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Aircraft-based Quantification of Individual Oil and Gas Facilities' Methane Emissions S. Conley 1,2 , S. Schwietzke 3,4 , G. Petron 3,4 , S. Wolter 3,4 , S.C. Herndon 5 , T.I. Yacovitch 5 , C. Sweeney 3,4 , W.B. Knighton 6 and I. Faloona 2 1 Scientific Aviation, Roseville, CA 95661; 916-217-1107, E-mail: [email protected] 2 University of California at Davis, Davis, CA 95616 3 Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, Boulder, CO 80309 4 NOAA Earth System Research Laboratory, Global Monitoring Division (GMD), Boulder, CO 80305 5 Aerodyne Research Inc., Billerica, MA 01821 6 Montana State University, Bozeman, MT 59717 Inventory-based (bottom-up) estimates of methane (CH 4 ) emissions from oil and gas operations have been evaluated recently in the U.S. using atmospheric data (top-down). Since top-down estimates are consistently larger than those from bottom-up approaches, more research is needed to explain this difference. This work focuses on top-down emission estimation at the facility-level using aircraft measurements. We estimated emission rates of isolated facilities by measuring CH 4 , ethane (C 2 H 6 ), and carbon dioxide (CO 2 ) dry air mole fractions in a closed circular path around each facility at multiple altitudes, and by employing Gauss’s theorem to integrate the trace gas flux normal to the flight path. This presentation focuses on measurements conducted to evaluate the estimation method: emission rate quantifications from (i) controlled (known) releases of C 2 H 6 , and (ii) power plants using published, plant-specific, hourly CO 2 emission rates. Existing results indicate that the method can accurately quantify emissions within less than 25% error. Figure 1. Flight path and CH 4 levels (color-coded) above an oil and gas facility indicating an isolated CH 4 source.

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Aircraft-based Quantification of Individual Oil and Gas Facilities' Methane Emissions

S. Conley1,2, S. Schwietzke3,4, G. Petron3,4, S. Wolter3,4, S.C. Herndon5, T.I. Yacovitch5, C. Sweeney3,4, W.B.Knighton6 and I. Faloona2

1Scientific Aviation, Roseville, CA 95661; 916-217-1107, E-mail: [email protected] of California at Davis, Davis, CA 956163Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, Boulder, CO803094NOAA Earth System Research Laboratory, Global Monitoring Division (GMD), Boulder, CO 803055Aerodyne Research Inc., Billerica, MA 018216Montana State University, Bozeman, MT 59717

Inventory-based (bottom-up) estimates of methane (CH4) emissions from oil and gas operations have beenevaluated recently in the U.S. using atmospheric data (top-down). Since top-down estimates are consistentlylarger than those from bottom-up approaches, more research is needed to explain this difference. This workfocuses on top-down emission estimation at the facility-level using aircraft measurements. We estimatedemission rates of isolated facilities by measuring CH4, ethane (C2H6), and carbon dioxide (CO2) dry air molefractions in a closed circular path around each facility at multiple altitudes, and by employing Gauss’s theoremto integrate the trace gas flux normal to the flight path. This presentation focuses on measurements conducted toevaluate the estimation method: emission rate quantifications from (i) controlled (known) releases ofC2H6, and (ii) power plants using published, plant-specific, hourly CO2 emission rates. Existing results indicatethat the method can accurately quantify emissions within less than 25% error.

Figure 1.

Flight path and CH4 levels (color-coded) above an oil and gas facility indicating an isolated CH4 source.