the bulk of the shale gas.The problem, though, is that methane is a potent greenhouse gas as well as a fuel, and large amounts of it leak from shale-gas extraction, said the study.During the life cycle of an average shale-gas well, between 3,6% and 7,9% of the well???s total production is emitted to the atmosphere as methane, it said.This comes through routine venting, equipment leaks and emissio