Reuters: The number of U.S. workers in environmental fields such as renewable energy and cutting air pollution has grown quickly over the past decade but the country needs a comprehensive energy plan for sector to meet its full potential, a Pew Center report said on Wednesday. Clean economy jobs grew at a national rate of 9.1 percent from 1998 to 2007 to 770,385, while overall jobs grew 3.7 percent during that time, the study said. Despite the recession, innovation and competition in …