May 31, 2022
Fugitive emissions are emissions from unintentional or intentional release of greenhouse gases (GHG) to the atmosphere. Releases can be accidental, caused by equipment leaks, defective seals or joints, or they can be intentional venting, flaring, or discharging of GHGs. Various sources cite fugitive emissions contribute to approximately 5% of total global GHG emissions, although in the sectors where they are most commonly emitted, fugitives can contribute to more than 50% of a facilities scope 1 and scope 2 GHG emissions. The inclusion of fugitive emissions in a GHG inventory is often overlooked due to the difficulty in monitoring or calculating emissions, however, they should be an important consideration when developing a GHG inventory.
In a GHG inventory, fugitive emissions are treated to be their own category of Scope 1 emission sources.
Scope 1 GHG emission sources.
Three main activities contribute to fugitive emissions:
Across multiple industries, refrigerant usage in mobile or stationary equipment (such as HVAC systems) cause the release of hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulphurhexafluoride (SF6), which are all greenhouse gases under the Kyoto Protocol. Releases of these greenhouse gases may occur during the manufacturing process, from leakage during equipment usage, or from refrigerant disposal at the end of the life of the equipment.
In Oil & Gas, methane (CH4), may be released during exploration, production, transportation, refining, and distribution activities. Methane releases may be unintentional or intentional, with unintentional releases caused by equipment leaks, defective seals, or joints throughout fossil fuel transportation and storage. Intentional releases often occur due to safety reasons surrounding facility design, or intentional venting may also occur when natural gas cannot be used or recovered economically, and thus it is vented instead of being sold or burned.
Similarly to Oil & Gas, methane emissions are released throughout Coal Mining. Coal that is mined is formed over millions of years when biogenic matter is compressed and heated. Throughout this geological process, methane and carbon dioxide (CO2) becomes trapped in the coal formations. The trapped gas is known as seam gas, and this gas generally has a 95-97% pure methane composition. Seam gas is then released during the exploration, mining, storage, transportation, or distribution of coal from both underground and above-ground mines. Once Oil & Gas and Coal Mining activities have ceased, abandoned wells and mines may also continue to emit methane.
The inclusion of fugitive emissions in a GHG inventory is often overlooked, however, fugitive emissions should be an important consideration. The global warming potential (GWP) of CH4, HFCs, PFCs and SF6s are tens to thousands of times more potent than CO2, and thus their impact on climate change is significant. This potency, combined with the volume of unintentional and intentional releases of GHGs in sectors such as Oil & Gas and Coal Mining results in fugitive emissions being one of the largest contributors to GHG’s in these sectors.
Calculating GHG emissions from fugitive sources is challenging due to the difficulty in defining appropriate emission factors, and the difficulty in measuring activity data. Depending on available data, the reporting company may choose to follow a Tier 1, Tier 2, or Tier 3 approach outlined in the 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Volume 2, Chapter 4 to calculate fugitive emissions. Tier 1 approaches require companies choose from global-average emission factors. Tier 2 approaches uses country-specific emission factors from studies, public reports, or measurement programmes. Tier 3 approaches uses facility-specific activity data, and requires direct measurements on a facility-specific basis. In some instances, such as at surface coal mines, it is not yet feasible to collect Tier 3 data. Regardless of the approach taken to report fugitive emissions, by tracking and reporting, organizations can uncover opportunities to mitigate these emission sources. The accuracy of mitigation opportunities can be further refined if Tier 3 data is available for collection.
In SINAI, industry-specific calculation methodologies and emission factors for fugitive emissions calculations have been integrated into SINAI’s inventory module based on IPCC and GHG Protocol guidance. Our models are designed to facilitate the simplification of fugitive emission calculations, particularly in the Oil & Gas and Coal Mining sectors to ensure all emissions sources are captured appropriately in a GHG inventory according to international standards.