"According to PFC Energy, a consulting firm to energy companies, shifting 10 percent of U.S. electricity sources to wind power would require wind farms covering an area the size of South Dakota …"
This is flat wrong. Here is a quick back-of-the-envelope calculation. This year, the 35,000 megawatts (MW) of wind power installed in the U.S. as of the end of 2009 will generate roughly 2.5% of U.S. electricity.
To generate 10% would require 4 times as much wind farm, or 140,000 MW (a generous number, it’s actually somewhat less). Again figuring generously, the land requirement is about 1 square mile for 10 MW, which means that the total land requirement would be, at the outside, 14,000 square miles, or less than one-fifth of the area of South Dakota (77,000 square miles).
Further, only 2-5% of that land would actually be occupied by wind turbines, access roads, etc.–the other 95-98% could still be used for farming or ranching.
By Tom Gray, www.awea.org/blog/