EPA repeals power plant greenhouse gas rule and proposes eliminating all remaining GHG standards

Overview

On September 14, 2026, the Environmental Protection Agency (EPA) announced two regulatory actions marking the latest chapter of the decade-plus effort to regulate greenhouse gas (GHG) emissions from the power sector under the Clean Air Act (CAA) (see our May 22, 2023 client update covering EPA’s GHG regulation history here).

• First, EPA issued a final rule (Final Rule) repealing most provisions of the so-called Carbon Pollution Standards promulgated by EPA in 2024 (2024 CPS). [1] These standards required existing fossil fuel-fired steam generating units and new fossil fuel-fired combustion turbines to cut GHG emissions, and implemented carbon capture and sequestration/storage (CCS) technology for certain new and existing power plants (see our May 29, 2024 client update here). The Final Rule, among other things, repeals these requirements. 
• Second, EPA proposed eliminating all remaining GHG standards for the power sector (Supplemental Proposal), which, if finalized, would effectively close the book on efforts to regulate GHG emissions from the power sector under the CAA entirely. [2]

Final Rule: Partial repeal of the 2024 Carbon Pollution Standards 

The Final Rule repeals most of the GHG standards promulgated in the 2024 CPS, including the standards based on the implementation of CCS, which the Final Rule concludes cannot be adopted in a manner consistent with the CAA. Under CAA Section 111, EPA is required to identify the best system of emission reduction (BSER) for each regulated source category, taking into account the cost of achieving such reduction, any non-air quality health and environmental impacts and energy requirements, and then to set emission standards based on the degree of emission reduction achievable through application of that system. The BSER identified in the 2024 CPS included the use of CCS beginning in 2032 for existing coal-fired steam generating units with the longest expected lifespans and for new base load combustion turbines. The Final Rule reverses those BSER determinations, including the selection of CCS. The Final Rule was published in the Federal Register on September 17, 2026, and is effective November 16, 2026. 

• What is repealed:
  • Emission guidelines for existing coal-fired steam generating units are repealed in their entirety, as follows:
    • For long-term units (defined as those expected to operate on or after January 1, 2039), EPA reverses its prior determination that 90% CCS is the BSER. EPA concludes that 90% CCS has not been “adequately demonstrated” (which, under the CAA, requires that the emission reduction system has been shown to work in practice, not just in theory). EPA notes that previous projects cited in the 2024 CPS as supporting its BSER determination, such as the Boundary Dam facility in Canada, failed to achieve 90% capture and were therefore not a sufficient basis to conclude the technology is viable at commercial scale. EPA further concludes that the costs of 90% CCS are not reasonable, that the associated degree of emission limitation is not achievable and that the necessary CO₂ capture, pipeline and sequestration infrastructure does not currently exist and is significantly unlikely to be deployable by the January 1, 2032 compliance date. 
    • For medium-term existing coal-fired units (defined as those that will operate on or after January 1, 2032 and plan to permanently cease operations before January 1, 2039), EPA reverses its prior determination that 40% natural gas co-firing is the BSER. EPA concludes that this would constitute an emission standard that forces a shift from one type of energy source to another, an example of “generation shifting” of the type that is impermissible under West Virginia v. EPA.[3] EPA further concludes that co-firing natural gas in a steam generating unit is an inefficient use of natural gas, and that the necessary pipeline infrastructure is unlikely to be available by the January 1, 2030 compliance date. 
  • Emission guidelines for existing natural gas- and oil-fired steam generating units are also repealed in their entirety.  The BSER for base load and intermediate load units under the 2024 CPS was routine methods of operation and maintenance, and the BSER for low load units was the use of uniform fuels, which would trigger the CAA Section 111(d) state plan process, which required each state to develop, submit and implement an enforceable plan for these sources. With the more significant coal-fired unit requirements now repealed, EPA concludes that requiring states to go through that entire regulatory process solely for natural gas- and oil-fired steam generating units would be an inefficient use of state resources, as these sources comprise a relatively small part of the source category and the emission guidelines would result in few or no emission reductions.
  • CCS-based standards for modified coal-fired units and new base load combustion turbines are also repealed. These include CCS-based standards for coal-fired steam generating units undertaking a large modification (i.e., a modification that increases the source’s hourly CO₂ emission rate by more than 10%), as well as the Phase II CCS-based standards for new base load stationary combustion turbines. EPA bases these repeals on similar grounds to those for the long-term coal-fired units, i.e., that 90% CCS has not been adequately demonstrated, the costs are unreasonable and the required infrastructure is unlikely to be available by the applicable compliance dates.
• What is retained: 
  • The Final Rule does not repeal certain aspects of the 2024 CPS, including the efficiency-based Phase I standards for new and reconstructed stationary combustion turbines, which remain in effect. These standards require lower-emitting fuels or highly efficient generating technology, depending on the subcategory, but do not require CCS or other add-on emission controls. EPA acknowledges commenters’ concerns regarding the achievability of these standards but declines to address them in the Final Rule, noting that the Supplemental Proposal, if finalized, would repeal all GHG standards, including these efficiency-based requirements.
  • Separately, the new source performance standards adopted in 2015 (2015 NSPS)[4] remain untouched by the Final Rule. These rules, promulgated by EPA under the Obama administration, include partial CCS-based and efficiency standards applicable to certain new, reconstructed and modified steam generating units and integrated gasification combined-cycle facilities. For new coal-fired power plants, the 2015 NSPS effectively require partial CCS. The 2015 NSPS have remained in place for over a decade notwithstanding intervening rulemakings in this area, including the rollback of GHG emissions regulations promulgated by EPA under the first Trump administration. However, if finalized, the Supplemental Proposal would repeal the 2015 NSPS as well.

