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Reporting methane venting emissions: why you should step away from modeling and use a measurement-based approach

According to the IEA[1], 64% of the world’s total methane emissions in 2020 were vented in the atmosphere and is hence the single most important contributing source of Short-Lived Climate Pollutant (SLCP).

In this blog post, we focus on the wide range of vents and discuss why it is worthwhile to apply a measurement-based approach to report methane emissions from venting devices and comply with OGMP 2.0.

Source TypeEmission [kt]Percentage
Fugitive22 78532%
Incomplete-flare3 0384%
Vented46 24564%
Total72 068

Reporting venting emissions starts at Reporting Level 2

Has your company set the ambition to comply with OGMP 2.0? Then you know that one of the main updates compared to the original Framework is that all sources of methane emissions, including emissions from process venting, now must be reported.

The OGMP 2.0 includes 5 Reporting Levels. Reporting emissions from venting devices is already required to reach level 2. More specifically, methane emissions on asset level must be reported, and a distinction between methane emissions categories is required. These categories are different for upstream, and mid-and downstream.

For upstream, these emission categories are:

  • Venting,
  • Fugitive losses.
  • Flaring,
  • Energy / Combustion,
  • Other / Unspecified.

For mid-and downstream, these emission categories are:

  • Fugitive losses,
  • Venting,
  • Incomplete combustion.

OGMP Level 3 compliance

From Reporting Level 3 onwards, venting emissions are defined as a specific source type. For upstream, venting is defined as one of 13 source types. For mid-and downstream, venting is categorized as one of three source types. The below overview shows the different source types.

Source types for upstream for Reporting Level 3-4
Source types for mid-and downstream for Reporting Level 3-4

Generic Emission Factors vs. specific Emission Factors

To quantify the reported emissions in each of the above-mentioned categories, generic emission factors or modeling was used for a long time. To reach OGMP Reporting Level 3, using generic Emission Factors from literature for each component, is sufficient.

However, to comply, you must work towards reaching the OGMP Gold Standard. This means reaching Reporting Level 4 within 3/5 years and reporting per detailed source type by performing direct measurements, including sampling, and by using estimates based on specific Emission Factors.

Which measurement techniques are available on the market to measure venting emissions and determine specific Emission Factors?

Measurement techniques for venting devices

Different vent types ask for different measurement technologies. Before even performing a measurement campaign, we highly recommend creating an inventory of all potential venting devices and components, such as gas-driven controllers and pumps, regulators, vented compressor seals, and pressure safety valves, that emit natural gas to the atmosphere continuously, intermittent, or accidentally.

As an environmental service provider, we often see that gas operators lack a detailed inventory. Especially of their smaller vents. Knowing exactly where your venting devices are, will save your maintenance department valuable time when they perform maintenance or repair activities.

Venting sources included in the asset inventory

Once the inventory is set up, we recommend using a fit-for-purpose approach. For small equipment vents and process and maintenance vents, we use the bagging technique. Bagging is a highly accurate direct measurement technique and is ranked as Best Available Technique in EPA Method 21.

More specifically, we use the Bacharach High Flow Sampler to quantify the methane leak. As the Bacharach is a rather old device and not serviced anymore, The Sniffers has developed its own range of high flow sampler devices, fully third-party qualified, to quantify emissions and support our clients.

The device captures the gas leaking from the vent and determines the mass leakage in kg/hour. In our opinion, this is currently the most accurate method to determine the size of a methane leak at source level and is unique in the market.

Methane emissions from emergency vents are much larger and require other measurement technologies. For these vents, we use flowmeters such as an ATEX anemometer or, in case of inaccessible vents, we could use the quantitative Optical Gas Imaging technique (QL320 combined with the FLIR GFx320 camera) to define the size of the methane leak.

How to determine specific Emission Factors

Identical devices (brand and type) with similar operating conditions can be grouped to determine a common, site-specific emission factor. A statistical number of High Flow Sampling (HFS) quantifications is sufficient to determine a reliable specific emission factor for that type of device.

When quantifying methane emissions during a measurement campaign, devices with high emissions compared to similar devices must be given priority by maintenance to bring the emissions in line with the overall emission characteristic of the device group.

If the working conditions stay identical, you can continue applying the specific EF (Emission Factor). Once circumstances change (operation pressure, gas composition, turnaround or overhaul, etc.), the specific emission factor has to be re-established. All this collected venting emission data will help you and the operational decision-makers to take well-considered decisions on replacements or upgrade investments to strongly reduce or eliminate emissions from these venting devices.

Questions about reporting methane emissions from venting devices?

Contact our experts. We gladly support you.