On Wednesday, June 11, 2025, the United States Environmental Protection Agency (EPA) issued a proposed rule that would repeal all greenhouse gas (GHG) emissions standards for fossil fuel-fired power plants. The proposed rule was published in the Federal Register on June 17, 2025. Specifically, the proposed rule would repeal the following New Source Performance Standards (NSPSs):
- NSPS Subpart TTTT, Standards of Performance for Greenhouse Gas Emissions for Electric Generating Units (EGUs)
- NSPS Subpart TTTTa, Standards of Performance for GHG Emissions for Modified Coal-Fired Steam EGUs and New Construction and Reconstruction Stationary Combustion Turbine EGUs
- NSPS Subpart UUUUb, Emission Guidelines for GHG Emissions for Electric Utility Generating Units
NSPS Subpart TTTTa requires all new and reconstructed stationary combustion turbine EGUs, operating as base load units, to meet emission standards equivalent to installing carbon capture and sequestration technology by January 1, 2032.
The proposed rule states that GHG emissions from fossil fuel-fired power plants do not contribute significantly to dangerous air pollution and that cost-effective GHG control measures, such as carbon capture and sequestration, are not reasonably available.
The EPA is also proposing to repeal the 2024 Final Action, which includes amendments to the National Emission Standard for Hazardous Air Pollutants (NESHAP) Subpart UUUUU, Mercury and Air Toxic Standards (MATS) Rule.
Review the Proposed Repeal of GHG Standards
Review the Proposed Repeal of MATS Amendments
SWCA Can Help
Please contact SWCA Environmental Consultant’s air quality experts to stay current with the development of these proposed rules, anticipated legal challenges, and how they could potentially affect the development or operation of your fossil fuel-fired power plant.
Bill [dot] Karl [at] swca [dot] com (Bill Karl) | Principal Air Quality Team Lead
bsohm [at] swca [dot] com (Brad Sohm) | Air Quality Director