A 2007 Department of Energy study found the potential for 135,000 megawatts of combined heat and power (which uses energy recovery) in the U.S., and a Lawrence Berkley National Laboratory study identified about 64,000 megawatts that could be obtained from industrial waste energy, not counting CHP. These studies suggest that about 200,000 megawatts, or 20%, of total power capacity could come from energy recycling in the U.S. Widespread use of energy recycling could therefore reduce global warming emissions by an estimated 20 percent. Indeed, as of 2005, about 42% of U.S. greenhouse gas pollution came from the production of electricity and 27% from the production of heat.