BOULDER CITY, NV - MARCH 21: U.S. President Barack Obama speaks at Sempra U.S. Gas & Power's Copper Mountain Solar 1 facility, the largest photovoltaic solar plant in the United States on March 21, 2012 in Boulder City, Nevada. Obama is on a four-state tour promoting his energy policies. The Copper Mountain solar facility is the largest operating photovoltaic plant operating in the country. (Photo by Ethan Miller/Getty Images)
