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Flaring & Fossil Fuels: Uncovering Emissions & Losses

Quantifying Undercounted O&G Emissions and Identifying Mitigation Opportunities

Fossil energy production, processing, flaring, and transmission all can harm climate and air quality by emitting greenhouse gases and air pollutants. It is critical to monitor emissions accurately to understand the impact of these activities on our environment.

Studies of onshore oil and gas production have shown that inventories significantly undercount methane emissions. Until recently, natural gas flares and offshore systems had not been the focus of quantification efforts.

Enter F³UEL: an innovative project to collect field measurements across all major U.S. flaring locations and offshore oil and gas sites, which resulted in the most extensive study of flares and offshore systems ever conducted. Spanning four years (2020-2023), F³UEL changed the worldwide perspective on flares by exposing unknown inefficiencies and similarly transformed the landscape of offshore oil and gas systems.

As a result, flares are a target for methane emission reductions in the Inflation Reduction Act, which has led to a $30 million Department of Energy (DOE) call for flare abatement technology development.

In addition, based on F³UEL data, the U.S. EPA has updated its inventory of offshore oil and gas emissions. The Bureau of Ocean Energy Management (BOEM) has been in contact with F³UEL researchers to understand and incorporate the study’s results into the planning of methane regulation implementation. The F³UEL team has also worked with satellite teams to help develop approaches to monitor offshore oil and gas systems from space and has conducted preliminary testing to demonstrate feasibility. 

The projects primary outputs may be summarized as follows:

  • Quantified methane and nitrogen oxide emissions from natural gas flares and offshore oil and gas production.
  • Provided insights to improve inventory accounting and identified mitigation opportunities.
  • Identified and began to evaluate methods for using satellite remote sensing products to monitor offshore emissions.
  • Enhanced public and scientific understanding of the environmental impacts of natural gas flaring and offshore energy production.
  • Engaged with stakeholders to inform management and policy.

All project data is available on U-M’s Deep Blue repository. As of February 2024, there have been more than 5,000 downloads of F3UEL datasets since the data was originally deposited. 

F³UEL employed in situ aircraft and satellite data, including both greenhouse gas and air quality measurements. To sample the largest regions of current and potential future offshore production and flaring, airborne measurements targeted the Gulf of Mexico, the Bakken Formation (North Dakota), the Permian and Eagle Ford Basins (Texas), as well as offshore California and Alaska.

Key findings are highlighted below. See journal articles, fact sheets, and media (right) for more details, and read about the Gulf of Mexico Offshore Emissions Pilot Study, which was the impetus for the F³UEL project.

F3UEL Project image

Key Findings

  • Both inefficient combustion and unlit flares contribute to substantial methane emissions that greatly exceed standard estimates for flaring.
  • Mitigation efforts that address either combustion efficiency or unlit flares (such as operational practices on flare maintenance), or reducing the usage of flares altogether (with alternatives such as re-injection or small-scale gas capture technology) would provide significant methane emission benefits.
  • DRE values are skewed. Destruction removal efficiency (DRE) characterizes how well a flare’s combustion destroys CH₄ in the waste gas. The majority of flares function close to expected performance, with DRE values near 98%. However, across all basins, a relatively modest number of poorly performing flares (with DRE values as low as 60%) were observed to cause a significant drop in average performance.
  • Unlit flares directly vent unburned gas to the atmosphere due to the flame being extinguished or never properly ignited, resulting in an additional impact on the flaring CH₄ budget. Given, based on observations, that ~3-5% of flares are unlit, the relative contribution of both poorly combusting and unlit flares to total CH₄ flaring emissions is similar.
  • Observed DRE combined with rate of unlit flares results in effective flare efficiencies that are considerably lower than the expected 98% across all three basins. The average observed DRE across the three regions of study is 95.2% and the average total effective DRE after accounting for unlit flares is 91.1%. These emissions estimates are ~5x larger than if assuming 98% DRE for all flares quantified by VIIRS and no occurrences of unlit flares (0.10 Tg CH₄/year). This indicates that flaring activities are a much larger part of the CH₄ O&G footprint than previously estimated.

  Inefficient and Unlit Natural Gas Flares Both Emit Large Quantities of Methane (Science, 2022)
  View/Download Fact Sheet (PDF)

  • A single NOx emission factor does not capture the range of observed emission factors in the Bakken, Permian, and Eagle Ford. All three basins show a heavy-tail distribution, with a minority of flares emitting the majority of NOx and a nontrivial number of flares producing NOx at least an order of magnitude larger than the EPA value. Bakken and Permian basin averages are 2X-3X the EPA value.
  • Extrapolation to basin scale emissions indicates that 20%–30% of flares are responsible for 80% of total basin-wide flaring NOx emissions.
  • Overall, NOx emissions from flaring vary widely depending on emission factors and gas composition, challenging the accuracy of bottom-up inventories.
  • Basin-specific emission factors and regional gas composition assumptions better capture average NOx flaring performance at the basin scale. However, a basin-specific approach may still miss high emitters in the heavy tail of skewed distributions.
  • It is crucial to count very high NOx-emitting flares in any air quality assessment in surrounding regions, as NOx has direct negative health impacts, such as asthma exacerbations.
  • Flaring for the studied region does not contribute significantly to the national NOx emissions estimate. However, flares account for a sizeable portion of NOx in O&G production and offer a potential opportunity for reduction.

