Dozens of temporary gas turbines in Mississippi powering a huge SpaceXAI data centre in neighbouring Tennessee have caused a major spike in nitrogen oxide air pollution, satellite data suggests. SpaceXAI and local authorities dispute the claim. SpaceXAI’s Colossus 2 data centre in Tennessee came online in 2025 and is now the largest operational data centre in the US, servicing the firm’s rapidly growing artificial intelligence technology.
However, the site has been embroiled in controversy over its use of temporary gas turbines. Campaigners say these turbines are contributing to hazardous levels of air pollution in the surrounding area, and there are ongoing legal cases over their use, pursued by campaigners and local residents against SpaceXAI and its subsidiary MZX Tech. AI data centres can warm surrounding areas by up to 9.1°C Normally, emissions of NOx and other air pollutants from gas power plants are controlled using catalytic converters, but most of the temporary turbines powering the Colossus 2 plant don’t have them fitted.
NOx gases can inflame the airways and exacerbate the symptoms of people already suffering from lung or heart conditions. They also react with other air pollutants to form ozone and particulate matter, both key components of urban smog. Kevin Gauld at the Massachusetts Institute of Technology and his colleagues used observations from NASA’s TEMPO satellite – launched in 2023 to monitor air pollution over North America – to assess the impact of the Colossus 2 plant on local air quality.
The satellite observations show a “strong increase” in local NOx concentrations from late 2025 onwards, according to the study by Gauld’s team, which is when SpaceXAI began deploying the temporary turbines to Colossus 2. The researchers then used the TEMPO satellite to calculate two-week-average NOx source rates from August 2025 to mid-August 2026. They first detected NOx emissions in December 2025, and emissions increased throughout the study period.
The number of turbines on the site rose during the study period, from 27 in December 2025 to 69 by August 2026. The satellite analysis suggests that emissions averaged about 730 kilograms per hour between February and August 2026, peaking at 1180 kg per hour in August 2026. By comparison, the monthly emissions from a nearby gas power plant in Mississippi averaged just 21 kilograms per hour of NOx emissions, the paper reports.
Martyn Chipperfield at the University of Leeds in the UK, who wasn’t involved in the study, says the pollution levels observed by the satellite are significant. Can floating data centres meet AI’s huge energy demand? Ronald Cohen at the University of California, Berkeley, says the paper is “solid” science.
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