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Maasakkers JD, McDuffie EE, Sulprizio MP, Chen C, Schultz M, Brunelle L, Thrush R, Steller J, Sherry C, Jacob DJ, Jeong S, Irving B, Weitz M. A Gridded Inventory of Annual 2012-2018 U.S. Anthropogenic Methane Emissions. Environ Sci Technol 2023; 57:16276-16288. [PMID: 37857355 PMCID: PMC10620993 DOI: 10.1021/acs.est.3c05138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 09/04/2023] [Accepted: 09/07/2023] [Indexed: 10/21/2023]
Abstract
Nationally reported greenhouse gas inventories are a core component of the Paris Agreement's transparency framework. Comparisons with emission estimates derived from atmospheric observations help identify improvements to reduce uncertainties and increase the confidence in reported values. To facilitate comparisons over the contiguous United States, we present a 0.1° × 0.1° gridded inventory of annual 2012-2018 anthropogenic methane emissions, allocated to 26 individual source categories, with scale-dependent error estimates. Our inventory is consistent with the U.S. Environmental Protection Agency (EPA) Inventory of U.S. Greenhouse Gas Emissions and Sinks (GHGI), submitted to the United Nations in 2020. Total emissions and patterns (spatial/temporal) reflect the activity and emission factor data underlying the GHGI, including many updates relative to a previous gridded version of the GHGI that has been extensively compared with observations. These underlying data are not generally available in global gridded inventories, and comparison to EDGAR version 6 shows large spatial differences, particularly for the oil and gas sectors. We also find strong regional variability across all sources in annual 2012-2018 spatial trends, highlighting the importance of understanding regional- and facility-level activities. Our inventory represents the first time series of gridded GHGI methane emissions and enables robust comparisons of emissions and their trends with atmospheric observations.
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Affiliation(s)
| | - Erin E. McDuffie
- Climate
Change Division, Environmental Protection
Agency, Washington, District of Columbia 20004, United States
| | - Melissa P. Sulprizio
- School
of Engineering and Applied Sciences, Harvard
University, Cambridge, Massachusetts 02138, United States
| | - Candice Chen
- SRON
Netherlands Institute for Space Research, Leiden 3584 CA, Netherlands
- School
of Engineering and Applied Sciences, Harvard
University, Cambridge, Massachusetts 02138, United States
| | - Maggie Schultz
- SRON
Netherlands Institute for Space Research, Leiden 3584 CA, Netherlands
| | - Lily Brunelle
- SRON
Netherlands Institute for Space Research, Leiden 3584 CA, Netherlands
| | - Ryan Thrush
- SRON
Netherlands Institute for Space Research, Leiden 3584 CA, Netherlands
| | - John Steller
- Climate
Change Division, Environmental Protection
Agency, Washington, District of Columbia 20004, United States
| | - Christopher Sherry
- Climate
Change Division, Environmental Protection
Agency, Washington, District of Columbia 20004, United States
| | - Daniel J. Jacob
- School
of Engineering and Applied Sciences, Harvard
University, Cambridge, Massachusetts 02138, United States
| | - Seongeun Jeong
- Lawrence
Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Bill Irving
- Climate
Change Division, Environmental Protection
Agency, Washington, District of Columbia 20004, United States
| | - Melissa Weitz
- Climate
Change Division, Environmental Protection
Agency, Washington, District of Columbia 20004, United States
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2
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Pollack IB, McCabe ME, Caulton DR, Fischer EV. Enhancements in Ammonia and Methane from Agricultural Sources in the Northeastern Colorado Front Range Using Observations from a Small Research Aircraft. Environ Sci Technol 2022; 56:2236-2247. [PMID: 35076215 DOI: 10.1021/acs.est.1c07382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Quantifying ammonia (NH3) to methane (CH4) enhancement ratios from agricultural sources is important for understanding air pollution and nitrogen deposition. The northeastern Colorado Front Range is home to concentrated animal feeding operations (CAFOs) that produce large emissions of NH3 and CH4. Isolating enhancements of NH3 and CH4 in this region due to agriculture is complicated because CAFOs are often located within regions of oil and natural gas (O&NG) extraction that are a major source of CH4 and other alkanes. Here, we utilize a small research aircraft to collect in situ 1 Hz measurements of gas-phase NH3, CH4, and ethane (C2H6) downwind of CAFOs during three flights conducted in November 2019. Enhancements in NH3 and CH4 are distinguishable up to 10 km downwind of CAFOs with the most concentrated portions of the plumes typically below 0.25 km AGL. We demonstrate that NH3 and C2H6 can be jointly used to separate near-source enhancements in CH4 from agriculture and O&NG. Molar enhancement ratios of NH3 to CH4 are quantified for individual CAFOs in this region, and they range from 0.8 to 2.7 ppbv ppbv-1. A multivariate regression model produces enhancement ratios and quantitative regional source contributions that are consistent with prior studies.
