APS Response to the EPA Methane Emissions Reduction Program

June 2, 2023

U.S. Environmental Protection Agency
1200 Pennsylvania Avenue NW
Washington, DC 20460

To Whom It May Concern:

The American Physical Society (APS) — the largest physics membership organization in the United States, representing more than 50,000 members — appreciates the opportunity to provide written feedback to the Environmental Protection Agency (EPA) concerning its Methane Emissions Reduction Program. This feedback is based on recommendations from the 2022 joint report by APS and Optica (formerly OSA) titled, “Monitoring Methane Emissions from Oil and Gas Operations”.

The APS-Optica report provides a technical assessment of the current state of monitoring US methane emissions from oil and gas operations, which account for roughly 30% of US anthropogenic methane emissions. The report concludes that the United States is not effectively monitoring methane emissions, identifies current gaps and makes recommendations to address them. The recommended measures for the federal government include:

• creating a national open database of methane monitoring observations;
• establishing a national methane model; and
• investing in critical research areas.

The report suggests that EPA’s Financial and Technical Assistance program should prioritize research and improvements to national methane emissions monitoring capabilities for the oil and gas industry. Here, we highlight three recommended actions that will improve the nation’s detection capabilities and strengthen its monitoring policies that will lead to a decrease in methane emissions:

1. Financial and Technical Assistance funds should be directed towards developing a national database of methane emissions observations open to the stakeholder community. A national database would allow scientists to improve existing emissions inventories, develop a national methane model, identify opportunities to close gaps in current observational networks, and support observing system simulation experiments. A national database will bolster near-term monitoring needs and will be crucial for achieving nearterm emissions reductions.
2. Financial and Technical Assistance funds should be directed towards developing a national methane forecast and hind-cast model. A national model could be used to project the benefits of emission mitigation measures on reducing methane concentrations, check the consistency of improved emissions databases, and detect (and ideally identify) the location and onset time of significant accidental methane releases or emergence of significant new anthropogenic methane emissions. This national model is a vital tool for near-term emissions monitoring needs and near-term emissions reductions.
3. Financial and Technical Assistance should be directed towards research in the following three critical areas to improve the technologies used to effectively monitor methane:
   • Improving high-resolution spectroscopic databases to support methane sensing. High-resolution spectroscopic databases enable accurate modeling of light transmission through the atmosphere. These models are used to evaluate data retrieved from in-situ and remote-sensing platforms across observing scales (e.g., ground-based, airborne and spaceborne platforms).
   • Improving the ability for remote sensing and in situ measurement of carbon isotopes and remote sensing of ethane. Source apportionment is a critical aspect to successfully identifying and mitigating fugitive methane emissions in oil and gas infrastructure. Carbon isotopes are regularly used to determine from where (or when) a sample originated, thus providing the ability to distinguish fossil-fuelderived methane from biologically produced methane. Similarly, ethane is a tracer for fossil-fuel-derived methane sources, where its abundance can range from a few percent to 30% of natural gas, but it is not emitted by biological species.
   • Improve the quantum efficiency of photodetectors that support methane LIDAR. Current LIDAR systems are often required to rely on low-efficiency detectors at methane sensing bands around 1.65 micrometers. Improving the efficiency of the photodetectors at these wavelengths would significantly improve effective LIDAR monitoring.

Taking the above actions will accelerate our ability to effectively monitor and reduce methane emissions from the oil and gas industry. If you have questions or would like to further discuss the APS-Optica joint report or its recommendations, please do not hesitate to contact APS Director of Government Affairs Mark Elsesser; 202.846.8121.

Thank you for your consideration.

Sincerely,
Robert Rosner
President, American Physical Society