Assessment of methane emissions from the U.S. oil and gas supply chain

Alvarez, Ramón A.; Zavala-Araiza, Daniel; Lyon, David; Allen, David T.; Barkley, Z.; Brandt, Adam R.; Davis, Kenneth J.; Herndon, S. C.; Jacob, Daniel J.; Karion, A.; Kort, E. A.; Lamb, Brian; Lauvaux, Thomas; Maasakkers, Joannes D.; Marchese, Anthony J.; Omara, Mark; Pacala, Stephen W.; Peischl, J.; Robinson, Allen L.; Shepson, P. B.; Sweeney, Colm; Townsend‐Small, Amy; Wofsy, Steven C.; Hamburg, Steven P.

doi:10.1126/science.aar7204

Cited by 793 publications

(879 citation statements)

References 61 publications

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“…From the results of this study, we estimate emissions from UNG production and gathering facilities in SWPA to be equivalent to 0.5 ± 0.3% of production, in agreement with published top‐down emission estimates from northeast PA (0.36 ± 0.09%) and SWPA (0.0–3.5%) and site‐level measurements at well sites in northeast PA (0.44 ± 0.15%) and SWPA (0.57 ± 0.23%; Alvarez et al, ; Barkley et al, ; Omara et al, ; Ren et al, ). These emission rates as a percent of production are lower than rates found from top‐down studies performed in other gas basins, with the next lowest rate measured in the Haynesville shale at 1.3% (Alvarez et al, ; Karion et al, ; Peischl et al, ; Pétron et al, ; Schwietzke et al, ; Smith et al, ). The low fractional emission rates in this region are likely due to Marcellus wells having the highest production per well in the United States (Barkley et al, ; U.S. Energy Information Administration, ), requiring fewer components to produce large amounts of gas and thus lowering the potential for leaks (Brantley et al, ; Mitchell et al, ; Omara et al, ).…”

Section: Resultssupporting

confidence: 89%

“…Recent atmospheric studies measuring CH 4 emissions from natural gas activities ranging from component‐level (Zavala‐Araiza et al, ) to entire gas production basins (Barkley et al, ; Peischl et al, ; Pétron et al, ; Schwietzke et al, ; Smith et al, ) to continental‐scale inversions of emission inventories (Schwietzke et al, ) have shown large discrepancies between atmospheric and inventory‐based approaches. Emission estimates from this broad range of work systematically find that the EPA consistently underestimates CH 4 emissions from natural gas systems (Alvarez et al, ; Brandt et al, ; Zavala‐Araiza et al, ). One reason for this discrepancy may relate to the presence of high emitters responsible for a skewed distribution of CH 4 emissions along the supply chain (Brandt et al, ).…”

Section: Introductionmentioning

confidence: 98%

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Estimating Methane Emissions From Underground Coal and Natural Gas Production in Southwestern Pennsylvania

Barkley

Lauvaux

Davis

et al. 2019

Geophysical Research Letters

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Production of coal and natural gas is responsible for one third of anthropogenic methane (CH4) emissions in the United States. Here we examine CH4 emissions from coal and natural gas production in southwestern Pennsylvania. Using a top‐down methodology combining measurements of CH4 and ethane, we conclude that while Environmental Protection Agency inventories appear to report emissions from coal accurately, emissions from unconventional natural gas are underreported in the region by a factor of 5 (±3). However, production‐scaled CH4 emissions from unconventional gas production in the Marcellus remain small compared to other basins due to its large production per well. After normalizing emissions by energy produced, total greenhouse gas emissions from Pennsylvania unconventional natural gas production produce half the carbon footprint compared to regionally produced coal, with carbon dioxide emissions from combustion being the dominant source of greenhouse gas emissions for both sources.

