Analysis of Oil and Gas Ethane and Methane Emissions in the Southcentral and Eastern United States Using Four Seasons of Continuous Aircraft Ethane Measurements
Journal Article
Overview
abstract
In the last decade, much work has been done to better understand methane; (CH4) emissions from the oil and gas (O&G) industry in the United; States. Ethane (C2H6), a gas that is co-emitted with thermogenic sources; of CH4 , is emitted in the US almost entirely by the O&G sector. In; this study, we perform an inverse analysis on 300 hours of atmospheric; boundary layer C2H6 measurements to estimate C2H6 emissions from the US; O&G sector. Measurements were collected from 2017-2019 as part of the; Atmospheric Carbon and Transport (ACT) America aircraft campaign and; encompass much of the central and eastern United States. We find that; for the fall, winter, and spring campaigns, C2H6 data consistently; exceeds values that would be expected based on EPA O&G leak rate; estimates. C2H6 observations from the summer 2019 dataset show; significantly lower C2H6 enhancements in the southcentral region that; cannot be reconciled with data from the other three seasons, either due; to complex meteorological conditions or a temporal shift in the; emissions. Converting the fall, winter, and spring season posterior C2H6; emissions estimate to an inventory of O&G CH4 emissions, we estimate; that O&G CH4 emissions are larger than EPA inventory values by more; than 50%. Uncertainties in the gas composition data limit the; effectiveness of using C2H6 as a proxy for O&G CH4 emissions. These; limits could be resolved retroactively by increasing the availability of; industry-collected gas composition data.
