xAI's 35 turbines against a permit for 15: the Memphis record

What was built

xAI converted a former appliance factory in South Memphis into Colossus in 2024 at a speed the local grid could not match, so the site drew its primary power from methane gas turbines trucked in and connected on site. SemiAnalysis estimates the cluster at around 200,000 H100 and H200 GPUs plus 30,000 GB200s, drawing about 300 MW.

What was permitted

In July 2025 the Shelby County Health Department issued a permit covering 15 turbines, which xAI described as backup, with emissions controls, capable of up to 247 MW. Campaigners said xAI had operated as many as 35 turbines without permits before that, with a combined capacity of about 421 MW. The Southern Environmental Law Center's aerial and satellite imagery showed 35 units on site at one point and 24 operating in July, and its modelling put the fleet's nitrogen-oxide output above 2,000 tons a year.

The response

SELC, Earthjustice and the NAACP sent xAI a notice of intent to sue under the Clean Air Act. The NAACP and Young, Gifted and Green appealed the 15-turbine permit to the Memphis and Shelby County Air Pollution Control Board, contesting the health department's determination that temporary gas turbines are "nonroad engines" exempt from permitting. xAI called the allegations "baseless and politically driven" and said that once a new 150 MW substation came online it would use gas for backup only.

Why it matters for the index

Two pillars. Carbon: on-site fossil generation for primary power is the bottom band of the rubric, and Colossus is its defining case. Conduct: operating beyond a permit, with pending Clean Air Act litigation, is the bottom band of that rubric too. xAI's conduct score is 8 and its carbon score 12, the lowest on the site. The incident is one of three on the profile; Colossus 2 in Southaven repeated the pattern a year later.

The community

The turbines sit in a part of South Memphis already carrying a steel mill, a gas plant and an oil refinery, where residents had asked for years for relief from industrial air pollution. The permit fight is about turbines; the grievance it sits inside is older than xAI.