Small-scale wind turbines, designed for residential, rural or agricultural use, represent a growing segment of the renewable energy market, but still account for a tiny fraction of the overall output from wind energy facilities.

The earth’s most abundant source of energy is the sun. Wind, as an atmospheric phenomenon, is simply solar power in a different form.

Heat from the sun causes “convection” in the atmosphere, meaning that heated air rises. These currents create zones of high and low air pressure within the atmosphere. “As the light air rises, it creates a low pressure zone near the ground,” according to the Canadian Wind Energy Association (CanWEA). “Air from surrounding cooler areas rushes in to balance the pressure.” These horizontal pressure differences account for ambient wind and more intense storm wind.

“Prevailing winds,” in turn, are caused by the temperature differences between the earth’s poles and its equatorial regions, as well as its rotation. The earth’s atmosphere, in fact, has several very large and steady prevailing wind channels, such as the “polar easterlies” and the “northeast trades.” In North America, one of the dominant prevailing wind paths tracks in a south-east arc from the northern Prairies towards the Great Lakes and the eastern seaboard.

Wind energy is also affected by other factors. Air currents move faster and more consistently at higher altitudes – think of the blustery conditions at the tops of tall buildings or on mountain tops. Similarly, wind tends to gather energy when it moves unimpeded over longer distances, which is why very flat regions, such as the prairies, tend to be highly exposed to intense wind.

All of these traits have a bearing on the way wind energy can be tapped. While we experience breezes just about everywhere on the planet, only some regions are sufficiently gusty to generate enough wind energy to power turbines and create meaningful quantities of electricity. In Canada, those areas include southern Alberta, the coasts of the Great Lakes, and Quebec’s Gaspe Peninsula. As CanWEA says, “With the longest coastline in the world (243,792 km or 151,485 miles) and some of the world’s largest open prairies, we have one of the best wind resources in the world.”


On the next page:

The History of Windmills and Wind Turbines

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Quiz :

When air flows over open water how does its speed change?

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