FILE - In this Feb. 21, 2012, file photo, oil field workers drill into the Gypsum Hills near Medicine Lodge, Kan., using a technique known as hydraulic fracturing, or "fracking", to coa

 

              FILE - In this Feb. 21, 2012, file photo, oil field workers drill into the Gypsum Hills near Medicine Lodge, Kan., using a technique known as hydraulic fracturing, or "fracking", to coa
FILE - In this Feb. 21, 2012, file photo, oil field workers drill into the Gypsum Hills near Medicine Lodge, Kan., using a technique known as hydraulic fracturing, or "fracking", to coax out oil and gas. The nation's newfound reserves of natural gas can help offset the economic cost of importing oil. Delivery trucks, garbage trucks and some long-haul trucks are beginning to switch to cheaper natural gas and away from oil-derived diesel. And several companies are applying for permits to export natural gas to Europe and Asia. (AP Photo/Orlin Wagner, File)