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.
The EPA's rules are based on data from the agency's 2010 Greenhouse Gas Inventory Report.
The new industry survey, which is based on data collected in 2010 and 2011, did not require new emissions measurements because Feldman said it would have been too costly to take measurements at hundreds of thousands of locations.
He said the EPA did not survey enough wells to form a representative sample size.
The agency said there are about 355,000 gas wells in the United States, but its survey included only 8,800 wells.
The industry groups surveyed 91,000 wells.
The new report included responses from 19 of 21 “significant” basins, which are basins with more than 1 percent of total national gas wells.
Feldman said the report was prepared by independent contractors Terri Shires of the URS Corp. and Miriam Lev-On of the Levon Group.
“We're as much hands-off as we can be on this kind of thing,” Feldman said. “People want industry … to have responsibility and do studies and try to understand our emissions, so we're doing that.”
Sara Banaszak, vice president and chief economist at ANGA, said the report was released as soon as it was ready, about six weeks after the EPA issued its standards.
Feldman said he was not prepared to address whether API would challenge the rules in court.
CONTRIBUTING: Jay F. Marks, Business Writer