General processes or units emission calculations

This method may be used to develop an editable spreadsheet containing detailed emissions calculations for processes or units that cannot be accounted for in other process/unit specific emissions calculations instructions. Each step in your calculation(s) needs to be clear and easy to follow.

Include the following information with your calculations:

  • AQ Facility ID No. — Include your Air Quality (AQ) Facility identification (ID) Number (No.). This is the first eight digits of the permit number for all permits issued under the operating permit program. If your facility has never been issued a permit under this program, do not include it at this time.
  • AQ File No. — Include your AQ File Number, if known. This number can be found in the “cc” section of correspondence from the Minnesota Pollution Control Agency (MPCA). If you don't know or can't find this number, do not include it at this time.
  • Facility name — Include your facility name.
  • Emission unit or other identification number(s) — Include the identification number of the emission unit (EU), fugitive source (FS), tanks, etc. Obtain this number from Form GI-05B or the appropriate form related to the permit you are applying for, or your existing permit.
  • Stack/Vent designation number(s) — Fill in the designation number of the stack(s) or vent(s) through which the unit will exhaust into the atmosphere. Obtain these numbers from form GI-04 or the appropriate form related to the permit you are applying for, or your existing permit.
  • Pollution control equipment identification number(s) — Include the designation number of the control equipment (CE) through which the equipment will exhaust. Obtain this number from Form GI-05A or the appropriate form related to the permit you are applying for, or your existing permit.
  • Process type – Determine if your process is batch or continuous and indicate that clearly in the spreadsheet.
  • Maximum capacity – Indicate the maximum number of units that can be processed on an hourly basis and clearly state the units used. Additional calculation sheets may be attached to further describe the process and any rate limiting steps.
  • Source of emission factors – Indicate the source of your emission factors. Possible sources include those listed on the Emissions Calculations page, and described in Minn. R. 7005.0100, subp. 10.
  • Formula/Equation – The formula and/or equation needs to be available in the cell for each calculation step (for example, steps 3, 4, 6, 7, 9, 10 and 11 below.
  • Operating limitations – Describe in detail any permit limits you plan to take to restrict your potential-to-emit (fuel type and/or usage, hours of operation, bottlenecks, etc. - see Proposing Synthetic Minor Permit Limits). Attach additional spreadsheets or other information, if needed. Describe the limiting factors, cite any rules that apply (e.g., Standards of Performance for Stationary Sources (NSPS, 40 CFR part pt. 60), Best Available Control Technology [BACT]). The associated limit must be used to calculate your potential-to-emit after permit limits in Step 9. If you used vendor certification or stack test data to limit your potential-to-emit, the factor you used will become your permit limit. Include all proposed limits on Form CD-01, and anywhere else as instructed in the application forms.
  • Additional Emissions Calculations for this unit(s) – If the emissions units described by these calculations include other types of emissions, include calculations for those emissions on a separate worksheet. For example:
    • If this process/unit combusts fuel, include fuel combustion emissions.
    • If this process/unit uses clean-up solvents in addition to the process described by these emissions calculations, include emissions calculations.
    • If this process/unit emits greenhouse gases, include greenhouse gas emissions as described in Greenhouse Gas Emissions: Instructions for Emission Calculations Spreadsheets.

Emissions calculations

Follow these steps for calculating your emissions for each emissions unit or group, including fugitive sources and tanks. Additional columns can and should be included in the spreadsheet to indicate additional steps or information specific to your process.

Step 1. Pollutant

Include each of the following pollutants that your process emits.

