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EPA Lifts Stay of Standards for New Lean Premix and Diffusion Flame Gas-fired Combustion Turbines

Thomas Dunder | March 14, 2022

On February 28, the EPA Administration signed a notice to finalize amendments to the National Emission Standards for Hazardous Air Pollutants (NESHAP) for Stationary Combustion Turbines. The final action removes the stay of the effectiveness of the standards for new lean premix and diffusion flame gas-fired turbines that was promulgated in 2004. “New” is defined in the rule to include units which started construction on or after January 1, 2003.

The NESHAP rule became effective on March 9, 2022, the date of publication in the Federal Register. Owners and operators have 180 calendar days after publication to demonstrate initial compliance with a formaldehyde emission limit of 91 parts per billion by volume, dry basis (ppbvd) at 15 percent oxygen (O2). Compliance demonstration is required annually thereafter. Importantly, formaldehyde must be measured using FTIR spectroscopy (EPA Test Method 320 or ASTM Method D6348).

Demonstrating compliance with this emission standard is challenging because it pushes the limits of FTIR technology, and testing must be conducted to identify and eliminate all sources of bias in sampling and analysis to achieve the required detection limits. The majority of traditional FTIR analyzers used in emissions testing are not able to achieve the low detection limit to support the compliance demonstration requirements of this standard. TRC’s STAC/A2LA accredited emissions testing group has the appropriate instrumentation and extensive experience with EPA Test Method 320. Importantly, TRC has supported EPRI research to establish requirements for formaldehyde sampling at compliance demonstration levels and has also conducted numerous ppb-level formaldehyde tests on gas turbines. Our FTIR systems can achieve the detection limits to demonstrate compliance with this new standard.

For additional information on the NESHAP for Stationary Combustion Turbines, please see my February 2020 Insights article on this topic.

For more information, please contact Dr. Thomas Dunder at or visit TRC Air Quality to find out more about the services TRC can offer.

Tom Dunder, Ph.D.

Tom Dunder is Technical Director in the Air Management Services Division at TRC Companies in Raleigh, North Carolina where he performs and manages air pollutant testing programs. He has degrees in Chemistry from Columbia (A.B.), Rutgers (M.S.) and the University of North Carolina (Ph.D.). Tom has 29 years of experience in gaseous pollutant emissions measurements at a wide variety of industries (refineries, chemical plants, power plants, paper mills, etc.) with recent work in biomass/biogas processes and emerging pollutants like PFAS. Contact Tom at

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