Permit applications must include detailed emissions calculations on form GI-07 (Facility Emissions Summary) or CAP-GI-07. The calculations help determine which permit type or permit amendment is needed. The information must be provided in the permit application, and in an editable spreadsheet that includes all formulas/equations in the calculated cells.

Calculating potential emissions

Methods for calculating a facility's potential to emit include:

  • Using emission factors – emission data from the U.S. EPA's Compilation of Air Emission Factors or its Factor Information Retrieval (FIRE) Data System. Applicants must use whichever is most representative and accurate.
  • Material balance methods
  • Direct measurement of emissions

Describe any bottlenecks or physical limitations in your process(es) that restrict your potential-to-emit. Describe any permit limits you will propose (fuel type or usage, hours of operation, bottlenecks, etc.) that would restrict your potential to emit:

Calculating actual emissions

Minnesota rules specify the preferred methods for calculating a facility’s actual emissions:

  1. Continuous emission monitor data
  2. Performance test data
  3. Volatile organic compounds material balance, sulfur dioxide material balance, emission factor, or enforceable limits
  4. Facility proposal

Emissions spreadsheet requirements

Create an editable spreadsheet with the applicable information indicated below and on the pages at left. Each step in your calculations needs to be clear and easy to follow.

Facility information

  • Air quality facility ID number, the first eight digits of the permit number for operating permits
  • Air quality file number if you know it. It's included in the "cc" section of correspondence from the MPCA.
  • Facility name
  • Emissions units, including fugitive sources, storage tanks, etc. Include the ID number for each unit and a description of the unit.
  • Stack/vent designation numbers, in Form GI-04 or similar form, except when applying for registration permit Option D
  • Pollution control equipment, including each unit's identification or designation number and a description of the equipment. If none, indicate no control equipment. If you are applying for a registration permit Option D, just provide a description of the control equipment.
  • Ovens used to dry or cure coating or printing, if applicable. Not applicable for electric heat or UV-curing ovens. Indicate the number of ovens, the fuels that can be used, and the total rated heat inputs. Include any information required for external combustion units.
  • Batch or continuous process type, if applicable
  • Maximum capacity, or the maximum number of units that can be processed per hour and the units used. If needed, attach additional sheets to describe the process and any rate limiting steps.
    • For grain elevators and feed mills: Calculate maximum capacity by multiplying the highest grain throughput of the previous five operating years by 1.2. For terminal grain elevators or feed mills, indicate the capacity of each emission unit.
  • Source of emission factors, U.S. EPA's Compilation of Air Pollutant Emission Factors (AP-42) or its WebFIRE database. Not applicable to plating processes.
  • Operating limitations, or the permit limits you propose to restrict your potential-to-emit – see Synthetic minor permit limits. Attach additional spreadsheets or other information, if needed. Cite any rules that apply.
  • Additional emissions calculations on a separate worksheet. This is for emissions units described by the calculations that include other types of emissions. For example, an emissions process or unit that also burns fuel, uses solvents, or emits greenhouse gases will need a separate worksheet for those secondary emissions.
  • For internal combustion engines and external combustion units: Provide fuel parameters for each type of fuel used – fuel type, sulfur content and ash content in weight percent, heating value (i.e., BTU/ton, BTU/cf, etc.), and manufacturer's fuel consumption rate (or calculate by multiplying maximum rated capacity by heating value)

Internal combustion engines

In addition to the item above, provide:

  • Engine type – Reciprocating, turbine, or other (provide description)
  • Engine purpose, routine operation or emergency use. Complete a screen model for ambient air impacts, unless it's a generator used only for emergencies.
    • EC-03: IC Engine Screen Modeling (aq-f1-ec03)
  • Rated heat input, in units of million British thermal units per hour (MMBTU/hr).
  • Rated mechanical output, in horsepower at a specified rpm.

Plating processes

In addition to the item above, provide:

  • Describe the type of plating, such decorative chrome, hard chrome, chromic acid, or other.
  • Operating parameters: Note the capacity in total amps for an electroplating operation, or the capacity in total square foot per hour capacity for an anodizing operation.
  • List the pollution-emitting solutions or chemicals used in the plating process.

Woodworking processes

Provide the facility ID, file number, name, emissions units, stack/vent designation numbers, pollution control equipment, and source of emission factor information as indicated above. In addition, include:

  • Maximum throughput of air in cubic feet per minute (cfm) for each emission unit

Emission calculations

Generally, you will list the pollutants your facility emits in the left column, and each calculation will be another column in your spreadsheet. Provide the formula or equation for each calculation. Add columns for additional calculations or to provide information specific to your operation. See the Greenhouse gas emissions calculations page for calculation instructions for GHG-emitting units.