  Excess Methane Emissions from Shallow Water Platforms Elevate the Carbon Intensity of US Gulf of Mexico Oil and Gas Production (PNAS, 2023)
  View/Download Fact Sheet (PDF)

  • The climate impact of offshore production in the U.S. is measured to be double that estimated in inventories (5.7 gCO2e/MJ compared to 2.4 gCO2e/MJ). This difference is primarily due to higher methane emission in Gulf of Mexico shallow waters.
  • Offshore U.S. oil and gas production has lower carbon intensity than onshore production.
  • Most production (80%) occurs in GOM deep waters, but most emissions (also 80%) occur outside of these areas.
  • Offshore carbon intensity varies greatly across the U.S. Gulf of Mexico deep waters show low climate impacts, while the Cook Inlet and Gulf of Mexico shallow waters have the largest carbon intensities.
  • The relative importance of CO2 and CH4 emissions differs between regions. For example, in GOM state shallow waters, CH4 emissions contribute significantly more to the carbon intensity than CO2 emissions, whereas CO2 is the dominant source of emissions in Alaska.

  Measurement-Based Carbon Intensity of U.S. Offshore Oil and Gas Production (Environmental Research Letters, 2024)
  View/Download Fact Sheet (PDF)

  • Observed methane emissions exceed inventories, elevating the carbon intensity of the basin to over twice the official inventories. Mean observed methane emissions in federal and state waters are 3X and 13X higher than inventories, respectively. Methane emissions are of particular concern because they have greater global warming potential than carbon dioxide, especially in the short term. They should be the first focus of mitigation efforts.
  • The carbon intensity of oil and gas production varies widely across the Gulf. Carbon intensity is extraordinarily high in shallow federal and state waters, where production rates are moderate and methane drives the majority of emissions. The observed shallow water carbon intensity far exceeds that of both deep water Gulf of Mexico production and typical global oil production. In contrast, carbon intensity is low in deep waters, where combustion emissions dominate the climate impact and production is high. Observational data of carbon dioxide from this study is generally consistent with inventories, suggesting that combustion is well-represented in the federal inventory.
  • Central hub processing facilities are the primary contributor to excessive shallow-water production emissions. High-emission events from these facilities are frequent and can be attributed to cold venting, emissions associated with tanks, and other pieces of equipment.

  In Situ Sampling of NOx Emissions from United States Natural Gas Flares Reveals Heavy-Tail Emission Characteristic (Environ. Sci. Technol., 2024)
  View/Download Fact Sheet (PDF)

  • By applying persistence and a newly defined metric, the chance of subsequent detection (CSD), the analysis of four years of repeated airborne sampling data from GOM central hubs reveals the sites that continue to emit methane over extended periods.
  • The average CSD for an emitting GOM central hub at any revisit time between one month and four years is 74%. The eight GOM central hubs with the largest emission rates (>750 kg/hr), greatly exceeding the EPA's super emitter threshold of 100 kg/hr, have an average CSD of 96%.
  • Forward-Looking Infrared (FLIR) camera imagery has shown cold venting at most of these super emitter sites, which—if it is the standard operating procedure—could explain these facilities’ high emissions and persistence. Modifying infrastructure to burn gas and maintain a consistent flame would support EPA goals and reduce the overall global warming potential of offshore production in the GOM.

  Temporal Variation and Persistence of Methane Emissions from Shallow Water–Oil and Gas Production in the Gulf of Mexico (Environ. Sci. Technol., 2024)
  Infographic (JPG)


Project Details and Contacts

  • Project period: 2020-2023
  • Funding: The project was funded by the Alfred P. Sloan Foundation with additional support from the Environmental Defense Fund, Scientific Aviation, and the University of Michigan.
  • Project lead: Eric Kort, College of Engineering, University of Michigan (PI) |

  • Eric Kort (PI), Climate and Space Sciences and Engineering, Applied Physics, University of Michigan
  • Ángel Adames-Corraliza, Atmospheric and Oceanic Sciences, University of Wisconsin-Madison
  • Maggie Allan, Graham Sustainability Institute, University of Michigan
  • Adam Brant, Department of Energy Resources Engineering, Stanford
  • Yulia Chen, Department of Energy Resources Engineering, Stanford
  • Steve Conley, Scientific Aviation
  • Catie Hausman, Ford School of Public Policy, University of Michigan
  • Alan Gorchov Negron, Climate and Space Sciences and Engineering, University of Michigan
  • Genevieve Plant, Climate and Space Sciences and Engineering, University of Michigan
  • Stefan Schwietzke, Climate & Energy Program, Environmental Defense Fund
  • Mackenzie Smith, Scientific Aviation
  • Daniel Zavala-Araiza, Climate & Energy Program, Environmental Defense Fund

A multi-sector advisory group provided input to improve the relevance of the work. Engagement with the Advisory Group ensured the research team had access to insights and additional considerations to improve the research plan and analyses of findings. and stakeholders had information and a clear understanding of offshore and flaring emissions necessary for improved decision-making around management and policy.

  • Colin Leyden, Environmental Defense Fund
  • David Picard, Clearstone Engineering
  • Cholena Ren, U.S. Bureau of Ocean Energy Management
  • Holli Wecht, U.S. Bureau of Ocean Energy Management
  • Melissa Weitz, U.S. Environmental Protection Agency

Past members: Christopher Konek, UN Environmental Programme