FILE - In this June 25, 2012 file photo, a crew works on a gas drilling rig at a well site for shale based natural gas in Zelienople, Pa. It sounds like a free-market success story: a n

FILE - In this June 25, 2012 file photo, a crew works on a gas drilling rig at a well site for shale based natural gas in Zelienople, Pa. It sounds like a free-market success story: a new gas drilling boom driven by hydraulic fracturing, or fracking, which delivers a vast new source of cheap energy without the government subsidies that solar and wind power demand. But men who helped pioneer fracking recall a different story. From the shale fields of Texas and Wyoming to the Marcellus in the northeast, the U.S. Department of Energy contributed more than $100 million in direct federal research to help develop fracking, and Congress added $10 billion in tax breaks. Now, some of the biggest supporters of shale gas say the government should continue to back renewable energy research - for decades, if need be - to deliver future breakthroughs in that field. (AP Photo/Keith Srakocic)