A report recently released by the University of Texas’ Cockrell School of Engineering, “Measurements of methane emissions at natural gas production sites in the United States,” has re-energized the debate between industry and environmental groups over whether natural gas is good for the environment.
UT’s report is a peer-reviewed paper reporting on the results of measurements of methane emissions at 190 onshore natural gas sites in the US. It was sponsored by the Environmental Defense Fund, Anadarko Petroleum, BG Group, Chevron, Encana, Pioneer Natural Resources, Shell, Southwestern Energy, Talisman Energy USA, and Exxon. The study is part of a larger series of studies being sponsored by EDF to determine how much methane is emitted by natural gas exploration, production and transportion in the US. The issue is important because, on the one hand, burning of methane releases less carbon dioxide into the atmosphere than coal or oil, and on the other hand, methane is itself a powerful greenhouse gas that contributes to global warming. Over the first 20 years after it is released, methane is 72 times more potent than carbon dioxide as a greenhouse gas.
Those environmental groups who oppose further development of hydrocarbon resources argue that, because of methane emissions, natural gas is not a good alternative to other fossil fuels. They have argued, based in part on estimates of methane emissions from completion operations on wells using hydraulic fracturing, that the increased development of natural gas resources made possible by fracing is bad for the environment. The industry, and some environmental groups, see natural gas as a plus, a “bridge fuel” to development of renewable energy.
The debate over the greenhouse effect of methane was triggered by the release of a study by two Cornell University professors, Robert Howarth and Anthony Ingraffea, contending that EPA estimates of methane emissions were low, and that because of those emissions natural gas was a worse greenhouse gas than carbon dioxide and other emissions from burning coal. Howarth’s study has been widely criticized for using old data and vastly inflating methane emission estimates by the US Energy Department, the University of Maryland, MIT, Carengie Mellon Universty and the Worldwatch Institute.
Howarth has issued a press release criticizing the UT study, saying it relied on data from the nine companies who helped sponsor the study. He pointed to a study published last month by the National Oceanic and Atmospheric Administration (NOAA) as more representative of a worst-case scenario. It studied air emissions in an entire basin in Utah. “They’re finding methane emissions that are 10 to 20 times higher than this new study,” Howarth says, “and I think [that’s] probably more representative of at least those western gas fields, when industry does not realize it’s being watched.”
UT was criticized last year over possible bias in a study published by UT Austin’s Energy Institute, “Fact-Based Regulation for Environmental Protection in Shale Gas Development.” After review by an independent commission appointed by the University, UT withdrew the study. Its author had failed to reveal that he sits on the board of Plains Exploration and received substantial compensation from the company. The review panel concluded that the report was not “fact-based” or subject to serious peer review and that a summary press release of the report was misleading and “seemed to suggest that public concerns were without scientific basis and largely resulted from media bias.” (See my report on the controversy here.)
So what does the new UT study really tell us? Its measurements of methane released from completion and fracing operations are substantially lower than EPA’s estimates. But its measurements of gas released from pneumatic pumps and controllers and equipment leaks were either comparable to or higher than EPA estimates. Overall, the study’s estimates of methane emissions were in line with EPA’s most recent estimates. Lower measurements of emissions from well completions may be a result of better completion techniques that capture more methane, either for sale or flaring. UT’s study also attempted to measure methane emissions from “well unloadings”; while it found emissions from those events to be substantial, it concluded that its sample size was not sufficient to extrapolate emissions from that source and more sampling would be necessary. For a good explanation of emissions from “well unloadings” and well completions, you can watch the video on UT’s website explaining its study. EDF’s website explaining its efforts to better measure methane emissions is also instructive.
The debate continues.