The Minnesota Pollution Control Agency (MPCA) recently introduced new requirements for the use of standardized emissions calculation spreadsheet forms in air permit applications. Beginning March 3, 2025 the use of the MPCA emission calculator forms was required for new individual State and Federal permits and amendments applications. The forms will be required for all new and unaffected permitted units included in new air applications. Facilities are encouraged to build extra time into their next permitting action to update historical calculations. This article summarizes the available spreadsheets for these new forms, applicability to the new forms, and additionally provides an overview of other existing emission calculations resources from the MPCA.
New Required Emissions Calculation Spreadsheet Forms for Permit Applications
The Emission Calculation Spreadsheets are provided in editable Excel format and are tailored to cover air emissions for specific facility types and operations, including:
Each calculator contains embedded guidance and regulatory references. A brief summary of applicable use cases as well as clarifications for non-applicable use cases of each form as specified by the MPCA within each spreadsheet’s “instructions” tab is shown in Table 1 below.
Table 1. Summary of Emission Calculation Spreadsheet Form Use Cases
| Form/Spreadsheet | Applicable Use Case | Non-applicable Use Cases |
| External Combustion | Bituminous and sub-bituminous coal, anthracite coal, fuel oil, natural gas, liquid petroleum gas, wood residue – AP-42 Sections 1.1 through 1.6 | Units with multiple fuels, lignite, bagasse (sugar mills), residential stoves/fireplaces, or waste oil combustion |
| Coating Air Emissions | Air atomization spray, airless spray, electrostatic/air atomization, electrostatic/airless, high volume low pressure, electrode deposition, powder, dip coating, roller coating, custom methods | Web or continuous coating methods |
| Internal Combustion Engines | Natural gas-fired reciprocating engines (2SLB, 4SLB, 4SRB) – AP-42 Section 3.2 Gasoline-fired engines up to 250 hp – AP-42 Section 3.3 Diesel-fired engines up to 600 hp – AP-42 Section 3.3 Dual-fuel engines using any of the above | Gasoline engines >250 hp Diesel engines >600 hp |
| Storage Piles Material Handling | Any outdoor storage piles with material handling operations (AP-42 Section 13.2.4) | – |
| Storage Piles Wind Erosion | Any outdoor storage piles with emissions generated from wind erosion (AP-42 Section 13.2.5) | – |
| Paved and Unpaved Roads | Any paved (AP-42 Section 13.2.1) or unpaved (AP-42 Section 13.2.2) roads | – |
| Grain Handling | Any grain handling operations including receiving, loadout, cleaning, drying, handling, and storage (AP-42 Section 9.9.1) | – |
| Landfills | Only calculates emissions from municipal solid waste landfills – calculate combustion of landfill gas (LFG) using the Engine or External Combustion Air Emissions Calculator | When landfill gas is shipped offsite (e.g., to RNG facility) |
| Woodworking | Any drilling, cutting, sanding, sawing, or other operations with wood or wood products (AP-42, Table 10.4.1) | – |
When to Use a Custom Spreadsheet
If your equipment or process is identified in the MPCA’s list of covered forms but the form does not accurately represent your operations or emission characteristics, you may use a custom emissions spreadsheet in place of the MPCA form. In this case:
- Continue preparing your emissions calculations using your own spreadsheet.
- Include a brief note in the permit application explaining why the MPCA form could not be used (e.g., process not represented, emission factor limitations, operational uniqueness).
- Ensure your custom spreadsheet still aligns with AP-42 methodologies or other MPCA-accepted emission factor sources and includes clear documentation.
The instructions tab of each MPCA form provides further guidance on what is and is not covered and clarity on exact methodologies used for calculations. Trinity recommends reviewing these definitions carefully when determining form applicability.
Small Business Air Emissions Calculators (Voluntary Use)
- In addition to the newly required emissions spreadsheet forms for air permit applications, the MPCA also offers a separate suite of air emissions calculators through the Small Business Environmental Assistance Program to help small businesses determine if they need an air permit and to track emissions as required by their current air permits. These Microsoft Excel-based tools are designed to help businesses:
- Determine whether they need an air permit
- Estimate potential and actual emissions for regulatory awareness
- Track emissions over time to maintain compliance
These calculators are not required for permitting but serve as a useful resource for facilities that do not currently hold permits or that need to maintain emissions records for internal or regulatory awareness.
Available calculators cover a wide range of common equipment and industrial processes, including:
- Abrasive blasting
- Aggregate processing
- Boilers and furnaces
- Coating and auto body facilities
- Engines (generators)
- Gasoline vapor recovery
- Grain elevators and feed mills
- Hot mix asphalt
- Storage tanks and vapor recovery
- Mechanical finishing
- Storage tanks
- Woodworking operations
Each calculator is linked through Small Business Environmental Assistance Program’s Air Emissions Calculators page and includes guidance on usage and recordkeeping.
Trinity is Available to Help
If you have questions about the new MPCA emissions calculation forms, Trinity can help clarify their applicability and use. If you’re planning a project that requires a new State or Federal air permit—or an amendment to an existing permit—we can assist with incorporating the updated calculation requirements into a complete air permit application. For more information on this topic, please contact Garrison Pierce or Trinity’s Minneapolis Office at 651.275.9900.
