Flawed Methane Monitor Underestimates Leaks at Oil and Gas Sites

Researchers find there may be drastically more methane in the air than is being reported to industry and government.

A popular scientific instrument used to measure methane leaks from oil and gas operations severely underestimates emissions under certain conditions, a preliminary study found.  The results could have major implications for federal policies as the Obama administration moves to regulate methane from the natural gas industry.

The research paper raises serious questions about the validity of existing methane data.  Measurements taken by the instrument are frequently used by the Environmental Protection Agency to estimate industrial releases of methane—a greenhouse gas dozens of time more potent than carbon dioxide.  In fact, the EPA lists the device as an approved tool that oil and gas companies can use to measure and report their methane emissions.

"It could be a big deal," especially if it turns out the EPA is underestimating methane leaks, said study co-author Amy Townsend-Small, a geology professor at the University of Cincinnati. The paper was published in late March in the peer-reviewed Journal of the Air & Waste Management Association.

The instrument in question is the Bacharach Hi-Flow Sampler sold by Bacharach Inc.  The portable device, about the size of a large backpack, has been on the market since 2001 and is the only commercially available tool that allows scientists to take instantaneous measurements of methane emissions from pipelines, storage tanks and other natural gas facilities.  Each Bacharach costs around $20,000.  Alternative measurement methods are generally more costly or time-consuming.
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In addition to identifying the problem, the study authors found a possible solution.  The Bacharach sampler functioned correctly when calibrated daily and when it was installed with a specific version of the instrument's software released in April 2012.

The good news is the apparent solution shouldn't be hard to implement, said lead author Touché Howard, a semi-retired air quality consultant and firefighter who lives in Durham, N.C.
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Townsend-Small said the Bacharach's flaws could help explain the discrepancies between "top-down" and "bottom-up" methane studies.  In top-down studies, which generally find higher emissions, researchers take aerial measurements of the methane coming from regional oil and gas facilities.  In the bottom-up methodology, scientists take a limited number of direct measurements from industry sites and extrapolate the findings to a larger region.  Since Bacharachs are often used for on-site measurements, Townsend-Small said, this might contribute to the lower emissions found in bottom-up studies.

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