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Affiliation(s)
- Ilana B Pollack
- Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Megan E McCabe
- Department of Atmospheric Science, University of Wyoming, Laramie, Wyoming 82071, United States
| | - Dana R Caulton
- Department of Atmospheric Science, University of Wyoming, Laramie, Wyoming 82071, United States
| | - Emily V Fischer
- Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado 80523, United States
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3
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Gao J, Guan C, Zhang B. Why are methane emissions from China's oil & natural gas systems still unclear? A review of current bottom-up inventories. Sci Total Environ 2022; 807:151076. [PMID: 34678371 DOI: 10.1016/j.scitotenv.2021.151076] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 10/06/2021] [Accepted: 10/15/2021] [Indexed: 06/13/2023]
Abstract
There is growing awareness and concern on methane (CH4) emissions from China's oil and natural gas (ONG) systems owing to the carbon neutral target. This paper aims to present a comprehensive review on the bottom-up inventories of the CH4 emissions from the perspective of the ONG systems in China. The trend and magnitude of total emissions in the last four decades were revealed and limitations of current estimations were explored. Previous studies showed that the average CH4 emissions from China's ONG systems have almost tripled from 1980 (760 Gg) to 2015 (2180 Gg) with a trend of steady increase. However, the estimated values varied by an order-of-magnitude with the largest discrepancy of 2700 Gg. This discrepancy was unlikely caused mainly by the incompleteness of estimation, since dominant emission sources were all covered by representative studies. Moreover, the differences of activity-level data were within ±10%, which ruled out the possibility that it was the main contributor to the large discrepancies. The emissions estimate has huge variation in large part because of differences in assumed emission factors (EFs) that vary by an order of magnitude. The difficulty was to determine which of the EFs were accurate due to measurement-based data availability. Thus, the large discrepancies stem from the scarcity of publicly available data, which enlarged the impact from various methods adopted by previous studies. For better understanding of CH4 emissions from the ONG systems in China, the measurements of facility-level emissions and statistics on the ONG infrastructure are required urgently. Due to the high cost and experience-oriented measurement work, international cooperation and communications are critical prerequisites for future CH4 emission estimates and effective mitigation strategies.
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Affiliation(s)
- Junlian Gao
- School of Management, China University of Mining & Technology (Beijing), Beijing 100083, PR China
| | - ChengHe Guan
- New York University Shanghai, Shanghai 200122, PR China; Harvard China Project, School of Engineering and Applied Sciences, Harvard University, MA 02138, United States
| | - Bo Zhang
- School of Management, China University of Mining & Technology (Beijing), Beijing 100083, PR China; Harvard China Project, School of Engineering and Applied Sciences, Harvard University, MA 02138, United States; State Key Laboratory of Coal Resources and Safe Mining, China University of Mining & Technology (Beijing), Beijing 100083, PR China.
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4
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Nesme N, Marion R, Lezeaux O, Doz S, Camy-peyret C, Foucher P. Joint Use of in-Scene Background Radiance Estimation and Optimal Estimation Methods for Quantifying Methane Emissions Using PRISMA Hyperspectral Satellite Data: Application to the Korpezhe Industrial Site. Remote Sensing 2021; 13:4992. [DOI: 10.3390/rs13244992] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Methane (CH4) is one of the most contributing anthropogenic greenhouse gases (GHGs) in terms of global warming. Industry is one of the largest anthropogenic sources of methane, which are currently only roughly estimated. New satellite hyperspectral imagers, such as PRISMA, open up daily temporal monitoring of industrial methane sources at a spatial resolution of 30 m. Here, we developed the Characterization of Effluents Leakages in Industrial Environment (CELINE) code to inverse images of the Korpezhe industrial site. In this code, the in-Scene Background Radiance (ISBR) method was combined with a standard Optimal Estimation (OE) approach. The ISBR-OE method avoids the use of a complete and time-consuming radiative transfer model. The ISBR-OEM developed here overcomes the underestimation issues of the linear method (LM) used in the literature for high concentration plumes and controls a posteriori uncertainty. For the Korpezhe site, using the ISBR-OEM instead of the LM -retrieved CH4 concentration map led to a bias correction on CH4 mass from 4 to 16% depending on the source strength. The most important CH4 source has an estimated flow rate ranging from 0.36 ± 0.3 kg·s−1 to 4 ± 1.76 kg·s−1 on nine dates. These local and variable sources contribute to the CH4 budget and can better constrain climate change models.
