The Environmental Protection Agency ("EPA") has announced a new proposed rule that would strengthen the National Emission Standards for Hazardous Air Pollutants ("NESHAP") for Coal- and Oil- Fired Electric Utility Steam Generating Units ("EGUs").
Earlier this week, the EPA proposed the most significant update to the NESHAP for Coal- and Oil- Fired EGUs, commonly known as the Mercury and Air Toxics Standards ("MATS") for power plants, since the MATS were first issued in February 2012. This proposal follows the February 2023 EPA announcement reaffirming the scientific, economic, and legal underpinnings of the 2012 MATS and revoking a 2020 finding that it was not appropriate and necessary to regulate coal- and oil-fired power plants under section 112 of the Clean Air Act. The proposed rule is intended to reflect significant improvements in pollution control technologies and satisfy the EPA's requirement to periodically review emissions standards.
EPA is proposing to reduce the non-mercury metal surrogate filterable particulate matter ("fPM") emission standard for all coal-fired EGUs to 1.0E-02 lb/MMBtu. EPA is further proposing that existing lignite-fired EGUs must meet the same mercury emission standard as EGUs firing other types of coal, such as bituminous and subbituminous, which is 1.2 lb/TBtu, or an alternative output-based standard of 1.3E-02 lb/GWh.
The proposed rule would also require that all coal-fired EGUs demonstrate compliance with the fPM emission standard by using PM continuous emission monitoring systems. This would result in the removal of the total and individual non-mercury metals emission limits from the MATS as well as the total and individual non-mercury hazardous air pollutant metals from the low-emitting EGU program.
In addition to comments on the current proposed revisions, EPA is specifically soliciting comment on potential future reduction of the MATS fPM emission standard to an even more stringent level of 6.0E-03 lb/MMBtu. The proposed rule will be open to public comment for 60 days after publication in the Federal Register, which is expected this month.