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Section: Resultssupporting

confidence: 89%

Section: Introductionmentioning

confidence: 98%

Estimating Methane Emissions From Underground Coal and Natural Gas Production in Southwestern Pennsylvania

Barkley

Lauvaux

Davis

et al. 2019

Geophysical Research Letters

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“…Brandt et al (—see especially their Table S6) showed that in many U.S. gasfields and gas transmission and distribution systems, much of the mass of gas emitted comes from a few major leaks. Similarly, a recent synthesis of methane emissions from the oil and natural gas supply chain indicates that the most emissions come from production wells and that those are dominated by a few major sources (Alvarez et al, ). Mineral deposits provide a good analogy.…”

Section: Practical Emission Reduction and Removal—tractable Emissionsmentioning

confidence: 99%

Methane Mitigation: Methods to Reduce Emissions, on the Path to the Paris Agreement

Nisbet

Fisher

Lowry

et al. 2020

Reviews of Geophysics

235

131

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The atmospheric methane burden is increasing rapidly, contrary to pathways compatible with the goals of the 2015 United Nations Framework Convention on Climate Change Paris Agreement. Urgent action is required to bring methane back to a pathway more in line with the Paris goals. Emission reduction from “tractable” (easier to mitigate) anthropogenic sources such as the fossil fuel industries and landfills is being much facilitated by technical advances in the past decade, which have radically improved our ability to locate, identify, quantify, and reduce emissions. Measures to reduce emissions from “intractable” (harder to mitigate) anthropogenic sources such as agriculture and biomass burning have received less attention and are also becoming more feasible, including removal from elevated‐methane ambient air near to sources. The wider effort to use microbiological and dietary intervention to reduce emissions from cattle (and humans) is not addressed in detail in this essentially geophysical review. Though they cannot replace the need to reach “net‐zero” emissions of CO2, significant reductions in the methane burden will ease the timescales needed to reach required CO2 reduction targets for any particular future temperature limit. There is no single magic bullet, but implementation of a wide array of mitigation and emission reduction strategies could substantially cut the global methane burden, at a cost that is relatively low compared to the parallel and necessary measures to reduce CO2, and thereby reduce the atmospheric methane burden back toward pathways consistent with the goals of the Paris Agreement.

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“…The percentage is 1.9% if only production, gathering, and processing are included (Alvarez et al, ).…”

Section: Introductionmentioning

confidence: 99%

Methane Emissions from the Marcellus Shale in Southwestern Pennsylvania and Northern West Virginia Based on Airborne Measurements

et al. 2019

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Natural gas production in the United States has increased rapidly over the past decade, along with concerns about methane (CH4) fugitive emissions and its climate impacts. Quantification of CH4 emissions from oil and natural gas (O&NG) operations is important for establishing scientifically sound policies for mitigating greenhouse gases. We use the aircraft mass balance approach for three flight experiments in August and September 2015 to estimate CH4 emissions from O&NG operations over the southwestern Marcellus Shale. We estimate a mean CH4 emission rate as 21.2 kg/s with 28% coming from O&NG operations. The mean CH4 emission rate from O&NG operations was estimated to be 1.1% of total NG production. The individual best‐estimate emission rates from the three flight experiments ranged from 0.78 to 1.5%, with overall limits of 0% and 3.5%. These emission rates are at the low end of other top‐down studies, but consistent with the few observational studies in the Marcellus Shale region as well as the U.S. Environmental Protection Agency CH4 inventory. A substantial source of CH4 (~70% of observed CH4 emissions) was found to contain little ethane, possibly due to coalbed CH4 emitted either directly from coal mines or from wells drilled through coalbed layers in O&NG operations. Recent regulations requiring capture of gas from the completion‐venting step of hydraulic fracturing appear to have reduced the atmospheric release of CH4. Our study suggests that for a 20‐year time scale, energy derived from the combustion of natural gas extracted from this region likely exerts a net climate benefit compared to coal.

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Assessment of methane emissions from the U.S. oil and gas supply chain

Cited by 793 publications

References 61 publications

Estimating Methane Emissions From Underground Coal and Natural Gas Production in Southwestern Pennsylvania

Estimating Methane Emissions From Underground Coal and Natural Gas Production in Southwestern Pennsylvania

Methane Mitigation: Methods to Reduce Emissions, on the Path to the Paris Agreement

Methane Emissions from the Marcellus Shale in Southwestern Pennsylvania and Northern West Virginia Based on Airborne Measurements

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