On February 28, 2022, the U.S. Environmental Protection Agency (EPA) lifted a nearly two-decade long stay on formaldehyde air emissions limits for two types of stationary combustion turbines.

The turbines at issue, new lean premix gas-fired turbines and new diffusion flame gas-fired turbines, are primarily used in energy and chemical plants. Effective March 9, 2022, owners and operators will now have 180 days (September 5, 2022) to come into compliance with subpart YYYY of the National Emission Standards for Hazardous Air Pollutants (NESHAP) (40 CFR Part 63).

For now, EPA estimates there are roughly 250 turbines in use from the two impacted subcategories. These turbines will now have to comply with the formaldehyde emissions limit of 91 parts per billion. Compliance is demonstrated through initial and annual performance testing and continuous monitoring of applicable operating parameters.

EPA first issued the NESHAP for stationary combustion turbines in 2004, but stayed its effectiveness for the subcategories of lean premix and diffusion flame gas-fired turbines after industry groups petitioned to delist both subcategories.[1] EPA never finalized the delisting because in 2007, the D.C. Circuit ruled in NRDC v. EPA that EPA lacked the authority to delist subcategories of hazardous air pollutant sources. EPA revisited the NESHAP under the Trump Administration but left the stay in place to give the industry more time to comply and to consider a new petition to delist the full category of combustion turbines. Environmental groups then petitioned the agency to reconsider and threatened legal action if it did not lift the stay, leading to the current rule.

EPA’s decision to lift the stay while the underlying petition to delist the full category of combustion turbines from regulation under the NESHAP is not without controversy. Indeed, it represents a change in position by EPA, who previously sought to avoid imposing unnecessary compliance costs on the industry (as delisting would render the need to install pollution controls to address subpart YYYY requirements obsolete). In issuing this rulemaking, EPA asserted that it found no basis under the Clean Air Act or the Administrative Procedure Act to justify extending a regulatory stay simply because of the potential for a future change in law (i.e., future delisting of combustion turbines).

It is unclear whether EPA’s decision here signals the agency’s broader intent to implement other Clean Air Act regulations that have been stayed and held in abeyance. We are monitoring EPA’s actions and will report any developments.

[1] EPA did not stay the NESHAP for six other sub-categories of stationary combustion turbines which have been subject to the Subpart YYYY standard since 2004. This includes oil-fired lean premix and diffusion flame turbines, emergency turbines, turbines burning landfill or municipal waste, certain low-power turbines, and turbines operated on the North Slope of Alaska.