Supplemental Proposal: Proposed repeal of all remaining power plant GHG standards

The Supplemental Proposal goes beyond the Final Rule by addressing a more fundamental question: whether Section 111 of the CAA authorizes EPA to regulate GHG emissions from fossil fuel-fired power plants to address global climate change at all.  Building on the rationale set forth in its February 2026 final rule rescinding the 2009 Endangerment Finding (Rescission Rule[5]) (discussed in our March 9, 2026 client update here), EPA proposes that it does not have such authorization. If finalized, the Supplemental Proposal would rescind the GHG-specific findings and determinations underlying the 2015 NSPS and would repeal all remaining GHG standards under Section 111, including the 2015 NSPS and the remaining standards for new and reconstructed stationary combustion turbines under the 2024 CPS. The proposed action is limited to regulation of GHGs to alleviate global climate change concerns and would not affect standards applicable to power plants for criteria pollutants, hazardous air pollutants and other emissions not based on global climate change concerns. Public comments on the Supplemental Proposal are due by November 2, 2026.

The noteworthy elements of the Supplemental Proposal are as follows:

• EPA’s proposed interpretation of Section 111. Section 111(b)(1)(A) directs EPA to list a category of stationary sources if, “in [the Administrator’s] judgment,” the category “causes, or contributes significantly to, air pollution which may reasonably be anticipated to endanger public health or welfare.” EPA now proposes that the “air pollution” contemplated by this provision is pollution that itself adversely affects public health or welfare through local or regional exposure. It is not pollution, such as global atmospheric concentrations of GHGs, whose asserted harms arise through global climate change. On that basis, EPA proposes that global climate change concerns do not provide a sufficient statutory predicate for regulating fossil fuel-fired power plant GHG emissions under Section 111. EPA reasons that the causal chain linking GHG emissions from a particular U.S. source category, changes in global atmospheric GHG concentrations, and resulting effects on public health and welfare is too “uncertain, conjectural, remote, and convoluted by intervening and confounding factors” to fit within the statute’s terms “cause,” “contribute” and “reasonably be anticipated to endanger.” Notably, this rationale is distinct from the primary proposal in EPA’s June 2025 proposed rule, which assumed that global climate change could constitute the relevant “air pollution” under Section 111, but proposed that fossil fuel-fired electric generating units do not “contribute significantly” to that pollution. 
• Extension of EPA’s Rescission Rule rationale. The Supplemental Proposal builds on the rationale underpinning the Rescission Rule, which concluded that Section 202(a)(1) of the CAA does not authorize EPA to regulate GHG emissions from motor vehicles to address global climate change. EPA now proposes to apply similar reasoning to power plants under Section 111. Relying in part on Loper Bright Enterprises v. Raimondo,[6] EPA argues that the relevant inquiry is the “best reading” of Section 111(b)(1)(A), rather than whether EPA’s prior interpretation was a permissible construction of ambiguous statutory language. EPA also proposes that the Rescission Rule “abrogates the legal foundation” of the alternative findings EPA made in 2015 that power plant GHG emissions contribute significantly to air pollution that endangers public health or welfare. In EPA’s view, those findings relied substantially on the interpretations and approach of the 2009 Endangerment Finding. Separately, EPA questions the regulatory foundation of the 2015 NSPS on the ground that EPA effectively created a combined fossil fuel-fired electric generating unit source category in 2015 without making a new source-category listing determination under Section 111(b)(1)(A).
• Major questions doctrine. EPA separately proposes that regulating GHG emissions from the U.S. power sector to address global climate change implicates the “major questions doctrine,” under which agencies must identify clear congressional authorization when asserting regulatory authority of vast economic and political significance. Relying principally on West Virginia v. EPA, EPA proposes that Congress did not clearly authorize the agency through Section 111 to regulate fossil fuel-fired power plants for this purpose. Unlike the Final Rule’s application of West Virginia to a particular BSER, the Supplemental Proposal questions whether Section 111 provides clear congressional authorization for this category of GHG regulation in the first place (a question not reached in West Virginia, which addressed only the permissibility of generation shifting as a “system of emission reduction”[7]. For background on the decision in West Virginia v. EPA, see our June 30, 2022 client update here).
• EPA’s climate-impact or “futility” rationale.  EPA also relies on modeling of the potential global climate effects of eliminating CO₂ emissions from the U.S. power sector. EPA modeled the complete elimination of CO₂ emissions from all new and existing U.S. fossil fuel-fired electric generating units and concluded that even this scenario would have no more than a de minimis effect on modeled global mean surface temperature and global sea-level rise. EPA argues that this analysis further supports its proposed interpretation of Section 111 and its alternative proposal that power plant GHG emissions do not “contribute significantly” to the relevant air pollution.

