Storage tank emissions calculations

This method may be used to develop an editable spreadsheet containing detailed emissions calculations for emissions from storage tank operations at your facility. These instructions are used to calculate volatile organic compounds (VOCs) and individual and total hazardous air pollutants (HAPs) emissions. Potential emissions of other pollutants from storage tank operations will also need to be included in the permit application (e.g., emissions from fuel combustion for heating stored materials). Each step in your calculation(s) needs to be clear and easy to follow.

  • Note that certain tanks are insignificant activities under Minn. R. 7007.1300 and it may not be necessary to calculate emissions from these sources. For example, gasoline storage tanks with a combined total capacity of less than 2000 gallons represent an insignificant activity which is not required to be listed in a permit application. Refer to the instructions for Form IA-01 for further information.

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.
  • Storage Tank identification number(s) — Include the identification number of the storage tank (TK#). Obtain this number from Form GI-05C or the appropriate form related to the permit you are applying for, or your existing permit.
  • Heaters, if applicable If there are fuel combusting heaters associated with this tank, indicate the number of heaters, the fuels which can be used, and the total rated heat input of each heater. Be sure to calculate emissions from the heaters as shown on the webpage for External Combustion Units. If the heaters use electric heat, there would be no emissions.
  • Type of Tank — Indicate the type of tank and follow the calculation instructions as shown.

If the tank is a:

Follow the instructions under:

Vertical Fixed Roof Tank

Part I below,  as applicable

Horizontal Fixed Roof Tank

Part I below,  as applicable

Internal Floating Roof Tank

Part II below,  as applicable

External Floating Roof Tank

Part III below,  as applicable

  • Formula/Equation — For each calculation step, the formula and/or equation needs to be available in the spreadsheet cell .
  • Operating limitations — Describe in detail any permit limits you plan to take to restrict your potential-to-emit (production limits, bottlenecks, etc. - see Proposing Synthetic Minor Permit Limits). Attach additional information, as 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  (Limited Emissions).  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.

Emissions Calculation Instructions

The calculations of emissions from storage tanks are complex. Use Tanks 4.09D (or a more recent version) to calculate the VOC and HAPs emissions. TANKS 4.09D can be downloaded from the U.S. Environmental Protection Agency (EPA) Office of Air Quality Planning and Standards (OAQPS) Technology Transfer Network (TTN) bulletin board system through the Internet. The printout from the TANKS program needs to be included in the permit application.

Part I. If your tank is a Fixed Roof Tank (Vertical or Horizontal)

Follow these steps for calculating and documenting the emissions for each fixed roof storage tank at your facility. Generally, each column of your spreadsheet will correlate to a step indicated below. Additional columns can and should be included in the spreadsheet to indicate additional steps or information specific to your tank. See the table below as an example format. This is only an example, and any format displaying the information clearly can be used.
Example Format


Pollutant

Maximum Unlimited Emissions (lb/yr)

Maximum Unlimited Emissions (tpy)

Limited emissions (tpy)

Actual Emissions (tpy)

Proposed Operating Limitations

VOC – Standing loss

 

 

 

 

 

VOC – Working loss

 

 

 

 

 

VOC – Total Loss

 

 

 

 

 

HAP 1 – Standing loss

 

 

 

 

 

Etc.

 

 

 

 

 

Step 1. Pollutant

List each pollutant (VOC, each individual HAP, total HAPs) and whether the calculation is for the standing loss, working loss or total loss.

  • VOC = volatile organic compounds
  • HAPs = hazardous air pollutants – each individual hazardous air pollutant. See EPA's Web site for more information.
  • Total HAPs = All HAPs added together

Step 2. Maximum unlimited emissions, lbs/yr

Document the potential uncontrolled emissions calculated by the TANKS program in pounds per year, for standing losses and working losses for each pollutant. Add them to obtain the total losses.

Step 3. Maximum unlimited emissions, tons/yr

Document the potential uncontrolled emissions in tons per year by dividing Maximum Unlimited Emissions (lb/yr) by 2000 lb/ton, for standing and working losses. Add them to obtain the total losses.

Step 4. Limited emissions

(Skip this item if these calculations are for Registration Permit Option D.)

The Limited Emissions are determined by using the TANKS program and taking into account all proposed limitations on operation of the source. An example of such a limitation might be the amount of tank throughput. Fill in the numbers from the TANKS program for standing and working losses, and add them to obtain the total losses.

Step 5. Actual emissions

If this is an existing tank and historical records exist, determine actual emissions by using the TANKS program and the average of the previous two calendar years of usage data. If this is a new unit or no records exist, use the TANKS program and a reasonable estimate of the tank’s actual throughput. Report actual emissions in tons/year.

Step 6. Operating limitations

Describe the proposed limitations used to calculate the Limited Emissions. Be sure to include all proposed limitations on Form CD-01.