  • PM = particulate matter
  • PM10 = particulate matter smaller than 10 microns in aerodynamic diameter
  • PM2.5 = particulate matter smaller than 2.5 microns in aerodynamic diameter
  • SO2 = sulfur dioxide
  • NOX = nitrogen oxides
  • VOC = volatile organic compounds
  • CO = carbon monoxide
  • HAPs = hazardous air pollutants – each individual hazardous air pollutant. See EPA's Web site for more information.
  • Total HAPs = All HAPs added together
  • Greenhouse Gas (individual greenhouse gases, and as CO2e)
  • Fluorides
  • H2SO4 = Sulfuric acid mist
  • H2S = Hydrogen sulfide
  • Total reduced sulfur (includes H2S)
  • Reduced sulfur compounds (includes H2S)
  • Municipal waste combustor (MWC) organics
  • MWC metals
  • MWC acid gases
  • Municipal solid waste landfill gases

Step 2. Emission Factor

For each pollutant, include the emission factor in pounds per unit of production or per unit of material usage obtained from the source(s) indicated above.

Step 3. Emission Rate [lb/hour]

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 whatever units the emission factor is in).

  • Emission rate [lb/hr] = Emission factor [lb/unit] x Maximum capacity [units/hour]

Step 4. Maximum uncontrolled emissions

Calculate the maximum uncontrolled emissions by multiplying the hourly emission rate by 8760 hours per year, and dividing by 2000 pounds per ton. This is the ‘maximum unrestricted emissions’ in tons per year to be included in the middle column of item 3e on Form GI-07.

  • Maximum uncontrolled emissions [tons/year] = Emission rate [lb/hour] x 8760 [hour/year] x [1 ton/2000 lb]

Step 5. Pollution control efficiency

Include the pollution control efficiency. The pollution control efficiency is the product of the capture efficiency and the destruction/collection efficiency indicated on Form GI-05A (or other similar form, depending on the type of permit you are applying for), or in your permit. Enter this number here and remember to include on Form CD-05 a plan to demonstrate and maintain the destruction/collection efficiency. The efficiency should be expressed for each pollutant. If there is no control for a particular pollutant, indicate “zero” as the control efficiency.

  • Pollution Control Efficiency [%] = capture efficiency [%] x destruction (or collection) efficiency [%]

Step 6. Maximum controlled emissions rate [lb/hr]

This is the maximum controlled lb/hr required in the first column of item 3e on form GI-07.

  • Maximum controlled emissions rate [lb/hr] = Emission rate [lb/hr] x {[100 - Pollution control efficiency] ÷100}

Step 7. Maximum controlled emissions [tons/year]

Calculate the maximum controlled emissions using the following formula:

  • Max. controlled emissions [tons/year] = Max. uncontrolled emissions [ton/year] x {[100 - Pollution control efficiency] ÷100}

Step 8. Hourly Emission Rate Allowed by State Rule or Federal Regulation

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 information on applicability of the various regulations.)

Step 9. Limited controlled emissions [tons/year]

Limited controlled emissions are calculated by taking into account all limitations on operation of the source you are proposing to comply with in this application. These limitations include limits on hours of operation, on the amount of material mined, handled, crushed, screened, etc. You start the calculation of limited controlled emissions by repeating the calculation of emission rate [step 3] but taking into account the limits you propose. This is the limited controlled emissions in tons per year in the right column of item 3e on Form GI-07.

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, you must show this requirement in the calculation of limited controlled emissions and take this into account in calculating the limited controlled emissions. If you choose to propose to comply with more a stringent limit, you should state this clearly and show the resulting allowed emissions in this calculation.

Step 10. Actual uncontrolled emissions

Calculate the actual emissions by multiplying the emission factor by the actual annual production rate or material usage rate (or whatever units the emission factor is in), and dividing by 2000 pounds per ton.

  • Actual uncontrolled emissions [tons/year] = Emission factor [lb/unit] x Actual production [units/year] x [1 ton/2000 lb]

Step 11. Actual controlled emissions

Calculate the actual controlled emissions by multiplying the actual uncontrolled emissions by (100% - the control efficiency). Use the following formula:

  • Act. controlled emissions [tons/year] = Act. uncontrolled emissions [ton/year] x [100% - Pollution control efficiency]