Environmental Protection Agency Administrator Michael Regan on Nov. 22 signed a proposed rule that proposes to lower NOx emissions from new, modified, and reconstructed stationary combustion turbines and stationary gas turbines based on a review of available control technologies for limiting emissions of criteria air pollutants.
The comment period for the proposed rule, “Review of New Source Performance Standards for Stationary Combustion Turbines and Stationary Gas Turbines,” will be 90 days, beginning on the date of publication of the Proposed Rule in the Federal Register.
The standards subject to revision for CTs are located in 40 CFR Subpart KKKK and were last revised on July 6, 2006.
The standards to be revised for stationary gas turbines are located in 40 CFR Subpart GG and were last revised on September 10, 1979. See EPA’s Federalism Slideshow for this regulatory review here.
EPA will provide redlines of the proposed revisions when it releases the docket for comment, likely upon publication of the Proposed Rule. The new regulation will be located in a new Subpart KKKKa.
Clean Air Act, Section 111(b)(1)(B) authorizes EPA to conduct a review of existing New Source Performance Standards at least every eight years. EPA may, “if appropriate, revise” the standards. EPA may decline review if “such review is not appropriate in light of readily available information on the efficacy.” EPA issued the Proposed Rule is response to a 2023 settlement agreement with environmental groups for missing the eight year statutory deadline.
The Proposed Rule makes revisions to existing standards. Revisions using Section 111(b)(1)(B) are effective “upon promulgation.” EPA states that it has discretion under this provision to add emissions limits for pollutants or emissions sources not currently regulated for the source category.
Rulemaking General Overview
The Proposed Rule pertains to the source category composed of stationary CTs with a design base load rating equal to or greater than 10.7 GJ/h (10 mm/Btu/h), based on the higher heating value of the fuel, that commence construction, modification, or reconstruction after the date of publication in the Federal Register.
A CT is defined as all equipment including but not limited to the CT, including a heat recovery system (e.g., HRSG) and duct burners and other subcomponents. Both simple cycle and combined cycle turbines are covered.
NOx emissions
In general, EPA proposes a best system of emission reduction (BSER) of combustion controls with the addition of post-combustion selective catalytic reduction (SCR) for CTs in the small, medium, and large subcategories. However, at smaller sizes and at lower operating levels, EPA proposes standards based on the use of combustion controls without SCR.
Best System of Emission Reduction Details
EPA is proposing that BSER may differ for some categories of modified sources as compared to new CTs. A table in the proposed rule includes all categories of new and modified CT subcategories. See pages 65-66. It provides all 12 subcategories of CT-type with corresponding nitrogen oxide (NOx) emissions standards and rates.
SO2 emissions
EPA proposes to maintain the burning of low-sulfur fuels as an effective control for sulfur dioxide (SO2) emissions. Subpart KKKKa will set low-sulfur fuels as BSER for new, modified, and reconstructed CTs (all heat inputs and utilization levels). These standards are identical to Subpart KKKK. EPA anticipates no additional SO2 emissions reductions as proposed.
CO and PM emissions
EPA proposes to defer consideration of the need for CO and PM standards until after the agency completes its National Emission Standards for Hazardous Air Pollutants (NESHAP) rulemaking.
