Non-Satellite Methane Detection and Quantification Technologies

David Lyon, Ph.D.

Senior Methane Scientist II

Environmental Defense Fund

dlyon@edf.org

Today’s Presentation Outline

• Introduction
• How are leak detection and quantification technologies tested?
• Leak detection
• Direct measurements
• Vehicle-based measurements
• Drone-based measurements
• Aircraft-based measurements
• Stationary monitors
• Advice for using Non-satellite technologies
• Summary and Questions

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• Environmental Defense Fund (EDF) is a non-profit environmental advocacy organization.
• EDF is funded by our 3.5 million members and philanthropic donations.
• EDF employs ~1000 staff in 30 countries.
• EDF uses science and economics to find and implement effective solutions to environmental challenges including climate change, energy, human health, oceans, and ecosystems.

My Expertise in Oil and Gas Methane

• Ph.D. in Environmental Dynamics from University of Arkansas
• Dissertation on oil and gas methane super-emitters
• 2008 – 2012: Arkansas Department of Environmental Quality
• 2012 – 2022: Environmental Defense Fund
• 2023: United States Environmental Protection Agency
• 2024: University of Texas at Austin
• 2025 – present: Environmental Defense Fund
• Based in Colorado, United States

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Evaluating Leak Detection and Quantification Technologies

• Many technology companies claim their products can accurately detect or quantify small leaks but this is only true during ideal, laboratory-based conditions.
• Require technology companies to provide transparent data so you can evaluate their performance based on evidence not marketing.
• Independent evaluation with single-blind, controlled release testing using defined protocols in realistic conditions is the best data.
• Performance metrics include % true positive, % true negative, % false positive, % false negative, probability of detection, quantification accuracy
• https://metec.colostate.edu/aded-2-0/

Leak Detection and Quantification Technology Testing Facilities

https://metec.colostate.edu/

https://cstjf-pau.totalenergies.fr/en/our-expertise/leveraging-digital-innovation/tadi-test-center-international-reach-lacq

Leak Detection: Qualitative Surveys

• Audio, Visual, and Olfactory (AVO)
• Some natural gas leaks can be heard, seen, or smelled by human senses but this approach is unreliable and many leaks are missed by technicians.
• Hand-held concentration meters (U.S. EPA Method 21)
• Low-cost, high detection limit meters are used to measure CH₄ or hydrocarbon concentrations directly next to components.
• Leaks are indicated by concentrations above a defined threshold (e.g., 500 ppm).
• This approach is labor intensive and cannot detect inaccessible leaks.
• https://www.epa.gov/sites/default/files/2016-06/documents/m-21.pdf
• Hand-held laser-based meters
• Instruments that measure concentration along a path (ppm CH₄ m^-1) can be used by technicians to detect leaks or verify repairs from a longer distance than Method 21.
• https://metec.colostate.edu/handheld-laser/

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Leak Detection – Optical Gas Imaging

• Optical Gas Imaging (OGI) uses special infrared cameras and trained technicians to see methane and other hydrocarbons emissions normally invisible to the naked eye.
• Leak detection limits depend on environmental conditions and technician experience.
• https://pubs.acs.org/doi/full/10.1021/acs.est.0c01285
• Following survey protocols such as U.S. EPA Appendix K increases the likelihood of leak detection.
• https://www.ecfr.gov/current/title-40/chapter-I/subchapter-C/part-60/appendix-Appendix%20K%20to%20Part%2060

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Helicopter-based OGI survey of an unlit flare

Direct Measurements: Quantifying CH₄ Emission Rates

• Hand-held meters and correlation equations
• Similar to U.S. EPA Method 21, handheld meters measure methane or hydrocarbon concentration near components.
• A correlation equation is used to convert measured concentration (ppm CH₄) to an emission rate (gram CH₄ hour^-1).
• The correlation between concentration and emission rate usually is weak so this approach has low accuracy.
• https://ww2.arb.ca.gov/sites/default/files/2024-11/CH4LeakCorrelationsNGTransmission%26Storage_ada.pdf

www.mpowerinc.com/wp-content/uploads/2020/09/TA-Note-13-EPA-Method-21-LDAR-Using-NEO-PID-v.0.1.pdf

Direct Measurements

• Bagging
• If an emission source can be completely contained in a bag, then the CH₄ emission rate can be quantified by measuring the gas flow rate and gas composition.
• Acoustic meters
• Acoustic meters use sound to detect and quantify leaks but often have poor accuracy.
• Quantitative Optical Gas Imaging (QOGI)
• Some OGI cameras include software to quantify hydrocarbon emission rates but quantification can have high uncertainty.

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Direct Measurements

• High flow dilution sampler
• Portable instrument uses a vacuum to fully capture emissions from a leaking component and measures the outlet concentration and flow rate to estimate the methane emission rate.
• Cannot be used on inaccessible or very large emission sources.

