San Francisco Chronicle: Windmills spinning over the Great Plains and along the coasts could supply 20 percent of U.S. electricity by the year 2030 and put a significant dent in greenhouse gas emissions, federal officials said Monday. Although wind farms now generate just 1 percent of the nation’s electricity, a new report from the U.S. Department of Energy found that wind power could play a far larger role in the future. It could supply roughly the same percentage of the nation’s power as nuclear plants …