U.S. power generator GenOn Energy Inc on Wednesday said it would deactivate 3,140 megawatts of mostly coal-fired generating capacity in Pennsylvania, Ohio and New Jersey by 2015 due to more stringent federal environmental regulations. Over the past few years, energy companies have announced the shutdown or planned retirement of more than 30,000 megawatts (MW) of coal-fired generation due to proposed more stringent federal environmental regulations, weak power market conditions and record switching from coal to natural gas-fired generators as gas prices hold near 10-year lows.