By Michael J. Nasi, Ben Rhem, Cody Vaughn, and Ava Moran

On September 14, 2026, EPA Administrator Lee Zeldin signed two companion actions that together would unwind more than a decade of greenhouse gas (GHG) regulation of the power sector under Clean Air Act Section 111. The first is a final rule repealing most of the 2024 Carbon Pollution Standards — including the 90 percent carbon capture and sequestration (CCS) mandate for existing coal units and the CCS standards for new baseload gas turbines. The second is a supplemental proposal that goes considerably further, proposing that Section 111 never authorized EPA to regulate power plants in response to global climate change at all.

The two actions reflect the same strategy EPA used earlier this year when it rescinded the 2009 Endangerment Finding and repealed vehicle GHG standards: EPA is resolving these questions on the statutory authority the Clean Air Act confers rather than by debating climate science. For power generators and developers, the practical effect of the final rule is immediate — the compliance obligations that were driving retirement decisions and complicating new gas construction disappear on the rule’s effective date. What remains in place rides on the supplemental proposal, and its comment period is the last meaningful opportunity to shape the outcome. Both actions share Docket No. EPA-HQ-OAR-2025-0124.

The Final Rule: What Is Repealed and What Survives

The final rule repeals the 2024 Carbon Pollution Standards’ core compliance obligations for the power sector:

• The 90 percent CCS mandate and January 1, 2032, deadline for existing “long-term” coal-fired steam units;
• The 40 percent natural gas co-firing mandate and January 1, 2030, deadline for existing “medium-term” coal units (those that had committed to permanently cease operating before 2039);
• The requirements for existing gas- and oil-fired steam units; and
• The CCS-based standards for new baseload combustion turbines and for coal units undertaking a large modification.

This is a partial repeal. The efficiency-based “Phase 1” standards for new and reconstructed combustion turbines remain in effect, as do the 2015 New Source Performance Standards for new coal units and all criteria-pollutant standards for power plants. EPA acknowledged what it called “meritorious concerns” about whether the Phase 1 turbine standards are achievable but declined to act on them in this rule, addressing them instead through the supplemental proposal.

EPA rested the repeal on a record-based reevaluation of the “best system of emission reduction” (BSER), not on any conclusion about climate science. It found that 90 percent CCS has not been adequately demonstrated — no coal plant has achieved continuous, facility-wide capture at that level — and that the necessary capture, pipeline, and storage infrastructure cannot realistically be built on the rule’s timeline. It concluded that the Section 45Q tax credit does not make CCS cost-reasonable because the credit “does not eliminate costs; it simply transfers costs to the U.S. taxpayer.” And it determined that the 40 percent co-firing mandate is impermissible “generation shifting” under West Virginia v. EPA — as is any standard that leaves a source no realistic option but to retire.

EPA estimates the repeal will save the power sector roughly $95 to $160 billion in present-value compliance costs through 2047. One consequence for permitting: the repealed limits will no longer serve as the GHG “BACT floor” in PSD permitting, though permitting authorities retain discretion to require more.

The Supplemental Proposal: A Broader Theory of No Authority

The supplemental proposal is the more consequential action over the long run. EPA proposes that Section 111 does not authorize it to regulate power-plant emissions in response to global climate change, and offers three independent grounds, each of which it says would stand on its own:

Statutory interpretation. EPA reads “air pollution” in Section 111 to mean pollution that threatens health or welfare through local or regional exposure — not global climate change — based on the statute’s text, structure, and history and on decades of agency practice, reinforced by Loper Bright.

Major questions doctrine. Consistent with West Virginia v. EPA, EPA concludes that setting the nation’s climate policy is a question of vast economic and political significance that Congress did not clearly delegate through Section 111.

Futility. EPA calculates that eliminating all U.S. power-plant carbon dioxide would change global mean surface temperature by about 0.014 °C by 2050 and 0.035 °C by 2100 — characterizing the 2100 figure as below the range of measurability and as less than a quarter of ordinary year-to-year temperature variation. On that basis it concludes these emissions do not “contribute significantly” to air pollution.

Notably, Section 111 sets a higher bar than the vehicle provision EPA addressed earlier this year: it requires that a source category “contribute significantly” to dangerous air pollution — a stricter threshold than Section 202’s “contribute.” EPA also argues that the 2015 findings are independently defective and that its rescission of the 2009 Endangerment Finding removed a foundation those findings relied on. If finalized, the proposal would repeal the remaining Section 111 GHG standards for power plants in their entirety — including the Phase 1 turbine standards that survive the final rule.

Why It Matters

• Existing coal and lignite units. The federal GHG compliance obligations that were pressuring these units toward retirement are gone. Owners should revisit retirement and capital plans premised on the 2030 or 2032 deadlines; because no state plan and no federal plan were ever in place, there is no transition mechanism to unwind.
• New gas generation. The CCS obligation for new baseload turbines is eliminated, removing a significant cost and schedule risk for new capacity — including capacity serving data-center and other large-load growth. The Phase 1 efficiency standards still apply for now, and their fate rides on the supplemental proposal.
• Permitting. The repealed standards no longer set the GHG BACT floor for PSD permits.

What’s Next

The final rule takes effect 60 days after Federal Register publication, and petitions for review may be filed in the D.C. Circuit within 60 days of publication. Litigation is certain; the D.C. Circuit is already holding the challenge to the 2024 rule in abeyance following oral argument.

The supplemental proposal carries a 45-day public comment period, with a virtual public hearing shortly after publication. Because the proposal — not the final rule — is what would end Section 111 GHG regulation of power plants as a matter of authority, the comment period is where affected parties can shape both the outcome and the record on review.

For questions about how these actions affect your operations, retirement and development plans, permitting, or comment strategy, please contact Michael J. Nasi, Ben Rhem, Cody Vaughn, or Ava Moran.

The opinions expressed are those of the authors and do not necessarily reflect the views of the firm, its clients, or any of its or their respective affiliates. This article is for informational purposes only and does not constitute legal advice. For more information, please contact a member of the Environment & Natural Resources practice.

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