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5
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Varon DJ, Jacob DJ, Jervis D, McKeever J. Quantifying Time-Averaged Methane Emissions from Individual Coal Mine Vents with GHGSat-D Satellite Observations. Environ Sci Technol 2020; 54:10246-10253. [PMID: 32672947 DOI: 10.1021/acs.est.0c01213] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Satellite observations of atmospheric methane plumes offer a means for global mapping of methane point sources. Here we use the GHGSat-D satellite instrument with 50 m effective spatial resolution and 9-18% single-pass column precision to quantify mean source rates for three coal mine vents (San Juan, United States; Appin, Australia; and Bulianta, China) over a two-year period (2016-2018). This involves averaging wind-rotated observations from 14 to 24 overpasses to achieve satisfactory signal-to-noise. Our wind rotation method optimizes the wind direction information for individual plumes to account for error in meteorological databases. We derive source rates from the time-averaged plumes using integrated mass enhancement (IME) and cross-sectional flux (CSF) methods calibrated with large eddy simulations. We find time-averaged source rates ranging from 2320 to 5850 kg h-1 for the three coal mine vents, with 40-45% precision (1σ), and generally consistent with previous estimates. The IME and CSF methods agree within 15%. Our results demonstrate the potential of space-based monitoring for annual reporting of methane emissions from point sources and suggest that future satellite instruments with similar pixel resolution but better precision should be able to constrain a wide range of point sources.
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Affiliation(s)
- Daniel J Varon
- Harvard University, Cambridge, Massachusetts 02138, United States
- GHGSat Inc., Montréal, Québec H2W 1Y5, Canada
| | - Daniel J Jacob
- Harvard University, Cambridge, Massachusetts 02138, United States
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6
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Gorchov Negron AM, Kort EA, Conley SA, Smith ML. Airborne Assessment of Methane Emissions from Offshore Platforms in the U.S. Gulf of Mexico. Environ Sci Technol 2020; 54:5112-5120. [PMID: 32281379 DOI: 10.1021/acs.est.0c00179] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Methane (CH4) emissions from oil and gas activities are large and poorly quantified, with onshore studies showing systematic inventory underestimates. We present aircraft measurements of CH4 emissions from offshore oil and gas platforms collected over the U.S. Gulf of Mexico in January 2018. Flights sampled individual facilities as well as regions of 5-70 facilities. We combine facility-level samples, production data, and inventory estimates to generate an aerial measurement-based inventory of CH4 emissions for the U.S. Gulf of Mexico. We compare our inventory and the Environmental Protection Agency Greenhouse Gas Inventory (GHGI) with regional airborne estimates. The new inventory and regional airborne estimates are consistent with the GHGI in deep water but appear higher for shallow water. For the full U.S. Gulf of Mexico our inventory estimates total emissions of 0.53 Tg CH4/yr [0.40-0.71 Tg CH4/yr, 95% CI] and corresponds to a loss rate of 2.9% [2.2-3.8%] of natural gas production. Our estimate is a factor of 2 higher than the GHGI updated with 2018 platform counts. We attribute this disagreement to incomplete platform counts and emission factors that both underestimate emissions for shallow water platforms and do not account for disproportionately high emissions from large shallow water facilities.
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Affiliation(s)
- Alan M Gorchov Negron
- Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Eric A Kort
- Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
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7
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Zhang Y, Gautam R, Pandey S, Omara M, Maasakkers JD, Sadavarte P, Lyon D, Nesser H, Sulprizio MP, Varon DJ, Zhang R, Houweling S, Zavala-Araiza D, Alvarez RA, Lorente A, Hamburg SP, Aben I, Jacob DJ. Quantifying methane emissions from the largest oil-producing basin in the United States from space. Sci Adv 2020; 6:eaaz5120. [PMID: 32494644 PMCID: PMC7176423 DOI: 10.1126/sciadv.aaz5120] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 03/19/2020] [Indexed: 05/26/2023]
Abstract
Using new satellite observations and atmospheric inverse modeling, we report methane emissions from the Permian Basin, which is among the world's most prolific oil-producing regions and accounts for >30% of total U.S. oil production. Based on satellite measurements from May 2018 to March 2019, Permian methane emissions from oil and natural gas production are estimated to be 2.7 ± 0.5 Tg a-1, representing the largest methane flux ever reported from a U.S. oil/gas-producing region and are more than two times higher than bottom-up inventory-based estimates. This magnitude of emissions is 3.7% of the gross gas extracted in the Permian, i.e., ~60% higher than the national average leakage rate. The high methane leakage rate is likely contributed by extensive venting and flaring, resulting from insufficient infrastructure to process and transport natural gas. This work demonstrates a high-resolution satellite data-based atmospheric inversion framework, providing a robust top-down analytical tool for quantifying and evaluating subregional methane emissions.
