Methods for Estimating Emissions from Tanks


PTAC is seeking a proposal to execute a project that will determine an appropriate testing, measuring or monitoring method, and provide updated emission factors for determining emission rates from uncontrolled, fixed roof liquid storage tanks in the upstream oil and gas industry.


Recent studies have suggested that tank emissions are a large percentage of vented emissions from upstream oil and gas facilities, and that this emission source is being under-reported to the AER. Tank emissions can be categorized as venting or fugitive emissions. Venting emissions are defined as intentional emissions that have been designed to occur. Emissions associated with tanks that are designed to vent to the atmosphere (uncontrolled tanks) are considered venting emissions and the target of this study. Fugitive emissions, like leaks, occur on tanks that are tied into a control or conservation system and have not been designed to occur. Fugitive emissions from controlled tanks are not the focus of this study.

There is evidence suggesting that the accuracy of current methods for estimating methane emissions from tanks in the upstream oil and gas industry is insufficient. Current methods for estimating tank emissions are provided in Directive 017 and Manual 15, and include:

  • Developing a gas-in-solution (GIS) factor based on periodic testing (involved taking a pressurized sample and sending to the lab to determine the amount of gas in solution);
  • Using a “rule of thumb” to estimate GIS based on the amount of oil production; or

Calculating emissions using a bubble-point pressure correlation (Vazquez – Beggs) where appropriate.

Project Scope

The scope of the project should focus on relevant measurement or monitoring techniques that can be used to determine methane emissions from tanks. This project should help improve the understanding of the magnitude of emissions from production tanks (to improve provincial-wide emissions inventories), and also provide alternative methods or techniques to estimate tank emissions.


The project proposal should include a clear description on how each of the following deliverables will be completed:

  1. Field program design plan – design and execute a field sampling program to determine methane emissions from controlled tanks. The field program should be designed to cover a statistically relevant sample size, and to be able to provide:
    1. Quantification of the volume or flow rate of gas being vented from tanks (m3 gas)
    2. Determination of the methane concentration of the gas stream (% methane)
    3. An emission factor or method that can be used to estimate methane emissions from uncontrolled tanks
  2. Final Report – Prepare a report that:
    1. summarizes the data collected in the field,
    2. discusses the performance, limitations, and accuracy of the measurement or monitoring technology,
    3. provides a statistically relevant emission factor, or method for estimating methane emissions from tanks. The report should detail the methodology used to derive the corresponding values; and
    4. Compares the results to one of the existing methods (i.e. rule of thumb).

It is anticipated that there will be ongoing informal communication with the PTAC and the technical steering committee throughout the project. The proposal should include components for each stage with milestones, the project schedule, proposed costs and relevant expertise of the applicant’s proposed team.

Proposal Outline

The requested proposal should contain a very short description of the PTAC project and scope of work, CV or statement of qualifications and short excerpts of reports written by the applicant. The proposal document, which should be no more than 5 pages in length, addressing the following elements by the deadline stated below:

  • Scope of work
  • Deliverables
  • Budget and execution schedules
  • Personnel assigned to the project
  • Qualifications
  • Disclosure of co-funding agreements or partnerships
  • Requested payment schedule, if any.
  • Description of measurement or monitoring technology, including:
    • Stage of development (TRL 1-9)
    • Previous lab/controlled/field testing performance results (accuracy, range of flows, if methane concentration can be determined using the method, limitations)

Proposals should be submitted online using the following form: Application Form

RFP Schedule

April 14, 2021          RFP issued
May 16, 2021           Deadline for submission to PTAC
June 1, 2021            Proposal selected by ARPC

Selection Process

PTAC has formed a Steering Committee for this project composed of industry stakeholders with relevant expertise. PTAC will facilitate Steering Committee proceedings but will not be a decision-maker.

All submitted proposals will be provided to the Steering Committee for review. The Steering Committee will determine if proposals meet the requirements herein and provide an overall ranking based on Contractor qualifications and on proposal quality. The Steering Committee will make the final decision.

Once a selection of the best proposal according to the Steering Committee has been made, all submission contacts will be notified by email of the regarding the outcome of their individual proposal. The project final report will be shared on the PTAC website upon completion of the project.

Contact Information

Lorie Mayes
Tel.: 403-218-7707
Email: [email protected]

Tannis Such
Tel.: 403-218-7703
Email: [email protected]