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Assessment of Regional Methane Emissions Inventories through Airborne Quantification in the San Francisco Bay Area

Guha, Abhinav and Newman, Sally and Fairley, David and Dinh, Tan M. and Duca, Linda and Conley, Stephen C. and Smith, Mackenzie L. and Thorpe, Andrew K. and Duren, Riley M. and Cusworth, Daniel H. and Foster, Kelsey T. and Fischer, Marc L. and Jeong, Seongeun and Yesiller, Nazli and Hanson, James L. and Martien, Philip T. (2020) Assessment of Regional Methane Emissions Inventories through Airborne Quantification in the San Francisco Bay Area. Environmental Science and Technology, 54 (15). pp. 9254-9264. ISSN 0013-936X. doi:10.1021/acs.est.0c01212.

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This study derives methane emission rates from 92 airborne observations collected over 23 facilities including 5 refineries, 10 landfills, 4 wastewater treatment plants (POTWs), 2 composting operations, and 2 dairies in the San Francisco Bay Area. Emission rates are measured using an airborne mass-balance technique from a low-flying aircraft. Annual measurement-based sectorwide methane emissions are 19,000 ± 2300 Mg for refineries, 136,700 ± 25,900 Mg for landfills, 11,900 ± 1,500 Mg for POTWs, and 11,100 ± 3,400 Mg for composting. The average of measured emissions for each refinery ranges from 4 to 23 times larger than the corresponding emissions reported to regulatory agencies, while measurement-derived landfill and POTW estimates are approximately twice the current inventory estimates. Significant methane emissions at composting facilities indicate that a California mandate to divert organics from landfills to composting may not be an effective measure for mitigating methane emissions unless best management practices are instituted at composting facilities. Complementary evidence from airborne remote sensing imagery indicates atmospheric venting from refinery hydrogen plants, landfill working surfaces, composting stockpiles, etc., to be among the specific source types responsible for the observed discrepancies. This work highlights the value of multiple measurement approaches to accurately estimate facility-scale methane emissions and perform source attribution at subfacility scales to guide and verify effective mitigation policy and action.

Item Type:Article
Related URLs:
URLURL TypeDescription
Guha, Abhinav0000-0001-7748-1971
Newman, Sally0000-0003-0710-995X
Fairley, David0000-0002-1337-1463
Conley, Stephen C.0000-0001-6753-8962
Thorpe, Andrew K.0000-0001-7968-5433
Duren, Riley M.0000-0003-4723-5280
Cusworth, Daniel H.0000-0003-0158-977X
Foster, Kelsey T.0000-0002-2471-7319
Fischer, Marc L.0000-0001-7956-2361
Jeong, Seongeun0000-0003-2032-0127
Hanson, James L.0000-0002-8894-6532
Martien, Philip T.0000-0002-1751-998X
Additional Information:© 2020 American Chemical Society. Received: February 27, 2020; Revised: July 6, 2020; Accepted: July 7, 2020; Published: July 7, 2020. A majority of the Scientific Aviation (SA) flights have been sponsored by the Bay Area Air Quality Management District (BAAQMD) under contracts # 2016-106 and 2018-054. We appreciate Ian Faloona (University of California, Davis) for his management of contract # 2016-106, contributions to flight planning and discussions, and contract execution. We thank Guido Franco and California Energy Commission (CEC) for SA data collected under the Natural Gas Research Program (contracts # 500-12-006 and 500-13-005). Work at the Lawrence Berkeley National Laboratory was conducted under the US-DOE contract DE-AC02-36605CH11231. We thank California Air Resources Board (CARB) Research Division and Jorn Herner for data from SA flights. Data provided by California Polytechnic State University, San Luis Obispo researchers were obtained under CalRecycle contract DRR16109 and CARB contract ARB 16ISD006. AVIRIS-NG flights were funded by CARB, CEC, and NASA’s Earth Science Division as part of the California Methane Survey. We acknowledge the contributions and inputs of many BAAQMD staff members whose expertise has informed and advanced the flight planning, data analysis, and subsequent result interpretation. The statement and conclusions in this work are views and opinions of the authors and do not necessarily represent the views of the funding agencies. The authors declare no competing financial interest.
Funding AgencyGrant Number
Bay Area Air Quality Management District2016-106
Bay Area Air Quality Management District2018-054
California Energy Commission500-12-006
California Energy Commission500-13-005
Department of Energy (DOE)DE-AC02-36605CH11231
California Air Resources BoardARB 16ISD006
Issue or Number:15
Record Number:CaltechAUTHORS:20200707-131128451
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Official Citation:Assessment of Regional Methane Emission Inventories through Airborne Quantification in the San Francisco Bay Area. Abhinav Guha, Sally Newman, David Fairley, Tan M. Dinh, Linda Duca, Stephen C. Conley, Mackenzie L. Smith, Andrew K. Thorpe, Riley M. Duren, Daniel H. Cusworth, Kelsey T. Foster, Marc L. Fischer, Seongeun Jeong, Nazli Yesiller, James L. Hanson, and Philip T. Martien. Environmental Science & Technology 2020 54 (15), 9254-9264; DOI: 10.1021/acs.est.0c01212
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:104257
Deposited By: Tony Diaz
Deposited On:07 Jul 2020 21:07
Last Modified:16 Nov 2021 18:29

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