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Affiliation(s)
- Yuzhong Zhang
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
- Environmental Defense Fund, Washington, DC 20009, USA
- School of Engineering, Westlake University, Hangzhou, Zhejiang Province, China
- Institute of Advanced Technology, Westlake Institute for Advanced Study, Hangzhou, Zhejiang Province, China
| | - Ritesh Gautam
- Environmental Defense Fund, Washington, DC 20009, USA
| | - Sudhanshu Pandey
- SRON Netherlands Institute for Space Research, Utrecht, Netherlands
| | - Mark Omara
- Environmental Defense Fund, Washington, DC 20009, USA
| | | | - Pankaj Sadavarte
- SRON Netherlands Institute for Space Research, Utrecht, Netherlands
- TNO, Department of Climate, Air and Sustainability, Utrecht, Netherlands
| | - David Lyon
- Environmental Defense Fund, Washington, DC 20009, USA
| | - Hannah Nesser
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Melissa P. Sulprizio
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Daniel J. Varon
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Ruixiong Zhang
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
- ClimaCell Inc., 280 Summer Street Floor 8, Boston, MA 02210, USA
| | - Sander Houweling
- SRON Netherlands Institute for Space Research, Utrecht, Netherlands
- Department of Earth Sciences, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
| | - Daniel Zavala-Araiza
- Environmental Defense Fund, Washington, DC 20009, USA
- Institute for Marine and Atmospheric Research Utrecht (IMAU), Utrecht University, Utrecht, Netherlands
| | | | - Alba Lorente
- SRON Netherlands Institute for Space Research, Utrecht, Netherlands
| | | | - Ilse Aben
- SRON Netherlands Institute for Space Research, Utrecht, Netherlands
| | - Daniel J. Jacob
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
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8
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Saint-Vincent PMB, Pekney NJ. Beyond-the-Meter: Unaccounted Sources of Methane Emissions in the Natural Gas Distribution Sector. Environ Sci Technol 2020; 54:39-49. [PMID: 31809030 DOI: 10.1021/acs.est.9b04657] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The United States Environmental Protection Agency maintains an inventory of greenhouse gas emissions in accordance with the Intergovernmental Panel on Climate Change. Methane (CH4), a potent gas with a global warming potential 86-125× that of carbon dioxide (CO2) over a twenty-year period, is the main component of natural gas (NG). As NG becomes an increasingly larger percentage of the energy resources used in the United States, it is ever more important to evaluate the CH4 emissions inventory. However, the inventory also does not account for all possible sources of CH4 leaks, contributing to uncertainty in the national CH4 inventory. Discrepancies between top-down and bottom-up inventories of CH4 emissions imply that there are significant unaccounted-for sources of CH4 leaks, especially over cities. Diffuse CH4 plumes above cities that are not attributable to distribution pipelines or other NG infrastructure suggest many small beyond-the-meter leaks together contribute to large emissions. Here, we evaluate the distribution sector of the CH4 emissions inventory and make suggestions to improve the inventory by analyzing end-user emissions. Preliminary research into beyond-the-meter emissions suggests that while individually small, the appliances and buildings that make up the residential sector could contribute significantly to national scale emissions. Furnaces are the most leak-prone of appliances, contributing to 0.14% of total CH4 emissions from the NG sector in the United States. Combining measurements from whole house emissions and steady-state operation of appliances, we estimate that residential homes and appliances could release 9.1 Gg CH4 yearly in the United States, totaling over 2% of the CH4 released from the NG sector. While factors such as appliance age and usage, climate, and residential setting could influence the emissions profile of individual appliances, these preliminary estimates justify further exploration of beyond-the-meter emissions.
