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EPA Signs New Rule Affecting Air Emissions from Stationary Combustion Turbines

Thomas Dunder | February 18, 2020

On January 31, 2020, EPA finalized the residual risk and technology review (RTR) of the National Emission Standards for Hazardous Air Pollutants (NESHAP) for Stationary Combustion Turbines. This is commonly referred to as the “Turbine MACT.” When evaluating potential applicability of the NESHAP, EPA identified approximately 800 units, of which approximately 300 will likely be subject to the standard. The rule has significant implications for emissions testing requirements at combustion turbines.

The Rule:

  • Removes the exemption from meeting the standards during periods of startup, shutdown, and malfunction (SSM), to be consistent with a 2008 court decision;
  • Finalizes an operational standard for periods of startup to minimize emissions;
  • Requires electronic submittal of performance tests and compliance reports through EPA’s Central Data Exchange (CDX) using the Compliance and Emissions Data Reporting Interface (CEDRI); and
  • Requires initial and annual performance testing for new or reconstructed stationary combustion turbines in the subcategories identified below. These turbines must meet a formaldehyde limit of 91 parts per billion by volume, dry basis (ppbvd) at 15% oxygen (91 ppbvd @ 15% O2).
Four Turbine Subcategories Require Performance Testing

  • Lean premix gas-fired*
  • Lean premix oil-fired
  • Diffusion flame gas-fired*
  • Diffusion flame oil-fired

*The requirements of the rule are currently under a stay of effectiveness for these subcategories.

The rule is effective on the date of publication in the Federal Register and the initial performance test must be completed within 180 days after publication in the Federal Register. Thereafter, all combustion turbines in the affected subcategories and installed or reconstructed after January 14, 2003 must demonstrate annually that formaldehyde emissions do not exceed 91 ppbvd @ 15% O2 , when operating at base load, as measured using FTIR spectroscopy (EPA Test Method 320 or ASTM Method D6348).

Demonstrating this measurement 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 in order to achieve the required detection limits. The majority of FTIR analyzers currently used in emissions testing do not have a sufficiently low detection limit for this application. TRC’s STAC/A2LA accredited emissions testing group has the appropriate instrumentation and extensive experience with EPA Test Method 320, including having conducted numerous ppb-level formaldehyde tests at gas turbines. We own and operate FTIR systems that can achieve the detection limits to demonstrate compliance with this new standard.

For more information, please contact Dr. Thomas Dunder at or visit 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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