The closure of seven coal-fired electric plants in four states could be a sign of things to come as tough new emissions standards threaten to relegate America’s top energy source to the back burner. FirstEnergy Corp., headquartered in Ohio, closed power plants on Saturday in Albright, Rivesville, and Willow Island, W.Va., along with four others in Ohio, Maryland and Pennsylvania as the company phases out aging facilities that cannot comply with new environmental regulations. Three others in Ohio also will be closed in 2015, company officials told FoxNews.com. “We estimate that it will cost approximately $975 million to make our...