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Affiliation(s)
- Patricia M B Saint-Vincent
- Geologic and Environmental Systems Directorate, National Energy Technology Laboratory, Pittsburgh, Pennsylvania, United States
| | - Natalie J Pekney
- Geologic and Environmental Systems Directorate, National Energy Technology Laboratory, Pittsburgh, Pennsylvania, United States
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9
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Yu X, Millet DB, Wells KC, Griffis TJ, Chen X, Baker JM, Conley SA, Smith ML, Gvakharia A, Kort EA, Plant G, Wood JD. Top-Down Constraints on Methane Point Source Emissions From Animal Agriculture and Waste Based on New Airborne Measurements in the U.S. Upper Midwest. J Geophys Res Biogeosci 2020; 125:e2019JG005429. [PMID: 33614366 PMCID: PMC7894054 DOI: 10.1029/2019jg005429] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2019] [Accepted: 12/10/2019] [Indexed: 06/12/2023]
Abstract
Agriculture and waste are thought to account for half or more of the U.S. anthropogenic methane source. However, current bottom-up inventories contain inherent uncertainties from extrapolating limited in situ measurements to larger scales. Here, we employ new airborne methane measurements over the U.S. Corn Belt and Upper Midwest, among the most intensive agricultural regions in the world, to quantify emissions from an array of key agriculture and waste point sources. Nine of the largest concentrated animal feeding operations in the region and two sugar processing plants were measured, with multiple revisits during summer (August 2017), winter (January 2018), and spring (May-June 2018). We compare the top-down fluxes with state-of-science bottom-up estimates informed by U.S. Environmental Protection Agency methodology and site-level animal population and management practices. Top-down point source emissions are consistent with bottom-up estimates for beef concentrated animal feeding operations but moderately lower for dairies (by 37% on average) and significantly lower for sugar plants (by 80% on average). Swine facility results are more variable. The assumed bottom-up seasonality for manure methane emissions is not apparent in the aircraft measurements, which may be due to on-site management factors that are difficult to capture accurately in national-scale inventories. If not properly accounted for, such seasonal disparities could lead to source misattribution in top-down assessments of methane fluxes.
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Affiliation(s)
- Xueying Yu
- Department of Soil, Water, and Climate, University of Minnesota, Twin Cities, Saint Paul, MN, USA
| | - Dylan B Millet
- Department of Soil, Water, and Climate, University of Minnesota, Twin Cities, Saint Paul, MN, USA
| | - Kelley C Wells
- Department of Soil, Water, and Climate, University of Minnesota, Twin Cities, Saint Paul, MN, USA
| | - Timothy J Griffis
- Department of Soil, Water, and Climate, University of Minnesota, Twin Cities, Saint Paul, MN, USA
| | - Xin Chen
- Department of Soil, Water, and Climate, University of Minnesota, Twin Cities, Saint Paul, MN, USA
| | - John M Baker
- Department of Soil, Water, and Climate, University of Minnesota, Twin Cities, Saint Paul, MN, USA
- Agricultural Research Service, U.S. Department of Agriculture, St. Paul, MN, USA
| | | | | | - Alexander Gvakharia
- Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Eric A Kort
- Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Genevieve Plant
- Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Jeffrey D Wood
- School of Natural Resources, University of Missouri, Columbia, MO, USA
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10
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Forde ON, Cahill AG, Beckie RD, Mayer KU. Barometric-pumping controls fugitive gas emissions from a vadose zone natural gas release. Sci Rep 2019; 9:14080. [PMID: 31575969 DOI: 10.1038/s41598-019-50426-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 09/11/2019] [Indexed: 11/08/2022] Open
Abstract
Subsurface natural gas release from leaking oil and gas wells is a major environmental concern. Gas migration can cause aquifer contamination, explosive conditions in soil gas, and greenhouse gas emissions. Gas migration is controlled by complex interacting processes, thus constraining the distribution and magnitude of “fugitive gas” emissions remains a challenge. We simulated wellbore leakage in the vadose zone through a controlled release experiment and demonstrate that fugitive gas emissions can be directly influenced by barometric pressure changes. Decreases in barometric-pressure led to surface gas breakthroughs (>20-fold increase in <24 hours), even in the presence of low-permeability surficial soils. Current monitoring strategies do not consider the effect of barometric pressure changes on gas migration and may not provide adequate estimates of fugitive gas emissions. Frequent or continuous monitoring is needed to accurately detect and quantify fugitive gas emissions at oil and gas sites with a deep water table.
