Sabin Center Submits Comment Letters on EPA’s Proposed Repeal of Power Plant GHG Emission Standards – Climate Law Blog

On June 17, 2025, EPA published a proposed rule to either repeal entirely, or significantly revise, a rule issued in 2024 which set performance standards for fossil fuel-fired power plants to limit their greenhouse gas (GHG) emissions. This week, the Sabin Center filed three comment letters opposing the proposal. First, the Sabin Center commented on EPA’s primary proposal to repeal all GHG emissions standards for power plants. Second, the Sabin Center commented on EPA’s alternative proposal to repeal certain technology determinations which inform the performance standards. Third, the Sabin Center commented on the harmful impacts of EPA’s proposal on cities. This blog post summarizes EPA’s regulation of GHG emissions from power plants, its proposed rule, and the Sabin Center’s three comment letters.

EPA’s 2024 Rule

Under section 111 of the Clean Air Act, EPA must establish standards of performance for certain categories of stationary sources that “cause[ ], or contribute[] significantly to, air pollution which may reasonably be anticipated to endanger public health or welfare.” Pursuant to this statutory authority, EPA has been regulating power plants’ GHG emissions since 2009. On May 9, 2024, EPA published a final rule (referred to here as the “2024 Rule”) updating the performance standards for certain fossil fuel-fired power plants to limit their GHG emissions.

To establish performance standards, EPA must determine the emissions reductions that are achievable using the “best system of emission reduction” (BSER) that has been “adequately demonstrated,” taking into account the cost of the reductions, non-air quality health and environmental impacts, and energy requirements. EPA then sets an emissions cap based on the emissions reductions that can be achieved through use of the BSER. Notably, however, regulated entities are not required to install the BSER; they can meet the emissions cap through other measures if they so choose.

In the 2024 Rule, EPA set new performance standards based on updated BSER determinations for different sub-categories of fossil fuel-fired power plants. A summary of the BSER for each sub-category can be found here. Immediately after being issued, the 2024 Rule was challenged by several states and industry groups in the U.S. Court of Appeals for the D.C. Circuit. One of the key issues in the litigation was whether EPA was right to determine that the BSER for certain coal- and natural gas-fired power plants was a carbon capture and storage (CCS) system that captures 90% of carbon dioxide (CO₂) emissions. The challengers argued that such a system was not “adequately demonstrated” or “achievable” but EPA and various intervenors in the case disagreed. The Sabin Center filed two amicus briefs in defense of the 2024 Rule in the litigation.

After President Trump took office, EPA advised the court of its plans to initiate a rulemaking to revise the 2024 Rule and requested that the case be held in abeyance. The court granted that request on April 25, 2025.

EPA’s 2025 Proposed Rule

The Proposed Rule issued by EPA in June contains two main proposals. First, EPA proposes to repeal all GHG emissions standards for fossil fuel-fired power plants based on EPA’s determination that “GHG emissions from fossil fuel-fired power plants do not contribute significantly to dangerous air pollution within the meaning” of the Clean Air Act. Alternatively, EPA proposes to “revise the BSER determinations” from the 2024 Rule which rely on CCS technology.

EPA accepted comments on the proposal through August 7, 2025 and has indicated that it intends to release a final rule by December 2025. More detail on EPA’s proposal and the Sabin Center’s point-by-point rebuttals is included below but, generally speaking, EPA’s Proposed Rule reflects an egregious misrepresentation of scientific evidence and pollution control technology, and an unreasonable and unjustified change in position since it issued the 2024 Rule a mere year ago.

Comment on EPA’s Proposal to Repeal All GHG Emissions Standards

The Sabin Center’s first letter focuses on the legal and scientific errors underpinning EPA’s determination that emissions from fossil fuel-fired power plants do not contribute significantly to air pollution that endangers public health and welfare. Contrary to EPA’s unjustified determinations in the Proposed Rule, the clear causal link between power plant GHG emissions and pervasive harms to human health and welfare is established by a large body of scientific evidence.

This comment letter makes two arguments in opposition to EPA’s proposal:

• EPA’s legal interpretation of the “cause or contribute” standard is inconsistent with the plain meaning of the statute. EPA has erred in interpreting the statute to require consideration of “policy issues” when determining whether emissions from a source category will cause or contribute to air pollution that may reasonable be anticipated to endanger public health and welfare. EPA’s obligation under the Clean Air Act is to make a purely scientific judgment regarding the effects of air pollution attributable to the source category.
• EPA’s factual determination on endangerment is directly refuted by a large body of scientific evidence demonstrating a clear causal link between the power sector’s GHG emissions and harms to human health and welfare. There is overwhelming scientific consensus that climate change is causing pervasive and widespread harm to public health and welfare, including within the United States, and the harms attributable to fossil fuel-fired power plants surpass any reasonable threshold of significance. EPA has an obligation to engage with the available scientific information and reach a rational determination on endangerment in light of that information.