Part II. If your tank is an Internal Floating Roof Tank

Follow these steps for calculating and documenting the emissions for each internal floating roof storage tank at your facility. Generally, each column of your spreadsheet will correlate to each step indicated below. Additional columns can and should be included in the spreadsheet to indicate additional steps or information specific to your tank. See the table below as an example format. This is only an example, and any format displaying the information clearly can be used.
Example Format


Pollutant

Maximum Unlimited Emissions (lb/yr)

Maximum Unlimited Emissions (tpy)

Limited emissions (tpy)

Actual Emissions (tpy)

Proposed Operating Limitations

VOC – Rim Seal loss

 

 

 

 

 

VOC – Withdrawal loss

 

 

 

 

 

VOC – Deck Fitting Loss

 

 

 

 

 

VOC – Deck Seam Losses

 

 

 

 

 

VOC – Total Loss

 

 

 

 

 

HAP 1 – Rim Seal loss

 

 

 

 

 

Etc.

 

 

 

 

 

Step 1. Pollutant

List each pollutant (VOC, each individual HAP, and/or total HAPs) and whether the emissions are rim seal loss, withdrawal loss, deck fitting loss, deck seam loss, or total loss.

Step 2. Maximum unlimited emissions, lbs/yr

Document the potential uncontrolled emissions calculated by the TANKS program for rim seal losses, withdrawal losses, deck fitting losses, and deck seam losses. Add them to obtain the total losses.

Step 3. Maximum unlimited emissions, tons/yr

Document the potential uncontrolled emissions in tons per year by dividing Maximum Unlimited Emissions (lb/yr) by 2000 lb/ton, for all the types of losses. Add them to obtain the total losses.

Step 4. Limited emissions

(Skip this item if these calculations are for Registration Permit Option D.)

The Limited Emissions are determined by using the TANKS program and taking into account all proposed limitations on operation of the source. An example of such a limitation might be the amount of tank throughput. Fill in the numbers from the TANKS program for rim seal losses, withdrawal losses, deck fitting losses, and deck seam losses, and add them to obtain the total losses.

Step 5. Actual emissions

If this is an existing unit and historical records exist, determine actual emissions by using the TANKS program and the average of the previous two calendar years of usage data. If this is a new unit or no records exist, use the TANKS program and a reasonable estimate of the tank’s actual throughput. Report actual emissions in tons/year.

Step 6. Operating limitations

Describe the proposed limitations used to calculate the Limited Emissions. Be sure to include all proposed limitations on Form CD-01.

Part III. If your tank is an External Floating Roof Tank

Follow these steps for calculating and documenting the emissions for each external floating roof storage tank at your facility. Generally, each column of your spreadsheet will correlate to each step indicated below. Additional columns can and should be included in the spreadsheet to indicate additional steps or information specific to your tank. See the table above as an example format. This is only an example, and any format displaying the information clearly can be used.
Example Format


Pollutant

Maximum Unlimited Emissions (lb/yr)

Maximum Unlimited Emissions (tpy)

Limited emissions (tpy)

Actual Emissions (tpy)

Proposed Operating Limitations

VOC – Rim Seal loss

 

 

 

 

 

VOC – Withdrawal loss

 

 

 

 

 

VOC – Deck Fitting Loss

 

 

 

 

 

VOC – Total Loss

 

 

 

 

 

HAP 1 – Rim Seal loss

 

 

 

 

 

Etc.

 

 

 

 

 

 

 

 

 

 

 

Step 1. Pollutant

List each pollutant (VOC, each individual HAP, and/or  total HAPs) and whether the emissions are rim seal loss, withdrawal loss, deck fitting loss, or total loss.

Step 2. Maximum unlimited emissions, lbs/yr

Document the potential uncontrolled emissions calculated by the TANKS program for rim seal losses, withdrawal losses, and deck fitting losses. Add them to obtain the total losses.

Step 3. Maximum unlimited emissions, tons/yr

Document the potential uncontrolled emissions in tons per year by dividing Maximum Unlimited Emissions (lb/yr) by 2000 lb/ton, for rim seal losses, withdrawal losses, and deck fitting losses. Add them to obtain the total losses.

Step 4. Limited emissions

(Skip this item if these calculations are for Registration Permit Option D.)

The Limited Emissions are determined by using the TANKS program and taking into account all limitations on operation of the source you are proposing to comply with in this application. These limitations include limits on the amount of tank throughput, for example. Fill in the numbers from the TANKS program for rim seal, withdrawal, and deck fitting losses, and add them to obtain the total losses.

Step 5. Actual emissions

If this is an existing unit and historical records exist, determine actual emissions by using the TANKS program and the average of the previous two calendar years of usage data. If this is a new unit or no records exist, use the TANKS program and a reasonable estimate of the tank’s actual throughput. Report actual emissions in tons/year.

Step 6. Operating limitations

Describe the proposed limitations used to calculate the Limited Emissions. Be sure to include all proposed limitations on Form CD-01.