Estimating Methane Emissions From Underground Coal and Natural Gas Production in Southwestern Pennsylvania

Abstract

Production of coal and natural gas is responsible for one third of anthropogenic methane (CH4) emissions in the United States. Here we examine CH4 emissions from coal and natural gas production in southwestern Pennsylvania. Using a top‐down methodology combining measurements of CH4 and ethane, we conclude that while Environmental Protection Agency inventories appear to report emissions from coal accurately, emissions from unconventional natural gas are underreported in the region by a factor of 5 (±3). However, production‐scaled CH4 emissions from unconventional gas production in the Marcellus remain small compared to other basins due to its large production per well. After normalizing emissions by energy produced, total greenhouse gas emissions from Pennsylvania unconventional natural gas production produce half the carbon footprint compared to regionally produced coal, with carbon dioxide emissions from combustion being the dominant source of greenhouse gas emissions for both sources.

Estimating CH<sub>4</sub>, CO<sub>2</sub> and CO emissions from coal mining and industrial activities in the Upper Silesian Coal Basin using an aircraft-based mass balance approach

“…Here, airborne measurements reveal more detailed insights on smaller scales, because in situ measurements allow the study of emission sources with high spatial resolution and accuracy. Highprecision measurements of atmospheric concentration can be used for the top-down estimation of emissions from specific regions or sectors using atmospheric inversion models (Gurney et al, 2002;Thompson et al, 2014;Bergamaschi et al, 2018) and for the validation of numerical models used to calculate atmospheric abundances based on bottom-up emission inventories (Krinner et al, 2005;O'Shea et al, 2014). Airborne measurements provide highly valuable data for an independent assessment of anthropogenic CH 4 , CO 2 and CO emissions, because the majority of these emissions originate from a small fraction of the globe, namely fossil fuel exploitation facilities, cities and power plants.…”

Unmanned aerial vehicle observations of cold venting from exploratory hydraulic fracturing in the United Kingdom

“…Fracking emissions occur during three major phases (Allen et al 2013): recovery of fracking fluid prior to gas retrieval (flow-back), fluid recovery from well clearing during production (unloading) and leaks from gas refinement and distribution. Net gas loss from shale regions in the USA varies, from zero up to the order of a 10% leak rate, depending on the prevalence of fracking and the presence of processing facilities (Schneising et al 2014, Omara et al 2016, Barkley et al 2019, Ren et al 2019. Omara et al (2016) observed higher average emissions from 13 unconventional than 18 conventional gas extraction sites in the Marcellus shale formation in the USA, though unconventional extraction had a lower leak rate due to better productivity.…”

Estimating CH<sub>4</sub>, CO<sub>2</sub>, and CO emissions from coal mining and industrial activities in the Upper Silesian Coal Basin using an aircraft-based mass balance approach

“…Airborne measurements provide highly valuable data for an independent assessment of anthropogenic CH 4 , CO 2 and CO emissions, because the majority of these emissions originate from a small fraction of the globe, namely fossil fuel exploitation facilities, cities, and power plants. Airborne measurements have shown to be useful in emission assessment of anthropogenic emissions from several sectors, including landfills Krautwurst et al, 2017) and oil and gas production regions (Karion et al, 2015;Yuan et al, 2015;Alvarez et al, 2018;Barkley et al, 2019). Plant et al (2019) and Ren et al (2018) showed that North American cities emit more CH 4 than suspected, because of underestimation of natural gas leakage or lack of inclusion of end use emissions.…”