EPA Corrects Small Errors in Turbine Emissions Standards
Published Date: 7/16/2026
Rule
Summary
The EPA fixed some small mistakes in the rules for stationary combustion and gas turbines that were first published in January 2026. These corrections make sure the rules are clear and accurate for companies that build or operate these turbines. The updated rules take effect on August 17, 2026, with no new costs or big changes—just clean, clear standards.
Analyzed Economic Effects
10 provisions identified: 10 benefits, 0 costs, 0 mixed.
Clarified gas turbine applicability
If you own or operate gas turbines, the rule text now clearly says a "gas turbine" (not a "combustion turbine") that is not a "major source" is exempt from the cited section. This correction takes effect on August 17, 2026 and aligns the regulatory text with Subpart GG.
Title II turbines excluded from Subpart KKKK
The rule text now explicitly says combustion turbines that are subject to Title II of the Clean Air Act are not covered by Subpart KKKK. This correction is effective August 17, 2026 and aligns the regulatory text with the intended coverage.
Optional temporary turbine subcategory clarified
Owners or operators of small- or medium-size stationary combustion turbines (base load rating ≤ 850 MMBtu/h) may elect to treat a unit as a temporary combustion turbine for up to 24 consecutive months as an alternative to otherwise applicable standards. This clarification is effective August 17, 2026.
Performance test interval extended to 14 months
For owners/operators subject to Subpart KKKKa, subsequent performance tests must be conducted within 14 calendar months of the previous test (not 12 months). This correction is effective August 17, 2026.
Fuel-records allowed for SO2 compliance
The corrected text clarifies that owners/operators may use fuel records (e.g., purchase contracts, tariff sheets, transportation contracts, or fuel analysis) to demonstrate compliance with the SO2 fuel-based standard, and adds an explicit reference to Sec. 60.4372a. This clarification is effective August 17, 2026.
Size threshold reverted to 30 MW
The rule reverts the size threshold for certain subcategories from a heat-input threshold of 300 MMBtu/h back to the prior output-based threshold of 30 MW. The Agency states this change has no practical effect because turbines >30 MW also exceed 300 MMBtu/h. The correction is effective August 17, 2026.
Performance-test load levels clarified (30% / 70%)
Performance tests (with or without CEMS) must be conducted at a load condition within 30 percent of 100 percent of the base load rating, and testing may be done at the highest achievable load point if at least 70 percent of the base load rating cannot be achieved. This correction is effective August 17, 2026 and replaces the incorrect 25% / 75% wording.
Key definitions use 12-calendar-month basis
Definitions for gross energy output, turbine tuning, and related terms now explicitly use a "12-calendar-month" basis; turbine tuning is limited to 30 hours per 12-calendar-month period. The corrected definitions are effective August 17, 2026.
CEMS missing-data estimation clarified
For units complying with the 12-calendar-month mass-based standard, emissions for hours with missing NOX CEMS data must be estimated using the average emissions rate of non-out-of-control hours within 10 percent of the hourly load value of the missing data during the 12-calendar-month period; if unavailable, use the maximum hourly rate. This correction is effective August 17, 2026.
Rule corrections are editorial and non-substantive
The EPA states these corrections are minor, noncontroversial, align the regulatory text with the preamble intent, and do not substantively change requirements or create new costs. The corrections are final and effective August 17, 2026.
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