Stationary Gas and Combustion Turbines: New Source Performance Standards (NSPS)
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Rule Summary
Stationary combustion turbines are a type of internal combustion engine that is composed of three main sections. The first section, the compressor, draws air into the engine, pressurizes it, and feeds it to the combustion chamber. Fuel is mixed with the compressed air and the mixture is burned in the combustion chamber. The combustion produces a high temperature, high pressure gas stream that enters and expands through the final section, the turbine section. As hot combustion gas expands through the turbine section, it spins rotating blades which turn a shaft. The rotating blades both drive the compressor to draw more pressurized air into the combustion section and either spin a generator to produce electricity or a mechanical drive (e.g., a compressor).
The turbine exhaust gases are hot enough, several hundred degrees, to produce additional useful output. Combined cycle and combined heat and power units use heat recovery steam generators (HRSG) to produce steam from the thermal energy in the turbine exhaust. This steam can either be used to produce additional electricity or for direct heating applications.
The New Source Performance Standards (NSPS) for stationary combustion turbines are outlined in the Code of Federal Regulations under 40 CFR Part 60 Subparts GG and KKKK. Subpart GG covers turbine engines that commenced constructed after October 3, 1977 and before February 18, 2005. Subpart KKKK covers both the combustion turbine engine and any associated heat recovery steam generator for units that commenced construction after February 18, 2005. The key pollutants EPA regulates from these sources includes nitrogen oxides (NOx) and sulfur dioxide (SO2).
On November 22, 2024, the EPA proposed to strengthen limits on emissions of nitrogen oxides (NOx) from most new, modified, and reconstructed fossil fuel-fired stationary combustion turbines, reducing dangerous air pollution for nearby communities. The proposed New Source Performance Standards (NSPS) are based on the application of combustion controls and selective catalytic reduction (SCR), a cost-reasonable and widely used add-on control technology that limits emissions of NOx. In addition, EPA is proposing to maintain the current limits for sulfur dioxide (SO2), which is well-controlled in this sector based on the long-term required use of low-sulfur natural gas and distillate fuels.
Rule History
03/25/2025 - Reopening of Comment Period (Stationary Gas Turbines and Stationary Combustion Turbines, subparts GG, KKKK & KKKKa)
11/22/2024 - Proposed Rule (Stationary Gas Turbines and Stationary Combustion Turbines, subparts GG, KKKK & KKKKa)
08/29/2012 - Proposed Rule (pdf) (519 KB) (Stationary Gas Turbines and Stationary Combustion Turbines, subparts GG & KKKK)
03/20/2009 - Direct Final Rule (pdf) (157 KB)(Stationary Combustion Turbines, subpart KKKK)
07/06/2006 - Final Rule (pdf) (256 KB)(Stationary Combustion Turbines, subpart KKKK)
02/24/2006 - Proposed Rule (pdf) (143 KB) & 02/24/2006 - Direct Final Rule (pdf) (166 KB)(Stationary Gas Turbines, Subpart GG)
02/18/2005 - Proposed Rule (pdf) (199 KB)(Stationary Combustion Turbines, subpart KKKK)
07/08/2004 - Final Rule; amendments (pdf) (225 KB)(Stationary Gas Turbines, Subpart GG)
05/28/2003 - Withdrawal of Direct Final Rule (pdf) (125 KB)(Stationary Gas Turbines, Subpart GG)
04/14/2003 - Proposed Rule (pdf) (131 KB)& 04/14/2003 - Direct Final Rule (pdf) (181 KB)(Stationary Gas Turbines, Subpart GG)
11/05/1987 - Final Rule; correction (pdf) (15.2 MB)(Stationary Gas Turbines, Subpart GG)
01/27/1982 - Final Rule (pdf) (15.1 MB)(Stationary Gas Turbines, Subpart GG)
04/15/1981 - Proposed Rule (pdf) (13 MB)(Stationary Gas Turbines, Subpart GG)
09/10/1979 - Final Rule (pdf) (13.2 MB)(Stationary Gas Turbines, subpart GG)
10/03/1977 - Proposed Rule (pdf) (27.8 MB)(Stationary Gas Turbines, subpart GG)
Additional Resources
Economic Impact Analysis of the Stationary Combustion Turbines NSPS: Final Report (February 2006) (pdf) (14.2 MB)
Economic Impact Analysis of the Proposed Stationary Combustion Turbines NSPS: Final Report (February 2005) (pdf) (14.2 MB)
View the supporting documents in the docket folder to find additional related documents to the rules.
Related Rules
Stationary Combustion Turbines: National Emission Standards for Hazardous Air Pollutants (NESHAP)
Alternative Control Techniques Document: NOx Emissions from Stationary Gas Turbines