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Because electricity is lost as it is carried long distances, we begin an evaluation of the world wind by looking at where people use electricty. As a first-order approximation of where power is currently needed, we examine the earth at night. The image below reveals that the electric-using population is concentrated in a few world areas and is mostly along the coasts. This is more clear in the full-sized image--click below and scroll to your favorite world area(s). (Data courtesy Marc Imhoff of NASA GSFC and Christopher Elvidge of NOAA NGDC. Image by Craig Mayhew and Robert Simmon, NASA GSFC.)
The map below is a world, year-round average wind speed map. It is derived from 10 years of GEOS-1 sattelite data. Satellite data are the only wind data with global extent, but are less accurate because the data are indirect. Roughly 7 m/s and faster are economically worth exploiting today even in higher-cost offshore locations; those are the orange, pink, and shades of red and brown in the figure. In many areas, especially on land, the 6 m/s areas are already economically viable, those are the yellows. We see that the largest wind resources are above the oceans and mid-continental plains of each of the major continents. The coastal oceans are of special interest because they have strong winds and, as seen by the earth at night, they are close to most of the world's population and electric use. Full documentation on how these wind speeds are calculated can be found in NASA Surface meteorology and Solar Energy: Methodology, dated 12/16/04 (no author given but the PDF information says is written by "Chandler"). The map below is a year-round average. To see monthly fluctuations, click on this animation of monthly values.
Finally, we ask, how much of the vast ocean wind resource is likely to be tapped? Current offshore wind towers available today are rated to 20m water depth (some manufacturers say 30m). Designs now underdevelopment would extend this to the entire continental shelf areas (up to 150-200m depth). The designs we consider more likely to be practical and (eventually) economic involve teathers to the bottom and electrical cables connecting to shore, so we do not consider viable areas off the continental shelves. The map below locates the world's continental shelves, the darker reddish areas. Continental shelves are quite large off eastern North America, Western Europe, East Asia, and southeastern South America.
Globally, the resource is very large. In an in-press article, Archer and Jacobson use worldwide weather stations (more accurate than the above GEOS-1 data, but not covering the oceans) and estimate the
worldwide land and near-shore wind resource. Their calculation of total wind resource is 72 TW. This is seven tiems the world's electricity demand and five times
the world eneregy demand (all commercial fuels and carriers). Although the direct solar resource is larger, in the higher speed wind areas the wind resource is at or near
economic viability today.
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