Methane emissions from hydraulic fracturing are much lower than the U.S. Environmental Protection Agency has estimated, according to a report released Monday by two oil and natural gas industry groups.
The American Petroleum Institute and America's Natural Gas Alliance found methane emissions to be 50 percent lower than the EPA estimated when it issued the first federal clean air standards for hydraulic fracturing in April.
Howard Feldman, API's director of regulatory and scientific affairs, said the industry's report did not find fault with the EPA's emissions factors, but rather its data on how frequently hydraulic fracturing is used to release oil and gas from dense rocks.
“We're just saying that, well, in fact, that process doesn't happen as often as EPA previously estimated,” Feldman said.
The industry survey focused on two large methane emissions categories: liquids unloading, or the process of removing liquids from the wellbore, and well refracturing, which helps existing wells keep producing.
The survey showed methane emissions from liquids unloading are 86 percent lower than the EPA estimated, and emissions from well refracturing are 72 percent lower.
Craig Segall, an attorney with the Sierra Club's environmental law program, said the industry's numbers, if they're correct, still mean natural gas development is a major contributor to greenhouse gas emissions.
He said most of the methane leaks from gas development are controllable, creating another revenue source for producers if they make changes as prescribed by the new EPA rules, which go into effect in 2015.