Alabama Proposes Diesel Limits for Data Center
State regulators propose capping backup engines at Digi Power X's Columbiana campus, with public comments due within 15 days.
Updated on Nov. 2, 2026 in Data Centers
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The Alabama Department of Environmental Management proposed draft synthetic minor air permits on October 29, 2026, for Digi Power X's planned data center at 130 Industrial Parkway in Shelby County. The draft would limit each of 42 diesel engines to 90 hours of operation per rolling 12 months.
Why it matters
The permits set emissions limits for a large backup-power fleet at a data center, and the operating caps are a central part of how the state would keep the site below major-source thresholds. Residents and other interested parties can request a hearing or submit comments during the comment period.
The 42 engines range from 1,490 to 3,640 brake horsepower, and the draft allows diesel with a maximum sulfur content of 15 parts per million. ADEM's analysis projects 93.46 tons per year of nitrogen oxides and 36.91 tons of carbon monoxide, with no stack testing required.
The players
Alabama Department of Environmental Management (ADEM)
The state agency responsible for regulating air emissions in Alabama, which proposed the draft permits and will make the final permitting decision after public comment.
Digi Power X
The data center developer seeking the air permits for its Columbiana campus, which has also announced a 40 megawatt campus for Cerebras Systems under a $1.1 billion colocation agreement.
The details
Proviso 22 caps total operation at 90 hours per engine with no emergency carve-out, while Proviso 27 allows unlimited emergency use plus up to 100 hours a year for maintenance and readiness testing. Operators must log every run as emergency or non-emergency and report any overrun to ADEM within two working days.
Timeline
May 8, 2026: Digi Power X applied for the air permits.
August 13, 2026: Digi Power X filed a permit application addendum.
October 13, 2026: ADEM walked the greenfield site.
October 29, 2026: ADEM proposed the draft synthetic minor permits.
Comments and hearing requests are due within 15 days after publication.
Roadmap
The draft permits rely on the synthetic minor approach under the Clean Air Act, in which operating limits keep a facility under the 100-ton-per-year Title V threshold. The Columbiana proposal follows that pattern, using hour caps on 42 diesel backup engines to hold projected nitrogen oxides at 93.46 tons per year.
Residents near Columbiana and Shelby County can submit comments or request a hearing within 15 days of publication. The permit conditions determine how often the diesel backup engines can run and how emissions are reported to the state.
The takeaway
Permit terms that cap engine hours are a key lever in how large backup-power installations stay within state and federal emissions limits. Readers can watch how the final decision and any hearing shape the operating rules.
What happens next
ADEM's comment period runs 15 days after the October 29, 2026 publication, after which the agency will consider any hearing requests before deciding on the permits.
Further reading
Track the latest developments in Data Centers coverage across the state.
Source note: This article includes information reported by Environment+Energy Leader.
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