EPA Rolls Back 2024 Emission Standards for Coal-Fired Electric Generating Units

Last June, we blogged about EPA’s proposal to repeal revisions to the National Emission Standards for Hazardous Air Pollutants (NESHAPs) for coal-fired electric generating units (EGUs). 

Those revisions were made in May 2024.

Here’s an update, which should not come as a surprise: on Feb. 24, the Environmental Protection Agency (EPA) published a final rule that did in fact repeal the May 2024 NESHAPs for coal-fired EGUs, on the same bases that were proposed when we last blogged about this, specifically:

• EPA repealed the 2024 standard’s emission limit for filterable particulate matter (which was 0.10 pounds per million British thermal units or lbs/MMBtu) and will revert to a 0.30 lbs/MMBtu limit that was set in 2012.  EPA based this repeal on a finding that the cost-effectiveness value for the 2024 limit was not in line with its prior practice and that the emissions of non-mercury metals that follow the repeal pose little risk.

• EPA repealed the requirement that all coal-fired EGUs demonstrate compliance with their limits on emissions of particulate matter (PM) by using continuous emission monitors, and will instead allow compliance to be demonstrated with quarterly stack testing and continuous parametric monitoring in addition to continuous emission monitors; and

• EPA revised the 2024 standard’s limit on emissions of mercury from lignite-burning coal-fired EGUs, raising it from 1.2 pounds per trillion Btus to 4 pounds per trillion Btus, based on a finding that there is not sufficient data that all lignite burning units can achieve the lower limit. Note: There are no lignite-burning EGUs in or near Pennsylvania.

The repeal of the 2024 standard was made pursuant to several of Trump’s Executive Orders, including Executive Order 14154 (“Unleashing American Energy”), and an April 8, 2025, Proclamation titled “Regulatory Relief for Certain Stationary Sources to Promote American Energy.”

The higher emission limits that will result from the repeal of the 2024 standard are predicted to lead to increase power plants’ emissions of mercury by about 999 pounds per year and fine PM by about 770 tons per year in 2028 in the aggregate, compared to what they would have been allowed to emit under the 2024 standards. 

The repeal will also allow power plants to increase emissions of all particulate matter by about 2,070 tons per year, sulfur dioxide by about 290 tons per year, and oxides of nitrogen (NOx) by 283 tons per year, also in the aggregate and compared to what they would have been permitted to emit under the 2024 standards.