Powering Down: EPA Rolls Back Power Plant Greenhouse Gas Emissions Standards

By Christopher P. Colyer, Julie Peng, and Sukhmani K. Singh

On September 14, 2026, the U.S. Environmental Protection Agency (EPA) finalized a significant rollback of federal greenhouse gas (GHG) requirements for fossil-fuel-fired power plants, repealing most of the Carbon Pollution Standards adopted by the Biden Administration in 2024.¹ At the same time, EPA issued a supplemental proposal that would go further and eliminate the remaining GHG emission standards applicable to fossil-fuel-fired electric generating units (EGUs) under Section 111 of the Clean Air Act (CAA).²

EPA’s final rule repeals three principal components of the 2024 Carbon Pollution Standards. First, EPA repealed the emission guidelines for existing fossil-fuel-fired steam generating units, including requirements for certain coal-fired units based on 90 percent carbon capture and sequestration storage (CCS) or 40 percent natural gas co-firing. Second, EPA repealed CCS-based standards applicable to coal-fired steam generating units undergoing a large modification. Third, EPA repealed the Phase 2 CCS-based standards for new base-load stationary combustion turbines, which would have required compliance with a standard based on 90 percent CCS beginning in 2032. No replacement standards were issued.

EPA concluded that 90 percent CCS is not adequately demonstrated for these sources, that the necessary capture, pipeline, and sequestration infrastructure is unlikely to be deployed at sufficient scale by the applicable compliance deadlines, and that the associated costs are unreasonable. EPA also reversed its position on natural gas co-firing, interpreting West Virginia v. EPA³ to prohibit requiring coal-fired units to shift a substantial portion of their fuel use to natural gas because, in EPA’s view, such a requirement constitutes impermissible generation shifting.

The final rule does not, however, eliminate every GHG standard applicable to fossil-fuel-fired power plants. EPA left in place certain efficiency-based standards for new combustion turbines and stated that highly efficient generation remains an appropriate best system of emission reduction (BSER) for new base-load combustion turbines.

EPA’s supplemental proposal would go substantially further. EPA is proposing that CAA Section 111 does not authorize the Agency to regulate power-plant emissions in response to global climate-change concerns. If finalized, the proposal would rescind EPA’s prior findings supporting regulation of power-sector GHG emissions and repeal all remaining GHG standards for fossil-fuel-fired EGUs under Section 111, including standards that were not affected by the final partial repeal. EPA published the supplemental proposal on September 17, 2026, and comments are due November 2, 2026.

The proposal follows EPA’s February 2026 rescission of the 2009 GHG Endangerment Finding applicable to motor vehicles under CAA Section 202. EPA is now applying a similar statutory interpretation to Section 111, proposing that global climate-change concerns do not satisfy the statutory prerequisite that emissions contribute significantly to air pollution which may reasonably be anticipated to endanger public health or welfare.

Shortly after EPA issued these rules, environmental and public-health organizations, including the American Lung Association, Environmental Defense Fund, and Natural Resources Defense Council, petitioned the D.C. Circuit for review of EPA’s final partial repeal.⁴ The challengers contend, among other things, that the 2024 standards were consistent with West Virginia v. EPA because they relied on pollution-control measures that could be applied at individual power plants rather than the system-wide generation shifting addressed by the Supreme Court in that case.

Given these initial challenges, companies should keep in mind that a reversal of some or all of the rules is possible. EPA recognized few reliance interests at stake, citing the effective date of 2032 and the lack of comments on this issue. Nevertheless, companies that do have reliance interests, should document their decision making. Additionally, the rollback does not affect independent state requirements or cap-and-trade programs.