EPA’s New Turbine Rules Provide Air Permitting Relief for Data Centers

On January 15, 2026, the EPA published New Source Performance Standards (NSPS) for stationary combustion and gas turbines. The EPA also provided permitting relief and the potential for permit exemption in the future. For combustion turbines, the rule categorizes sources based upon size, utilization rates, design efficiency, and fuel type and requires combustion controls for NOX with additional selective catalytic reduction for large combustion turbines with high utilization rates. Sulfur dioxide controls did not change.

In addition to these controls, the EPA, citing its June 2012 memorandum on Title V permit exemptions for combustion turbines, exempted from the Title V major source permitting program those combustion turbines that are not major sources or are located at major sources. This exemption would apply to small, medium, and large, low-use subcategories. Permitting these sources would now fall to the States’ non-major permitting programs. Moreover, to further streamline permits for these sources, the EPA has suggested that States use general permits or permits by rule.

The EPA also added a subcategory that covers small- and medium-sized combustion turbines that are used in “temporary” applications. Data center use of turbines in temporary applications has drawn criticism lately, leading to filing suit against a data center for operation of unpermitted emission units.

The temporary designation applies to combustion turbines up to 850 MMBtu/hour used for less than 24 months. A temporary turbine cannot be replaced with another temporary turbine to circumvent the permitting requirement.

Of interest to data centers using temporary turbines to provide power, the EPA indicated that it believes that combustion turbines are “a kind of internal combustion engine “ that could be regulated as nonroad engines (i.e., mobile sources) under Title II of the Act. However, the current definition of “nonroad engine” does not include combustion turbines. The effect of this change is to exempt such turbines from the new source review permitting requirements of the Act because it will no longer be considered part of the stationary source.

In the final rule, the EPA includes a conditional exclusion for temporary turbines. The exclusion removes combustion turbines from the definition of “stationary combustion turbines” if the turbine meets the definition of nonroad engine and is certified to meet emission standards adopted under Title II of the Act. According to the EPA, this exclusion will become effective if the EPA adopts nonroad emission standards and certification requirements for portable combustion turbines. At that time, the manufacturer of combustion turbines will be subject to the Title II requirements for mobile sources, including obtaining certificates of conformity.

The EPA recognized that its approach requires further consideration before any rulemaking is initiated. However, it did not give any indication of when it may propose non-road engine emission standards and certification requirements under Title II.

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