EPRI Technical Public Comments on U.S. EPA’s Draft New Social Costs of Carbon and Other Greenhouse Gases Estimation Methodology and Use of Estimates in EPA’s Proposed Oil and Gas Methane Rule

On November 11th 2022, the U.S. EPA released a proposed rule for regulating methane emissions from oil and gas operations (Standards of Performance for New, Reconstructed, and Modified Sources and Emissions Guidelines for Existing Sources: Oil and Natural Gas Sector Climate Review, Docket ID No. EPA–HQ–OAR–2021–0317). Along with the proposed rule, EPA introduced a draft new methodology for estimating the social costs of carbon and other greenhouse gases (SC-GHG).

The SC-GHGs are important metrics that are used in regulations and other federal decisions to assess policy proposals, justify actions, and set standards with significant financial and social implications. The U.S. Government SC-GHG estimates are also being considered by U.S. states and other countries. However, SC-GHG estimates are complex to calculate, requiring multi-century modeling of potential future global societies, climate change, sea level rise, and economic damages from climate change.

This publication represents the public comments EPRI submitted on February 13th, 2023, on EPA’s draft new SC-GHG methodology and use of SC-GHG estimates in the proposed rule. EPRI’s public comments are technical in nature and based on extensive EPRI SC-GHG related research and expertise covering SC-GHG estimation as well as application (i.e., use), including EPRI’s participation on the National Academies of Sciences, Engineering and Medicine (NASEM) Social Cost of Carbon committee, who’s recommendations EPA’s draft methodology was designed to address.

After thoroughly reviewing EPA’s draft new methodology, EPRI has found that the methodology and estimates are not yet scientifically reliable and robust for policy use. The methodology contains multiple significant technical issues and does not satisfy the NASEM recommendations. This should be addressed before the estimates are deployed to inform policy, for EPA’s methane rule and otherwise. In general, EPRI recommends an improved process, enhanced documentation, a revised methodology, and improved application of SC-GHGs. EPRI’s detailed comments include specific overall and module-specific and cross-module recommendations, as well as discussion of our technical observations that underpin each recommendation and insights that inform how to move forward.