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https://grist.org/energy/amy-townsend-small-study-methane-pecos-county-texas-abandoned-wells/

Vehicle-Based Measurements

• Basic Principle of Gaussian Dispersion Approaches
• Vehicles with high precision, fast response methane concentration analyzers and anemometers estimate site-level emission rates based on downwind methane concentration, wind speed and direction, and Gaussian dispersion equations.
• US EPA Other Test Method 33a
• Vehicle parks downwind of a site and measures methane concentration as the wind direction changes.
• https://www3.epa.gov/ttnemc01/prelim/otm33a.pdf
• Transect Approach
• Vehicle drives multiple transects downwind of site while measuring methane concentration.
• https://acp.copernicus.org/articles/18/15145/2018/

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Vehicle-Based Measurements: EPA OTM 33a

https://www3.epa.gov/ttnemc01/prelim/otm33a.pdf

Vehicle-Based Measurements

• Tracer Correlation
• A tracer gas (e.g., acetylene) is released at a known emission rate near the target methane emission source.
• A vehicle driving downwind transects measures the concentration of both the tracer gas and methane.
• The methane emission rate is estimated based on the ratio of the methane and tracer gas concentrations.
• This approach is highly accurate but can be complex to implement.

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https://www.sciencedirect.com/science/article/pii/S1537511023001496

Drone-Based Measurements

• Optical Gas Imaging
• An infrared camera mounted on a drone can be used for OGI surveys.
• Transect Approach
• Drone with methane concentration monitor flies downwind transects to estimate site- or equipment-level emissions.
• Curtain Approach
• Drone with methane concentration monitor flies a curtain (raster pattern perpendicular to wind direction) and measures the concentration across the plume to estimate site- or equipment-level emissions.

Drone-Based Measurements

https://seekops.com/technology/

https://totalenergies.com/projects/innovation-and-rd/ausea-innovative-technology-reducing-our-carbon-and-methane-emissions

Aircraft-Based Measurements

• Mass Balance
• Small aircraft with high precision, fast response methane concentration analyzer flies transects upwind and downwind of a target area or site. CH₄ concentration and wind data are used to estimate the methane emission rate from the area/site.

Aircraft-Based Measurements

• Passive Infrared Remote Sensing
• Infrared spectroscopy of reflected sunlight is used to image and quantify methane emission sources.
• This approach requires clear skies and has a relatively high detection limit (50% probability of detection ≈ 50 – 100 kg/hr CH₄).
• Aerial LiDAR
• Reflected laser light is measured to image and quantify methane emission sources.
• Aerial LiDAR has a much lower detection limit than other aircraft- and satellite-based technologies (50% probability of detection ≈ 1 kg/hr CH₄).

Aircraft-Based Passive IR Imaging

https://carbonmapper.org/

https://data.carbonmapper.org/?details=CH4_6A_500m_69.48368_41.09609%3Fstatus%3Dnot_deleted&plume_id=tan20260324t071822c67s4001-A#11.32/41.1098/69.5893

Aircraft-Based Gas Mapping LiDAR

https://www.bridgerphotonics.com/

Stationary Monitors

• Stationary monitors continuously collect methane concentration data but can only detect and quantify emissions when sensors are downwind of emission sources.
• Most stationary monitoring systems have relatively poor accuracy quantifying emissions but the technology is rapidly improving.
• https://pubs.acs.org/doi/full/10.1021/acsestair.4c00015
• Stationary monitors also can monitor operational data (e.g., gas pressure) that can inform emissions estimates including the duration of emission events observed with other technologies.

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Stationary Monitors

https://www.longpathtech.com/

https://pubs.acs.org/doi/full/10.1021/acs.estlett.4c00687

Advice for Measuring Methane

• Do not believe leak detection technology companies’ performance claims without transparent credible data that includes independent evaluation in the field or similar conditions.
• Be aware of the limitations of individual methods (e.g., some technologies require clear skies or temperatures above 0 C).
• Most technologies have detection limits that are probabilistic functions dependent on environmental conditions (e.g., 50% probability to detect a 1 kg CH4 h-1 leak in 3 m s-1 winds). Select methods with detection limits low enough to quantify most sources during the expected conditions.

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Advice for Measuring Methane

• Many emission sources are intermittent and may be missed by infrequent leak detection and quantification
• Aircraft-based LiDAR found 12 times higher methane emissions from Canadian well sites than OGI leak surveys.
• https://pubs.acs.org/doi/full/10.1021/acsestair.5c00195
• Conversely, observed emission sources may be shorter duration than assumed when extrapolating annual emissions.
• Integrating multiple measurements using different approaches and spatial and temporal scales is the most accurate approach for estimating methane emissions

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Questions?