Key takeaways 

• Practical implications.
  • The Final Rule will take effect on November 16, 2026, at which point regulated entities will no longer be subject to the repealed CCS-based requirements and emission guidelines under the 2024 CPS, and states will be relieved of the associated Section 111(d) planning obligations. Although the compliance deadlines under the 2024 CPS were not immediate (January 1, 2032 for long-term coal-fired units and January 1, 2030 for medium-term units), the repeal removes the planning, permitting and capital investments that operators would need to undertake now to meet those deadlines. The Supplemental Proposal remains a proposal and, in the interim, the remaining Phase I efficiency-based standards and the 2015 NSPS continue to apply. These remaining standards largely reflect current industry practice, though the 2015 NSPS’s longstanding prohibition on new coal plants without partial CCS remains in effect and would only be lifted if the Supplemental Proposal is finalized.
  • These actions should be understood in the broader context of the Trump administration’s energy policy. Together with Executive Order 14261 (Reinvigorating America’s Beautiful Clean Coal Industry), rollbacks of the Inflation Reduction Act clean energy tax credits under the One Big Beautiful Bill Act of 2025, and the Rescission Rule, the Final Rule and Supplemental Proposal reflect a broader effort to remove federal regulatory barriers to coal- and natural gas-fired power generation. However, it remains unclear how these actions will affect coal-fired generation in practice, given the significant market forces reshaping the power sector independently of federal regulation. U.S. electricity demand is projected to reach record highs in 2027, driven in significant part by the rapid expansion of data centers and artificial intelligence.[8] Yet the market response to this surging demand appears to be centering on renewables, natural gas and nuclear rather than coal, with the U.S. Energy Information Administration projecting solar generation growing over 18% annually through 2027, while coal generation continues to decline.[9] Federal deregulation alone may prove insufficient to reverse the economic forces driving coal’s decline, including the declining cost of renewable energy, the limited pipeline of new coal projects, long lead times required for new coal capacity and the continued retirement of aging coal plants. Moreover, the prospect that a future administration could reimpose GHG standards creates its own form of regulatory uncertainty, potentially deterring the long-term capital commitments that new coal-fired capacity requires.
• Legal challenges.   
  • The first challenge to the Final Rule has already been filed. On September 17, 2026, a coalition of environmental and public health groups petitioned the D.C. Circuit to overturn the Final Rule.[10] The petitioners have publicly stated that the 2024 CPS are consistent with the Supreme Court’s decision in West Virginia v. EPA because they are based on pollution controls that can be implemented at individual plants, rather than the generation-shifting approach addressed by the Court.[11] On October 1, 2026, a New York-led coalition of states and municipalities filed a separate petition challenging the Final Rule.[12]
  • These challenges to the Final Rule are proceeding in parallel with the legal challenges pending against the Rescission Rule (see our March 9, 2026 client update here), which has drawn multiple challenges that have not yet reached substantive merits briefing. The outcomes of the Rescission Rule litigation may have significant implications for challenges to the Final Rule and the Supplemental Proposal, if finalized.
  • As with the Rescission Rule, litigation over the Final Rule could take significant time to resolve, and the Supplemental Proposal would likely be subject to separate legal challenges, if finalized. In the interim, it remains to be seen whether petitioners will seek a stay of the Final Rule pending judicial review.
• Impact on future regulation.
  • The stakes of these legal challenges are significant not just to the Final Rule, the Rescission Rule and the Supplemental Proposal (if finalized), but also to any future rulemaking in this field. Under Loper Bright, the authority to interpret the CAA generally lies with the courts rather than EPA. If reviewing courts were to resolve the scope of EPA’s authority under Section 111, including whether Section 111 authorizes regulation of power plant GHG emissions to address global climate change, those decisions would establish the legal ground rules for any future EPA rulemaking in this area. Thus, although the Final Rule and a finalized Supplemental Proposal would not themselves foreclose a future administration from taking yet another pass at GHG regulation of the power sector under the CAA, judicial decisions upholding EPA’s narrower interpretation of Section 111 could substantially constrain or potentially foreclose such efforts.