Page 202 - Geosystems An Introduction to Physical Geography 4th Canadian Edition

166 part I The Energy–Atmosphere System
F cus Study 6.1 Sustainable Resources
Wind Power: An energy resource for the Present and Future
The principles of wind power are ancient, but the technology is modern and the benefits are substantial. Scientists esti- mate that wind as a resource could poten- tially produce many times more energy than is currently in demand on a global scale. Yet, despite the available technol- ogy, wind-power development continues to be slowed, mainly by the changing poli- tics of renewable energy.
The Nature of Wind energy
Wind Speed (m · s–1) 0 to 0.9
1.0 to 1.9
2.0 to 2.9
3.0 to 3.9
4.0 to 4.9
5.0 to 5.9
6.0 to 6.9
7.0 to 7.9
8.0 to 8.9
9.0 to 9.9
10 and above
Horizontal resolution of 5 km
Power generation from wind depends on site-specific characteristics of the wind re- source. Favourable settings for consistent wind are areas (1) along coastlines influ- enced by trade winds and westerly winds; (2) where mountain passes constrict air flow and interior valleys develop thermal low-pressure areas, thus drawing air across the landscape; and (3) where localized winds occur, such as an expanse of rela- tively flat prairies, or areas with katabatic or monsoonal winds. Many developing countries are located in areas blessed by such steady winds, such as the trade winds across the tropics.
Where winds are sufficient, electricity is generated by groups of wind turbines (in wind farms) or by individual installations. If winds are reliable less than 25%–30% of the time, only small-scale use of wind power is economically feasible.
The potential of wind power in Canada and the United States is enormous
(Figure 6.1.1). Winds from the Canadian Prairies south through Texas alone could meet all Canadian and U.S. electrical needs.
On the eastern shore of Lake Erie sits a closed Bethlehem Steel mill, con- taminated with industrial waste until the site was redeveloped with eight 2.5-MW wind-power turbines in 2007 (Figure 6.1.2). Six more turbines were added in 2012, making this a 35-MW
Canadian Wind Atlas produced by the WEST system of Environment Canada www.windatlas.ca
05/2005
(a)
0 500
1000 KILOMETRES
Suitable For Power Development
flows southward. Downwelling also occurs in the high southern latitudes as warm equatorial surface currents meet cold Antarctic waters (Figure 6.20). As water then moves northward, it warms; areas of upwelling occur in the Indian Ocean and North Pacific. A complete circuit of these surface and subsurface currents may require 1000 years.
Ocean surface waters undergo “freshening” in the polar regions because water releases salt when frozen (the salt is essentially squeezed out of the ice structure), and is then salt-free when it melts. This ocean freshen- ing through the melting of sea ice is currently being ac- celerated by climate change. Increased rates of glacial and ice-sheet melting are producing fresh, lower-density
4.0 5.0 6.0 7.0 8.0 9.0 10.0
wind speed m·s–1 (b)
▲Figure 6.1.1 Wind speed maps for Canada and the United States. Areas with wind speeds greater than 6.5 m·s−1 are considered suitable for power development. (a) Wind-speed map of Canada showing average speeds measured 50 m above ground at a spatial resolution of 5 km. (b) Wind-speed map of the contiguous United States showing predicted average wind speeds at a height of 80 m above the ground. Map has a spatial resolution of 2.5 km. [(a) Canadian Wind Atlas produced by the WEST system of Environment Canada. www.windatlas.ca. Atlas canadien du vent produit avec WEST d’Environnement Canada. www.atlaseolien.ca. 05/2005. (b) NREL and AWS Truepower.]