  • List the pollutants that the process or unit emits:
    • Particulate matter (PM)
    • PM smaller than 10 microns (PM10)
    • PM smaller than 2.5 microns (PM2.5)
    • Sulfur dioxide
    • Nitrogen oxides
    • Volatile organic compounds
    • Carbon monoxide
    • Hazardous air pollutants (HAPs), listed individually
    • Total emissions from HAPs
    • Greenhouse gases, listed individually. Provide the carbon dioxide equivalent amount.
    • Fluorides
    • Sulfuric acid mist
    • Hydrogen sulfide
    • Total reduced sulfur (includes hydrogen sulfide)
    • Reduced sulfur compounds (includes hydrogen sulfide)
    • Municipal waste combustor (MWC) organics
    • MWC metals
    • MWC acid gases
    • Municipal solid waste landfill gases
  • For each pollutant, provide the emission factor in pounds per unit of production, or per unit of material usage from either the U.S. EPA's Compilation of Air Pollutant Emission Factors (AP-42) or its WebFIRE database. Show any calculations used to determine maximum continuous rates. Attach a separate sheet, if necessary.
    • For woodworking operations: Use the AP-42 emission factors for particulates (1.57E-05 lb/scf for sanding and 8.57E-06 lb/scf for sawing, drilling, and other woodworking) unless you provide documentation supporting other emission factors.
  • Calculate the emission rate by multiplying the emission factor by the maximum capacity of the operation (in units of production per hour, material usage per hour, or the units the emission factor is in).
    • For external combustion units: Emission rate (lb/hour) = Emission factor (lb/unit) x Fuel consumption rate (unit/hr).
    • For internal combustion engines: Multiply the emission factor by either the fuel consumption rate (lb/unit), the rated mechanical output (horsepower), or the rated heat input.
    • For plating processes using emissions factors in pounds per amp-hour: Emission rate (lb/hr) = Emission factor (lb/amp-hr) x Electroplating capacity (amps). For plating processes using emissions factors in pounds per square foot-hour: Emission rate (lb/hr) = Emission factor (lb/hr-ft2) x Anodizing capacity (ft2)
    • For woodworking processes: Emission rate (lb/hr) = Emission factor (lb/scf) x Air throughput rate (scf/min) x 60
  • Calculate the maximum uncontrolled emissions. Skip this step if you are applying for a registration Option D permit.
    • Max. uncontrolled emissions (tons/year) = Emission rate (lb/hr) x 8760 (hr/yr) x [1 ton ÷ 2000 lb]
    • For internal combustion engine (emergency generator): Max. uncontrolled emissions (tons/year) = Emission rate (lb/hr) x 0.25 {8760 (hours/year) x [1 ton ÷ 2000 lb]}
    • For internal combustion engine (not emergency generator): Max. uncontrolled emissions (tons/year) = Emission rate (lb/hr) x 4.38 [(hours/year) x (tons/lb)]
    • For plating processes: Maximum uncontrolled emissions (tons/yr) = Emission rate (lb/hr) x 8760 (hrs/yr) x 0.0005 (tons/lb)
  • Include the pollution control efficiency percentage, which is the capture efficiency percentage multiplied by the destruction/collection efficiency percentage (shown on Form GI-05A or similar), for each pollutant. Form CD-05 also requires a plan to demonstrate and maintain the destruction/collection efficiency. If there is no control for a particular pollutant, indicate “zero” as the control efficiency.
  • Find the maximum controlled emissions rate:
    • Maximum controlled emissions rate (lb/hr) = Emission rate (lb/hr) x {[100 - Pollution control efficiency] ÷100}
  • Calculate the maximum controlled emissions:
    • Max. controlled emissions (tons/year) = Max. uncontrolled emissions [tons/year] x {[100 - Pollution control efficiency] ÷100}
  • Include the maximum hourly emission rate allowed under 40 CFR pt. 60, 40 CFR pt. 61, 40 CFR pt. 63, or Minn. R. ch. 7011. See form GI-09 for applicable regulations.
  • Find the limited controlled emissions (tons/year) by repeating the emission rate calculation (multiplying the emission factor by the maximum capacity of the operation) but take into account all your facility's operation limits, such as hours of operation, amount of material handled, etc. If an emission unit is subject to an emission limitation specified in 40 CFR pt. 60, 40 CFR pt. 61, 40 CFR pt. 63, or Minn. R. ch. 7011 or you are proposing a more stringent limit, you must indicate this and include those factors in the calculation. Skip this step is you are seeking a registration Option D permit.
  • For external combustion units and internal combustion engines: Indicate actual annual fuel use with the unit's average fuel use per year for the past two years. For registration permit Option D applicants, report fuel used in the most recent 12 months, (i.e. if calculating in July, use July 1 of last year through June 30 of this year).
  • Calculate actual uncontrolled emissions:
    • Actual uncontrolled emissions (tons/year) = Emission factor (lb/unit) x [1 ton/2000 lb]
    • Does not apply to external combustion or woodworking units
  • Calculate actual controlled emissions:
    • Act. controlled emissions (tons/year) = Act. uncontrolled emissions [ton/year] x [100 - Pollution control efficiency]
    • For external combustion units, internal combustion engines, and woodworking units: For existing units, take an average of the usage data from the previous two calendar years, or average the previous two emission inventory reports. For registration permit Option D applicants, use the previous 12 months of operation. For new units, or where records don't exist, estimate the hours of unit operation and fuel use.
      • Actual uncontrolled emissions (tons/year) = Emission factor [lb/unit] x Actual annual fuel use (units) x {[100 - Pollution control efficiency] ÷100}.
      • If the emission factor is in pounds per hp-hr power output or pounds per MMBtu heat input: Actual uncontrolled emissions (tons/year) = Emission rate [lb/hour] x Actual operating hours (hours) 0.005 (ton/lb) x {[100 - Pollution control efficiency] ÷100}.
      • For woodworking units: Actual controlled emissions (ton/yr) = Emission factor (lb/acf) x Actual annual air throughput (units) x {[100 - Pollution control efficiency] ÷ 100}
  • For external combustion units: If the unit can combust any other fuels, provide all the applicable emission calculations above for each fuel type.
  • For external combustion units: Find the PTE before operating limits and the PTE after operating limits for the unit. Compare the maximum uncontrolled emissions columns for all fuel types used and indicating the highest PTE before limits. Compare the limited controlled emissions columns for all fuel types and indication highest PTE after limits.