Methane

A new study published by the Proceedings of the National Academy of Sciences suggests that EPA’s greenhouse gas inventory may be underestimating total methane emissions in the United States, possibly by as much as 50 percent. According to the authors, emissions from oil and gas production could be twice as high as EPA data suggest, if not higher. But it’s worth noting a few key facts about the study, including some additional context that should prevent all of us from leaping to any particular conclusion based on this limited research.

KEY FACT 1: Looks at old operating environment.

As Andy Revkin of the New York Times pointed out: “It’s important to note that the new study is a snapshot of conditions in 2007 and 2008, before concerns increased about the need for tighter standards for gas and oil drilling operations.” In the oil and gas industry, ignoring a half decade of research and innovation is almost comical, even more so because the researchers suggest that snapshot is somehow indicative of the current operating environment!

Don’t just take our word for it, either. Researchers from MIT found just last year that industry use of “green completions” (i.e. reduced emissions technologies) was far more common than previously thought. Research from the University of Texas earlier this year actually took direct measurements from well pads, and those data essentially confirmed EPA’s estimates — based on wide adoption of methane reducing technologies. Last but not least, there’s plenty of evidence to suggest that, if anything, EPA’s inventory actually overstates methane emissions, owing to the agency’s inflation of flowback periods and demonstrably false assumptions regarding flaring.

EPA revised its emissions estimates downward earlier this year based on more comprehensive data that had been collected since its previous inventory. That data, and EPA’s subsequent change, were the result of activities that have occurred after 2008, making that data much more relevant to today’s operating environment.

KEY FACT 2: What’s the actual source?

The researchers used aircraft and observation towers to collect emissions data, analyzed it, and then plugged those findings into a model to estimate what the source(s) could have been. Contrast this, for example, to the data collected in the UT/EDF study earlier this year, which were the result of direct measurements. In other words, Miller, et. al., does not tell us definitively where the methane is coming from, only a guess (albeit an educated one) based upon mathematical modeling.

Miller, et. al., used the presence of propane to link certain methane readings to oil and gas production, although this is more of an exercise in correlation than causation. “Cows don’t produce propane; oil and gas does,” said study co-author Marc Fischer. But propane doesn’t only get emitted when folks are drilling or completing wells, either. The California Air Resources Board, for example, has its own webpage describing how propane emissions from product transfers is an ozone concern. A study published in Science a few years ago found a variety of natural seepages “inject propane into the atmosphere.”

Does that mean the oil and gas industry was not responsible for any methane that has a propane fingerprint? Of course not. But as David Allen, the author of the UT/EDF study, told NBC News, “a logical follow-up question [to Miller, et. al.] is which sources within these sectors are responsible for the emissions.”

KEY FACT 3: More data mean better understanding.

The lead author of the study, Scot Miller, told NBC News that getting a handle on methane emissions “really requires a collaborative effort,” and that his study is one of many “different pieces of a much bigger puzzle.” That’s absolutely right, and as more research is done on this subject, we’ll all be better informed. Additional research allows us to make better policy decisions, and — this is worth stressing — the constant innovation occurring within the industry is a result of credible scientific research, including the $81 billion invested in emissions reductions technologies over the past 12 years by the oil and gas industry.

One study cannot tell us everything we need to know, and this latest research is no different.

Photo Credit: Methane and Facts/shutterstock