Are Malfunctioning Monitors Underestimating Methane Emissions?

The rate of methane leakage from gas wells could determine the future of our energy supply. Hillebrand Steve/U.S. Fish and Wildlife Service.

It seems like an obscure and technical debate, but a new paper has raised the possibility that measurements of methane leakage when drilling for natural gas are severely flawed. If correct, the paper will throw global energy plans into chaos, and while it is just one shot in a long-running war, the paper is already attracting some independent support.

As the world moves to replace coal as the primary source of electricity, natural gas is often the cheapest solution. At its best, however, gas is still responsible for half of the carbon dioxide emissions per megawatt as coal generates.

Moreover, methane (CH4), the main constituent in natural gas, has 28 to 36 times the global warming potential of carbon dioxide over a century. If even a few percent of natural gas tapped for energy leaks, any climate advantage gas has over coal evaporates. This makes the question of how much leaks absolutely crucial.

Estimates here vary; measurements have been taken ranging from 0.1% to 10.1%, but average performance is far more important than the extreme cases. Unsurprisingly this has been hard to obtain. Reports of methane clouds in drilling regions lend weight to the higher estimates, but are difficult to quantify.

So the industry welcomed a 2013 study by the University of Texas, sponsored by the Environmental Defense Fund, that found 0.42% leakage from 190 wells. This study has now been challenged in Energy Science and Engineering.

The problem, according to Touché Howard, is that the Texas study was done using the Bacharach Hi-Flow Sampler (BHFS) to measure methane around well heads. Howard argues that the BHFS “has been shown to exhibit sensor failures leading to underreporting of [Natural Gas] emissions.”

The BHFS has two samplers, one of which measures very low levels of gas, the other designed to test higher concentrations. Sometimes, Howard argues, the high concentration sampler fails to turn on, producing measurements that can be too low by a factor of 100. “Although this failure is not well understood,” Howard claims, “It does not seem to occur when measuring pure CH4 streams, but has been observed in four different samplers when measuring streams with CH4 contents ranging from 66% to 95%.”

Howard goes into considerable detail on the record of BHFS failure, and why it is likely to have occurred in many of the University of Texas measurements. The New York Times reports that even the manufacturers of the BHFS, while skeptical of Howard’s claims, acknowledge that their device was validated on different sorts of gas streams from those at wellheads, and may need further testing.

Some leaks during natural gas extraction can be fixed relatively cheaply, potentially leaving gas on the table as a fuel for the future. However, others are thought to be harder to plug, and if Howard is right that these are much larger than previously recognized, it is possible that governments will need to abandon energy transitions plans that involve using gas as a transition fuel between coal and renewables.

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