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11
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Plant G, Kort EA, Floerchinger C, Gvakharia A, Vimont I, Sweeney C. Large Fugitive Methane Emissions From Urban Centers Along the U.S. East Coast. Geophys Res Lett 2019; 46:8500-8507. [PMID: 31762518 PMCID: PMC6853254 DOI: 10.1029/2019gl082635] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 07/01/2019] [Accepted: 07/10/2019] [Indexed: 05/05/2023]
Abstract
Urban emissions remain an underexamined part of the methane budget. Here we present and interpret aircraft observations of six old and leak-prone major cities along the East Coast of the United States. We use direct observations of methane (CH4), carbon dioxide (CO2), carbon monoxide (CO), ethane (C2H6), and their correlations to quantify CH4 emissions and attribute to natural gas. We find the five largest cities emit 0.85 (0.63, 1.12) Tg CH4/year, of which 0.75 (0.49, 1.10) Tg CH4/year is attributed to natural gas. Our estimates, which include all thermogenic methane sources including end use, are more than twice that reported in the most recent gridded EPA inventory, which does not include end-use emissions. These results highlight that current urban inventory estimates of natural gas emissions are substantially low, either due to underestimates of leakage, lack of inclusion of end-use emissions, or some combination thereof.
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Affiliation(s)
- Genevieve Plant
- Department of Climate and Space Sciences and EngineeringUniversity of MichiganAnn ArborMIUSA
| | - Eric A. Kort
- Department of Climate and Space Sciences and EngineeringUniversity of MichiganAnn ArborMIUSA
| | | | - Alexander Gvakharia
- Department of Climate and Space Sciences and EngineeringUniversity of MichiganAnn ArborMIUSA
| | - Isaac Vimont
- Global Monitoring Division, Earth System Research LaboratoryNational Oceanic and Atmospheric AdministrationBoulderCOUSA
| | - Colm Sweeney
- Global Monitoring Division, Earth System Research LaboratoryNational Oceanic and Atmospheric AdministrationBoulderCOUSA
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12
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Zaimes GG, Littlefield JA, Augustine DJ, Cooney G, Schwietzke S, George FC, Lauderdale T, Skone TJ. Characterizing Regional Methane Emissions from Natural Gas Liquid Unloading. Environ Sci Technol 2019; 53:4619-4629. [PMID: 30924643 DOI: 10.1021/acs.est.8b05546] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
A "bottom-up" probabilistic model was developed using engineering first-principles to quantify annualized throughput normalized methane emissions (TNME) from natural gas liquid unloading activities for 18 basins in the United States in 2016. For each basin, six discrete liquid-unloading scenarios are considered, consisting of combinations of well types (conventional and unconventional) and liquid-unloading systems (nonplunger, manual plunger lift, and automatic plunger lift). Analysis reveals that methane emissions from liquids unloading are highly variable, with mean TNMEs ranging from 0.0093% to 0.38% across basins. Automatic plunger-lift systems are found to have significantly higher per-well methane emissions rates relative to manual plunger-lift or non-plunger systems and on average constitute 28% of annual methane emissions from liquids unloading over all basins despite representing only ∼0.43% of total natural gas well count. While previous work has advocated that operational malfunctions and abnormal process conditions explain the existence of super-emitters in the natural gas supply chain, this work finds that super-emitters can arise naturally due to variability in underlying component processes. Additionally, average cumulative methane emissions from liquids unloading, attributed to the natural gas supply chain, across all basins are ∼4.8 times higher than those inferred from the 2016 Greenhouse Gas Reporting Program (GHGRP). Our new model highlights the importance of technological disaggregation, uncertainty quantification, and regionalization in estimating episodic methane emissions from liquids unloading. These insights can help reconcile discrepancies between "top-down" (regional or atmospheric studies) and "bottom-up" (component or facility-level) studies.
