CHARLESTON, W.Va. -- A major study out this week has provided valuable new data about the global warming pollution from natural gas production, but still leaves unanswered questions about the climate change impacts of an industry that's booming in West Virginia.
University of Texas researchers found slightly lower overall emissions rates for the powerful greenhouse gas methane than previously estimated by the U.S. Environmental Protection Agency and other scientific studies.
Working with industry and the Environmental Defense Fund, the researchers measured actual emissions from parts of the natural-gas production process at 190 sites around the country.
Their much-anticipated results were published Monday in the prestigious Proceedings of the National Academy of Sciences.
The findings will be closely scrutinized by policymakers and by all sides of the issue, as the Obama administration hopes increased use of natural gas - generally thought to be a clean alternative to coal - as part of a plan to combat potentially devastating impacts of climate change.
"This study tackles one of the most hotly debated issues in environmental science and policy today," said Mark Brownstein, associate vice president and chief counsel at EDF's climate and energy program. "It shows that when producers use practices to capture or control emissions ... methane can be dramatically reduced."
The research team, led by UT chemical engineer David Allen, found much lower than previously estimated methane emissions from well-completion flowbacks, when liquids used in the process are cleared from the wells.
Allen said those results shows that emerging regulatory requirements and improved industry operating practices are making a difference in driving down methane emissions.
"The way in which wells are drilled and brought into production has been evolving," Allen said.
But the team also found higher emissions from some pneumatic pumps used for controlling mechanical devices at well sites and from other equipment leaks, areas that the authors said warrant more attention by scientists and the industry.
For the specific emissions sources examined, the new study measured 957 gigagrams of methane. That compares to about 1,200 gigagrams estimated in the lasted EPA inventory. But the new study listed sampling and measuring uncertainties of plus or minus 200 gigagrams.
"The research did reveal some areas where emissions might be higher than expected, but there were also many areas where emissions were significantly lower, and the overall picture is obviously very reassuring," said Steve Everley, spokesman for the industry group EnergyInDepth.
In their push for more natural gas, drilling operators are increasingly using a process called hydraulic fracturing, or fracking, which shoots vast amounts of water, sand and chemicals deep underground to break apart rock and release the gas. More frequently, this process also involves drilling down and then turning horizontally to access more gas reserves.