In support of these arguments, the Sabin Center’s letter summarizes several scientific reports and studies, and which were also submitted to EPA.

Comment on EPA’s Proposal to Repeal Certain BSER Determinations

The second letter was submitted by the Sabin Center and seven CCS scientists and engineers. The letter focuses on EPA’s erroneous finding that CCS with a 90% CO₂ capture rate is not “adequately demonstrated” and, therefore, cannot form the BSER for certain coal- and natural gas-fired power plants.

Just a year ago, in the 2024 Rule, EPA appropriately concluded that the technologies required to implement CCS with a 90% capture rate are adequately demonstrated and achievable, as required by the Clean Air Act. The Sabin Center and CCS experts strongly agree with that prior finding. As explained in the comment letter:

• The Proposed Rule articulates a new legal standard for establishing that an emissions control system has been “adequately demonstrated” that is wholly unsupported by the text and purpose of the Clean Air Act and case law interpreting it. EPA’s new claim that technologies that require further “enhancements and development that would take significant time” are not adequately demonstrated is inconsistent with its own prior findings and those of the courts. The case law is clear that, given the “technology forcing” nature of the Clean Air Act, EPA can determine that a technology is adequately demonstrated even if it is not already routinely used in an industry and would require design improvements or operational advances before being widely implemented. The courts have further recognized that EPA can factor in the lead time afforded to regulated parties in deciding that the technology will be adequately available by the compliance date and have not imposed any limits on the amount of time EPA may allow.
• In any event, even applying EPA’s new, flawed standard, CCS with a 90% capture rate is adequately demonstrated. CCS technologies have been successfully implemented at scores of commercial facilities worldwide, which establish that CCS with 90% capture is feasible. While EPA is correct that CCS is not currently in routine use within the power sector, it is ready to go and can be implemented without further technological enhancements and development. Commercial guarantees for such systems are available from reputable technology vendors.
• CCS technology is readily scalable. Existing projects were intended to, and did, validate capture technology at scale. While EPA is correct that the projects did not consistently capture 90% of CO₂ on a facility-wide basis, that was by design and not due to any flaw in the technology. Now that it has been proven effective and reliable, the technology is being deployed on a larger scale, with several new projects in development, as discussed below.
• The claim in the Proposed Rule that the BSER from the 2024 Rule is not cost reasonable is based on flawed cost analysis. As found in the 2024 Rule, the current deployment of CCS technology has proven to be cost effective in achieving 90% reductions in CO₂ The experience gained from existing projects has already enabled further CCS cost reductions.

Comment on the Harmful Impacts of EPA’s Proposal on Cities

The third letter submitted by the Sabin Center, together with Climate Mayors and C40 Cities, offers local governments’ perspectives on the harmful impacts that cities would experience were EPA to adopt its proposal. The letter raises the following key points:

• GHG emissions from fossil fuel-fired power plants contribute significantly to costly and detrimental fiscal and public health impacts for cities across the United States. EPA’s proposed finding that GHG emissions from fossil fuel-fired power plants do not contribute significantly to dangerous air pollution undervalues the damaging and dangerous impacts of this pollution experienced in cities. Cities experience more intense flooding, storms and extreme heat as a result of GHG emissions from the U.S. power sector, along with corrosion or destruction of infrastructure and significant costs to adapt to a changing climate and respond to extreme weather events. Without EPA limits on GHG pollution from the power sector, these impacts and costs fall in significant part at the feet of local governments.
• EPA proposes that its interpretation of “contributes significantly” should be “based on the impact of the existing regulation,” which is inconsistent with the text of the Clean Air Act and the case law that interprets it. But even under its own proposal, EPA regulation of GHG emissions from fossil fuel-fired electric generating units would have a significant impact on cities across the country, who rely on robust federal regulation to bolster their own greenhouse gas mitigation and climate adaptation efforts. Cities not only experience outsized impacts from the power sector’s GHG emissions, they also lead the efforts necessary to adapt and mitigate those impacts. EPA regulation helps limit the power sector’s significant contribution to global climate change, lessening the cost to cities to adapt augmenting local mitigation efforts. Moreover, federal regulation of power sector emissions has the indirect effect of reducing emissions from the buildings and transportation sectors, which are the top two sources of GHG emissions in U.S. cities

Adoption of EPA’s Proposed Rule would be catastrophic for U.S. climate policy and would significantly impede our ability to achieve necessary GHG emissions reductions from the power sector to mitigate further climate damages.

Olivia Guarna is the Climate Justice Fellow at the Sabin Center for Climate Change Law at Columbia Law School.