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Affiliation(s)
- George G Zaimes
- National Energy Technology Laboratory , 626 Cochrans Mill Road , P.O. Box 10940, Pittsburgh , Pennsylvania 15236 , United States
| | - James A Littlefield
- National Energy Technology Laboratory , 626 Cochrans Mill Road , P.O. Box 10940, Pittsburgh , Pennsylvania 15236 , United States
| | - Daniel J Augustine
- National Energy Technology Laboratory , 626 Cochrans Mill Road , P.O. Box 10940, Pittsburgh , Pennsylvania 15236 , United States
| | - Gregory Cooney
- National Energy Technology Laboratory , 626 Cochrans Mill Road , P.O. Box 10940, Pittsburgh , Pennsylvania 15236 , United States
| | - Stefan Schwietzke
- NOAA Earth System Research Laboratory , 325 Broadway , Boulder , Colorado 80305 , United States
- Cooperative Institute for Research in Environmental Sciences , University of Colorado , 216 UCB , Boulder , Colorado 80309 , United States
| | - Fiji C George
- Cheniere Energy, Inc. , 700 Milam Street, Suite 1900 , Houston , Texas 77002 United States
| | - Terri Lauderdale
- AECOM , 9400 Amberglen Boulevard , Austin , Texas 78729 , United States
| | - Timothy J Skone
- National Energy Technology Laboratory , 626 Cochrans Mill Road , P.O. Box 10940, Pittsburgh , Pennsylvania 15236 , United States
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13
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Forde ON, Mayer KU, Hunkeler D. Identification, spatial extent and distribution of fugitive gas migration on the well pad scale. Sci Total Environ 2019; 652:356-366. [PMID: 30366336 DOI: 10.1016/j.scitotenv.2018.10.217] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 09/17/2018] [Accepted: 10/15/2018] [Indexed: 06/08/2023]
Abstract
Global methane (CH4) emissions are becoming increasingly important due to the contribution of CH4 to global warming. Leaking oil and gas wells can lead to subsurface CH4 gas migration (GM), which can cause both aquifer contamination and atmospheric emissions. Despite the need to identify and quantify GM at oil and gas well pads, effective and reliable monitoring techniques are lacking. In this field study, we used CH4 and carbon dioxide (CO2) efflux measurements together with soil gas stable carbon isotopic signatures to identify the occurrence and to characterize the spatio-temporal migration of fugitive gas across 17 selected well pads in Northeastern British Columbia, Canada. At 13 of these sites, operators had previously reported the occurrence of GM; however, subsequent inspections based on visual, olfactory or auditory evidence only identified GM at two of these sites. Using the soil gas efflux method, evidence for GM was found at 15 of the 17 well pads with CH4 and CO2 effluxes ranging from 0.017 to 180μmolm-2s-1(0.024 to 250gCH4m-2d-1) and 0.50 to 32μmolm-2s-1 (1.9 to 122gCO2m-2d-1), respectively. Stable carbon isotopic composition was assessed at 10 of the 17 well pads with 9 well pads showing evidence of GM. The isotopic values indicated that CH4 in soil gas was from the same origin as CH4 in the surface casing vent flow gas. There was no correlation between CH4 effluxes and the distance from the well head; an equal portion of elevated effluxes were detected >10m from the well head as were detected <5m from the well head. In addition, CH4 effluxes varied temporally with values changing by up to an order of magnitude over 2h. Although the study was carried out in Northeastern British Columbia, the results are applicable on a global scale, suggesting that inspections mostly based on visual evidence (e.g. bubbling at the well head) are not reliable for the identification of GM and, that infrequent survey measurements at predefined locations close to the well head may overestimate, underestimate or even miss CH4 effluxes. Repetitive and relatively densely spaced gas efflux measurements using a dynamic closed chamber method proved to be a useful tool for detecting GM.
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Affiliation(s)
- O N Forde
- Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, 2020-2007 Main Mall, Vancouver, BC V6T 1Z4, Canada.
| | - K U Mayer
- Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, 2020-2007 Main Mall, Vancouver, BC V6T 1Z4, Canada
| | - D Hunkeler
- Faculty of Sciences, Hydrogeology and Geothermal Center, University of Neuchatel, Neuchatel 2000, Switzerland
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14
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Omara M, Zimmerman N, Sullivan MR, Li X, Ellis A, Cesa R, Subramanian R, Presto AA, Robinson AL. Methane Emissions from Natural Gas Production Sites in the United States: Data Synthesis and National Estimate. Environ Sci Technol 2018; 52:12915-12925. [PMID: 30256618 DOI: 10.1021/acs.est.8b03535] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We used site-level methane (CH4) emissions data from over 1000 natural gas (NG) production sites in eight basins, including 92 new site-level CH4 measurements in the Uinta, northeastern Marcellus, and Denver-Julesburg basins, to investigate CH4 emissions characteristics and develop a new national CH4 emission estimate for the NG production sector. The distribution of site-level emissions is highly skewed, with the top 5% of sites accounting for 50% of cumulative emissions. High emitting sites are predominantly also high producing (>10 Mcfd). However, low NG production sites emit a larger fraction of their CH4 production. When combined with activity data, we predict that this creates substantial variability in the basin-level CH4 emissions which, as a fraction of basin-level CH4 production, range from 0.90% for the Appalachian and Greater Green River to >4.5% in the San Juan and San Joaquin. This suggests that much of the basin-level differences in production-normalized CH4 emissions reported by aircraft studies can be explained by differences in site size and distribution of site-level production rates. We estimate that NG production sites emit total CH4 emissions of 830 Mg/h (95% CI: 530-1200), 63% of which come from the sites producing <100 Mcfd that account for only 10% of total NG production. Our total CH4 emissions estimate is 2.3 times higher than the U.S. Environmental Protection Agency's estimate and likely attributable to the disproportionate influence of high emitting sites.
