Characterizing Fugitive Methane Emissions in the Marcellus Shale Region Using Mobile Measurements

Abstract

Natural gas, particularly shale gas, comprises a growing portion of US energy production and is thought of as a bridge fuel to renewable energy. Although natural gas emits much less carbon dioxide than other fossil fuels, methane leakage may offset the climate benefits of natural gas over other fuels. I collected atmospheric measurements via a mobile, on-road sampling method near 84 natural gas sites in the Marcellus shale region in order to estimate a methane leakage rate and characterize the distribution of emitters. I determined that measurements should be collected within 300 meters of the well pad and that a single pass may not be representative. Using inverse Gaussian plume modeling, the site leakage rates ranged from 0.1 to 2800 metric tons/year. The distribution was highly skewed, with the top 6% of sites contributing 60% of methane emissions. This finding emphasizes the need to locate and repair “superemitters” to retain the climate benefits of natural gas over other fossil fuels.