Amazon and Duke Energy are installing 649 diesel generators to back a hyperscale datacenter in North Carolina under two separate air permits — a combined emissions profile of nearly 250 tons per year of nitrogen oxides, carbon monoxide and volatile organic compounds that, environmental advocates allege, was structured precisely to avoid a federal "major" source review under the Clean Air Act.

The North Carolina project, filed with state regulators, also includes about 98 tons per year of particulate matter and 6.4 tons per year of hazardous air pollutants, including benzene and formaldehyde, from Amazon's portion of the generators, according to permit documents reviewed by The Guardian.

The tactic is not isolated. Environmental advocates say big tech developers are increasingly dividing emissions sources into multiple "minor" permits that individually fall below federal thresholds, avoiding the stricter oversight, public scrutiny, pre-construction monitoring and potential pollution control requirements — such as scrubbers — that come with a major source designation. Minor permits are also typically approved much faster.

Datacenters with on-site generation can be significant sources of nitrogen oxide, ozone, heavy metals, particulate matter and greenhouse gases.

The New Mexico case

The clearest documented example is Project Jupiter in New Mexico, developed by Austin-based BorderPlex. The developer proposed two natural gas "microgrids" on either side of the facility and submitted two minor permit applications to state regulators. The combined project would have released enough pollution to trigger a major review.

The federal limit for a minor permit for hazardous air pollution is 25 tons per year. Each microgrid was proposed to emit between 20.2 and 24.2 tons — meaning together they could have released as much as 44 tons of hazardous air pollutants annually.

The plan was "nothing short of preposterous," attorneys with the New Mexico Environmental Law Center wrote in March comments submitted to state regulators, noting it would have effectively allowed one natural gas power plant to operate on two minor permits. The firm represents community members who would be affected by the project's pollution.

Attorney Maslyn Locke wrote in regulatory documents that the "audacious attempt to arbitrarily distinguish two halves of the same source is insulting to both [regulators] and community members, as it is so clearly an attempt to avoid air pollution control requirements."

BorderPlex withdrew the application in April amid fierce community pushback. The New Mexico Environment Department also opposed the proposal, a spokesperson said — though Locke noted there was no public evidence of regulatory opposition until now. New plans for the datacenter remain held up before the state supreme court over procedural problems, according to Locke.

Maryland and the broader pattern

In Frederick, Maryland, four datacenters — including one operated by Amazon — hold separate minor permits but operate on a single campus under a master developer, according to Maryland Department of the Environment regulatory documents. In other instances, developers have staggered minor permit requests over months in configurations that cumulatively emit as much as a major source, advocates say.

Michael Koerber, retired deputy director of the EPA's Office of Air Quality Planning and Standards, calls the practice "lego permitting."

"They want to fly under the radar," said Koerber, who now volunteers with the Environmental Protection Network. "The more attention they have, the more difficult it gets to get the permit. They have consultants who are very good and know where the shortcuts are."

Koerber noted the practice is not unique to datacenters. Cheryl Vetter, a former EPA colleague who left the agency last year, said the tactic was not common among datacenter developers until recently.

Vetter explained that divided permits are lawful in some circumstances: two separate companies may polluting at the same location can hold separate permits, but not where all polluting activities sit under common control. Sources must also be adjacent, though "adjacent" can extend to facilities that do not share a border but operate as part of the same operation.

The North Carolina dispute

The Amazon–Duke project sits in a low-income region already burdened by emissions from a Duke power plant and a plastic pellet factory, the Southern Environmental Law Center (SELC) wrote in comments to North Carolina regulators. Heart disease, cancer and respiratory disease are among the leading causes of death in the region.

North Carolina regulators wrote that Duke's generators will provide temporary power for about a year and that Duke operates them separately from Amazon's units. But SELC attorney Kathleen Sullivan alleged the companies did not provide lease agreements or contracts to regulators, and some documents suggest Amazon controls all the generators.

State regulators are "simply trusting two extremely wealthy and politically powerful companies without any verification," Sullivan said. "North Carolina regulators failed to protect people's health and the air we all breathe by blindly accepting the companies' self-interested statements instead of doing their job to investigate the key facts."

She added that even temporary operation warrants scrutiny, because an hour of exposure to dangerous pollutants can cause health problems.

An Amazon spokesperson said in a statement that the company "appropriately applied for and obtained an air permit for our datacenter project" and that "the separate permitting of Amazon's and Duke's respective projects reflects the actual ownership and operational structure."

"They should be – and are – permitted under separate air permits," the spokesperson said.

The immediate milestones to watch are procedural. New Mexico's supreme court must resolve the procedural challenges holding up Project Jupiter's revised plans, and North Carolina regulators must decide whether to demand the ownership and lease documentation that SELC says would establish common control over the 649 generators — the factual question that determines whether the installation constitutes a major source under the Clean Air Act.