Air Enforcement: Mississippi Commission of Environmental Quality and Southaven Gas-Fired Combustion Turbines Operator Enter Into Agreed Order

The Mississippi Commission of Environmental Quality (“MCEQ”) and MZX Tech LLC (“MZX”) entered into a July 30th Agreed Order (“AO”) addressing the operation of what is described as:

… sixty-nine (69) portable, temporary simple cycle natural gas-fired combustion turbines…

The AO provides that MZX operates the 69 turbines on its property located in Southaven, Mississippi (“Stanton Road Facility”).

The National Association for the Advancement of Colored People (“NAACP”) had filed a May 6th Motion for Preliminary Injunction in the United States District Court for the Northern District of Mississippi against X.AI Corp. and MZX requesting an injunction arguing the operations violate the Clean Air Act. Further, the United States Department of Justice subsequently filed an action to intervene and to dismiss the NAACP’s action.

The Mississippi Department of Environmental Quality (“MDEQ”) are stated to have acknowledged on July 29, 2025, that the turbines remaining affixed to a portable unit and remaining on site for twelve months or less constituted “mobile sources” that are not subject to stationary source air permitting requirements under the relevant section of the Mississippi Administrative Code. The AO indicates that MDEQ’s letter requested that MZX operate the mobile turbines in a manner that minimizes the emission of nitrogen oxides (NOX) and particulate matter less than 2.5 microns in diameter (“PM2.5”) through the implementation of additional emission control technology available and applicable to portable combustion turbines.

MZX is stated to have implemented such controls.

The AO also describes:

• MZX’s representation that the use of each mobile turbine would be temporary.
• MDEQ exercised its discretion to allow the operation of the turbines as “mobile sources” under the state’s EPA-approved State Implementation Plan.
• MZX was requested to use each mobile turbine for no more than one year and ensure each mobile turbine would remain portable at all times.

MZX is stated to have provided the following:

• Unit number.
• Unit type.
• Emission control.
• Total power output.
• Date added for each mobile turbine on site at the Stanton Road Facility.

Control technology for 14 turbines is described and it is asserted that they are capable of meeting or exceeding the emission limitations required by the Clean Air Act’s Best Available Control Technology standards.  

The AO also states:

• Mississippi Environmental Quality Permit Board issued a Prevention of Significant Deterioration (“PSD”) Permit to Construct Air Emissions Equipment at the Stanton Road Facility.
• The PSD permit imposes the most stringent emission limitations applicable to stationary combustion turbines located at a major stationary source.
• Due to supply chain challenges, the construction schedule for some of the 41 stationary combustion turbines covered by the PSD permit has been delayed, requiring the need to operate the 13 of the 14 SMT-130 mobile turbines beyond the original twelve-month period.
• MZX has proposed a retirement schedule for the use of mobile turbines as outlined in Appendix A of the AO.

MDEQ and MZX agree to certain operational limitations, reporting obligations, testing requirements, and schedules for operations in paragraphs A – G of the AO. Failure to adhere to any of the Conditions B – F for a particular mobile turbine means it will immediately cease to qualify as a mobile source as described in the relevant provision of the Mississippi Administrative Code.

A copy of the AO can be found here.