Coming Soon: A Trump EPA proposal to weaken pollution limits for the turbines that power data centers

The Trump EPA is soon expected to take another step to weaken protections against dangerous air pollution – this time to benefit certain combustion turbines used to power data centers. 

The agency just sent a proposal, Nonroad Combustion Turbines Rule, to the White House for final review. It’s expected to exempt these combustion turbines from Clean Air Act standards that apply to industrial sources – and instead regulate them as “mobile” sources akin to vehicles or offroad equipment. That would allow their health-harming pollution to affect nearby communities with no public notice, no public engagement, no review of local air quality impacts, no assessment of cleaner alternatives, and insufficient oversight to ensure these combustion turbines comply with the minimal health protections that would apply. 

Here are some things you should know: 

Right now, gas-powered turbines that provide power for data centers must obtain permits to ensure they limit pollution

Data centers are increasingly relying on clusters of smaller, trailer-mounted, gas-powered combustion turbines for power (litigation over the xAI plant in South Memphis has highlighted that). These turbines emit dangerous pollution including smog-forming nitrogen oxides (NOx), carbon monoxide, particulate matter and toxic formaldehyde.  

For decades, EPA has required such turbines to obtain Clean Air Act permits, which provide enforceable limits on harmful pollution, and to comply with the Clean Air Act protections that apply to other power plants, industrial facilities and similar stationary sources of emissions. Specifically, they generally must procure Title V operating permits and New Source Review pre-construction permits and must comply with pollution limits including the Clean Air Act Section 111 New Source Performance Standards for NOx that EPA revised in January. (In that January action, EPA did exempt certain smaller combustion turbines from having to obtain Title V permits.)  

New Source Review and Title V permits provide protections like: 

• Requirements for the use of modern pollution control technology to protect local air quality. 
• Assurance that new pollution from a source will not interfere with a community’s attainment of health-based National Ambient Air Quality Standards. 
• Notice to the public about the facility, its pollution, and local air quality impacts, and an opportunity for the public to provide comments on draft permits. 
• Enforcement and compliance mechanisms, like making sure regulators receive emissions monitoring data to assess ongoing compliance with pollution standards. 

Industry interests have asked EPA to exempt portable combustion turbines used in data center applications from health protections 

Last year, the Coalition of Mobile Electric Turbine Users (COMET), a group of manufacturers and users of combustion turbines, petitioned EPA to exempt trailer-mounted combustion turbines that use methane gas and distillate fuels from these requirements.  

The petition asks EPA to regulate these combustion turbines as “nonroad engines” under Title II of the Clean Air Act, which generally pertains to mobile sources like cars and trucks. If deemed “nonroad engines,” these combustion turbines would not need to comply with Title V or New Source Review protections and would be exempt from the public notice, pollution control, and compliance assurance requirements that these programs provide.   

In January’s revisions of the NOx standards, EPA signaled openness to creating exactly the exemptions that COMET requested. EPA also finalized regulatory language that would make such exemptions effective as soon as the agency finalizes the change to mobile source standards for these turbines. 

Exemptions would undermine health protections and keep people in the dark about large sources of pollution  

Data centers are using dozens of portable combustion turbines clustered together as de facto large gas power plants. Together these clusters emit as much pollution as single large power plants.  

For example, the 27 gas turbines at xAI’s Mississippi location have the potential to release 1,700 tons of smog-forming NOx, 180 tons of particulate matter, 500 tons of carbon monoxide, and 19 tons of formaldehyde each year. This pollution is tied to cancer, heart and lung diseases, asthma attacks and other serious health problems.   

If EPA grants these portable plants exemptions, it will create loopholes for new large, polluting power plants to be built without required Clean Air Act protections.  

Also, under EPA regulations, “nonroad engines” must not remain at the same location for more than one year. But because no permit is required, EPA and local regulators often have no way to enforce this requirement. And even if the units are “temporary,” a loophole would allow substantial pollution into communities for a whole year without critical health protections that would otherwise apply. 

Although data centers are among the industry sectors most engaged in deploying these portable combustion turbines, EPA’s proposal is not expected to be limited to the turbines used at data centers. The proposal is likely to fast-track many other applications, including facilities in the oil and gas sector, as well.