Article Photos: Fracking for natural gas being powered by it, too 4/7

In this photo made on Thursday, Jan. 17, 2013, technician Sean Cline works on securing a wiring harness as he finishes up the conversion of a 50 litre, 16 cylinder, Cummins diesel engine with four turbo-chargers that has been converted to run on a blend of diesel and natural gas at the Cummins Bridgeway facility in Gibsonia, Pa. Oil- and gas-field companies from Pennsylvania to Texas are experimenting with converting the huge diesel engines that operate pumps that propel millions of gallons of water, sand and chemicals down a well bore in the fracturing process to break apart rock or tight sands that trap natural gas. (AP Photo/Keith Srakocic)