In this action, the U.S. Environmental Protection Agency (EPA) is supplementing its proposal to repeal all greenhouse gas (GHG) emission standards for fossil fuel-fired electric generating units (EGUs) to effectuate the best reading of Clean Air Act (CAA) section 111. We propose that CAA section 111 does not authorize the EPA to regulate emissions from power plants in response to global climate change concerns. For the multiple and independent reasons described herein, this additional rationale would also require rescinding the Administrator's contrary findings and determinations in 2015 and repealing all associated 2015 and 2024 GHG standards for the fossil fuel-fired EGU source category. In a separate action published concurrently with this supplemental notice, the EPA is finalizing the repeal of certain 2024 GHG standards for the fossil fuel-fired EGU source category on distinct legal and technical grounds. We are not reopening that final rule. Nor are we soliciting further comment on those issues through this supplemental notice, except to the extent that commenters believe the final rule bears on the distinct questions of statutory authority addressed herein.

In this final rule, the U.S. Environmental Protection Agency (EPA) is repealing most provisions of the 2024 Carbon Pollution Standards for greenhouse gas (GHG) emissions from fossil fuel-fired electric generating units (EGUs) based on a reevaluation of the best system of emission reduction for the relevant subcategories. Specifically, the EPA is repealing the emission guidelines for existing fossil fuel-fired steam generating units, the carbon capture and sequestration/storage (CCS)-based standards for coal-fired steam generating units undertaking a large modification, and the CCS-based standards for new base load stationary combustion turbines (i.e., Phase 2 standards). In a separate action published concurrently with this final rule, the EPA is issuing a supplemental proposal soliciting comment on additional reasons to rescind all GHG emission requirements for fossil fuel-fired EGUs to effectuate the best reading of Clean Air Act (CAA) section 111 and ensure consistency with applicable principles of administrative law beyond those reasons on which the EPA solicited comment in the June 2025 notice of proposed rulemaking.