Methane Emissions
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Methane Emissions Have Risen in Marcellus Shale Region

Despite a slowdown in the number of new natural gas wells drilled in the Marcellus Shale region of Northeast Pennsylvania, a study led by Drexel University researcher Peter DeCarlo, PhD, finds that atmospheric methane levels in the area are still increasing.

“Methane is increasing globally, but the rate of increase for this region is much more rapid than global increases,” says DeCarlo, an associate professor who studies atmospheric chemistry in Drexel’s College of Arts and Sciences and College of Engineering. “The rapid increase in methane is likely due to the increased production of natural gas from the region, which has risen significantly over the 2012 to 2015 period. With the increased background levels of methane, the relative climate benefit of natural gas over coal for power production is reduced.”

In contrast, the Pennsylvania Department of Environmental Protection’s 2015 Emissions Inventory (PADEPEI) report for unconventional natural gas emissions estimated a decrease in emissions from 2012 to 2015.

“Our measurements indicate that emissions of methane rose by roughly 300 percent,” says DeCarlo. “Thus, it is important to identify where in the PADEPEI there are flaws in estimating emissions, and how to address them.”

Since the first shale gas wells were drilled in the Marcellus Shale Basin, a region that diagonally bisects the state from the northeast to the southwest, there have been concerns about what unlocking the new stores of fossil fuel by an unconventional method, called hydraulic fracturing, could mean for the environment. Though it has been around since the mid-20th century, hydraulic fracturing is highly controversial. Maryland became the first U.S. state with gas reserves to ban the practice in March of 2017.

Overall, natural gas production from the Marcellus Shale region has climbed to 16 billion cubic feet per day, which is twice as much as any other unconventional natural gas resource in the country, according to the researchers.

“Though the rate at which new wells are being drilled and completed has slowed down, the overall infrastructure and production has increased,” DeCarlo says. “That means that the volume of gas moving through pipelines, compressor stations and processing plants is increasing. Since pipeline emissions are not included in the PADEPEI, this is one area where methane leakage may be significant and is being overlooked.”

This finding could suggest that measures taken by natural gas producers to decrease leakage from well completions, while still necessary, are not sufficient to reduce methane leakage in the Marcellus Shale region. And with the bulk of environmental protection regulations from the Pennsylvania Department of Environmental Protection focusing on ground water contamination, it is possible that atmospheric emissions from the natural gas infrastructure could persist until research can more clearly identify the source of the leaks and the effect of specific emissions on public health.

Photo by Nicolas A. Tonelli (CC/Flickr)

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