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Affiliation(s)
- Mark Omara
- Center for Atmospheric Particle Studies, Department of Mechanical Engineering , Carnegie Mellon University , 5000 Forbes Avenue , Pittsburgh , Pennsylvania 15213 , United States
| | - Naomi Zimmerman
- Center for Atmospheric Particle Studies, Department of Mechanical Engineering , Carnegie Mellon University , 5000 Forbes Avenue , Pittsburgh , Pennsylvania 15213 , United States
| | - Melissa R Sullivan
- Center for Atmospheric Particle Studies, Department of Mechanical Engineering , Carnegie Mellon University , 5000 Forbes Avenue , Pittsburgh , Pennsylvania 15213 , United States
| | - Xiang Li
- Center for Atmospheric Particle Studies, Department of Mechanical Engineering , Carnegie Mellon University , 5000 Forbes Avenue , Pittsburgh , Pennsylvania 15213 , United States
| | - Aja Ellis
- Center for Atmospheric Particle Studies, Department of Mechanical Engineering , Carnegie Mellon University , 5000 Forbes Avenue , Pittsburgh , Pennsylvania 15213 , United States
| | - Rebecca Cesa
- Center for Atmospheric Particle Studies, Department of Mechanical Engineering , Carnegie Mellon University , 5000 Forbes Avenue , Pittsburgh , Pennsylvania 15213 , United States
| | - R Subramanian
- Center for Atmospheric Particle Studies, Department of Mechanical Engineering , Carnegie Mellon University , 5000 Forbes Avenue , Pittsburgh , Pennsylvania 15213 , United States
| | - Albert A Presto
- Center for Atmospheric Particle Studies, Department of Mechanical Engineering , Carnegie Mellon University , 5000 Forbes Avenue , Pittsburgh , Pennsylvania 15213 , United States
| | - Allen L Robinson
- Center for Atmospheric Particle Studies, Department of Mechanical Engineering , Carnegie Mellon University , 5000 Forbes Avenue , Pittsburgh , Pennsylvania 15213 , United States
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15
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Alvarez RA, Zavala-Araiza D, Lyon DR, Allen DT, Barkley ZR, Brandt AR, Davis KJ, Herndon SC, Jacob DJ, Karion A, Kort EA, Lamb BK, Lauvaux T, Maasakkers JD, Marchese AJ, Omara M, Pacala SW, Peischl J, Robinson AL, Shepson PB, Sweeney C, Townsend-Small A, Wofsy SC, Hamburg SP. Assessment of methane emissions from the U.S. oil and gas supply chain. Science 2018; 361:186-188. [PMID: 29930092 DOI: 10.1126/science.aar7204] [Citation(s) in RCA: 147] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 05/18/2018] [Indexed: 11/02/2022]
Abstract
Methane emissions from the U.S. oil and natural gas supply chain were estimated by using ground-based, facility-scale measurements and validated with aircraft observations in areas accounting for ~30% of U.S. gas production. When scaled up nationally, our facility-based estimate of 2015 supply chain emissions is 13 ± 2 teragrams per year, equivalent to 2.3% of gross U.S. gas production. This value is ~60% higher than the U.S. Environmental Protection Agency inventory estimate, likely because existing inventory methods miss emissions released during abnormal operating conditions. Methane emissions of this magnitude, per unit of natural gas consumed, produce radiative forcing over a 20-year time horizon comparable to the CO2 from natural gas combustion. Substantial emission reductions are feasible through rapid detection of the root causes of high emissions and deployment of less failure-prone systems.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Anna Karion
- National Institute of Standards and Technology, Gaithersburg, MD, USA
| | | | | | - Thomas Lauvaux
- The Pennsylvania State University, University Park, PA, USA
| | | | | | - Mark Omara
- Environmental Defense Fund, Austin, TX, USA
| | | | - Jeff Peischl
- University of Colorado, CIRES, Boulder, CO, USA.,NOAA Earth System Research Laboratory, Boulder, CO, USA
| | | | | | - Colm Sweeney
- NOAA Earth System Research Laboratory, Boulder, CO, USA
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