Minnesota’s data center market is expanding rapidly as demand for AI infrastructure, cloud computing, and digital storage continues to grow. While these facilities are not typically large emitters during normal operations, the presence of emergency backup generators makes air permitting a critical consideration. As more data centers enter the pipeline, understanding the Minnesota Pollution Control Agency’s (MPCA) permitting approach is essential. With state regulators placing increased attention on emissions from these generators, particularly as large campuses are planned and constructed, now is the time to understand your air permitting obligations and ensure your facility-wide emissions are properly evaluated.
Why are Air Permits Required for Data Centers
The primary driver for air permitting data centers is the fleet of emergency backup generators, typically powered by diesel engines. Although these generators operate infrequently, their cumulative Potential to Emit (PTE) can exceed federal and state thresholds thus triggering air permitting requirements.
Under Minnesota Rules Chapter 7007, any facility with a PTE above the thresholds listed in Minn. R. 7007.0200 and Minn. R. 7007.0250 must obtain an air emission permit. These thresholds include:
- 100 tons per year (tpy) of any regulated pollutant (CO, NOX)
- 100,000 tpy of CO2e
- 0.5 tpy of lead
- 50 tpy of SO2
- 25 tpy of PM-10
- 100 tpy of VOCs
- 10 tpy for any single hazardous air pollutant (HAP)
- 25 tpy for combined HAPs
Even though emergency generators are exempt from certain federal standards when used only in emergency situations, these units still count toward the facility’s PTE in Minnesota. Testing and maintenance hours must also be included in emission calculations, which can add up quickly when facilities have dozens of units.
What is PTE and Why is it Important?
PTE refers to the maximum quantity of air pollutants a facility could emit if its equipment ran at full capacity without restrictions. For data centers, this is generally calculated based on the generator nameplate rating, emissions factors, and hours of operations. Even when emission controls are in place, or when equipment only operates occasionally, PTE calculations must reflect the full potential output unless enforceable limits are in place (e.g. maximum hours of operation in a year, restricting usage of fuel). The facility-wide PTE determines which type of air permit, if any, is required. As part of permitting, MPCA may also require air dispersion modeling. A further breakdown on permit applicability can be found on the MPCA’s Air Permit Types website. Data center projects that do not proactively evaluate their facility-wide PTE risk delays in permitting process or noncompliance.
Other Considerations
While air permitting is a primary environmental focus for data centers, several other factors may impact project planning and regulatory timelines:
- Noise and Vibration: Backup generators and rooftop equipment can generate significant noise during operation. Noise assessments and mitigation may be required to comply with local ordinances or avoid disruption to nearby communities
- Utilities: Data centers place high demand on electric, water, and sewer infrastructure. Utility expansion may trigger additional permitting or coordination with local providers and municipalities.
- Endangered Species: Construction activities could affect sensitive habitats. Site-specific reviews may be necessary to determine whether threatened or endangered species are present and to identify avoidance or mitigation measures.
- Stormwater Management: Construction will typically require erosion control measures and a stormwater permit. Early planning for site grading, runoff control, and sediment containment is essential.
If you have any questions regarding permitting a data center in Minnesota, please contact Trinity’s Minneapolis Office.
