Technical overview of changes to British Columbia’s oil and gas methane emissions

2024 National Inventory Report

Over the past decade, many scientific studies have identified a persistent underestimation of oil and gas methane (CH4) emissions. These studies use newer atmospheric measurement techniques and models to derive “top-down” emissions estimates, which are compared with the traditional “bottom-up” inventory estimates that rely on statistical and engineering methods to estimate emissions for individual sources. The bottom-up estimates are derived using various data, including component-level emissions factors and populations, process simulations, metered or calculated volumes of gas vented or flared, etc.

Improvements to the NIR methane emissions estimates

The atmospheric measurement studies have significantly improved our understanding of total oil and gas methane emissions in recent years. In both the 2022 and 2023 editions of Canada’s NIRs of greenhouse gas emissions, Environment and Climate Change Canada described (in the NIR Improvement Plan, chapter 8) the intention to use atmospheric measurement data to improve estimates of oil and gas methane in Canada’s three main oil- and gas-producing provinces: British Columbia (BC), Alberta, and Saskatchewan. The 2024 NIR includes methodological improvements to incorporate source-resolved methane emissions derived from atmospheric measurements for specific sources, including storage tanks, compressors, and unlit flares. Please refer to Annex 3.2 of the NIR for details on the methods used to estimate fugitive oil and gas methane emissions.

Accurately estimating fugitive emissions from oil and gas operations is a challenge. The industry in Canada includes tens of thousands of facilities, hundreds of thousands of wells, and millions of components with the potential to emit. While the 2024 methodological updates represent a significant step forward in improving the accuracy of methane emissions from the oil and gas sector, robust source-resolved atmospheric measurement-based data is only available starting in 2020. To meet time-series consistency requirements in the United Nations Framework Convention on Climate Change (UNFCCC) reporting guidelines, Environment and Climate Change Canada has back-casted the source-level atmospheric measurement-based emissions back to 1990 using facility count and production data. Due to the lack of comparable atmospheric measurement data prior to 2020, the historical oil and gas methane emissions estimates continue to be estimated using traditional quantification methodologies, which are inherently less certain in comparison.

In collaboration with the British Columbia Ministry of Environment and Climate Change Strategy (BC MECCS), Environment and Climate Change Canada has identified potential areas where the historical emissions estimates for BC’s oil and gas industry could be improved. These further improvements will not change the 2020–2022 methane estimates but could affect the relative emissions reductions from the 2012 (federal) or 2014 (BC) baseline. Therefore, the BC oil and gas methane emissions estimates presented in the 2024 NIR are continuing to be reviewed. Preliminary analysis suggests that emissions estimates for natural gas-driven pneumatic devices and equipment leaks may be underestimated, and upward revisions in the years prior to 2020 are anticipated in the 2025 NIR (1990–2023 emissions), pending further data collection and analysis by both governments. BC and Environment and Climate Change Canada will continue to work together on future methane estimates by refining back-casting methods and developing ways to include more measurement data.

BC’s methane emissions progress

Despite these technical estimation issues, the oil and gas industry in BC has consistently been shown to have one of the lowest emissions intensities (emissions per unit of production) in Canada and internationally. This is supported by the recent atmospheric measurements. The 2024 NIR shows a more than 50 percent reduction in methane emissions intensity between 2012 and 2022, while the province’s oil and gas sector experienced an 80 percent increase in production. The expected upward revisions of pre-2020 emissions in next year’s NIR would result in a larger reduction in intensity since 2012. Furthermore, with BC’s target of near elimination of all industrial methane emissions by 2035, progress against the original baseline will be less important. BC continues to support methane measurement to monitor the effectiveness of its methane reduction initiatives.

The Government of Canada looks forward to continuing discussions with technical experts from the provinces and other relevant stakeholders ahead of the 2025 NIR publication.

Overview of the airborne campaign

The Energy and Emissions Research Laboratory (EERL) at Carleton University performed the aerial measurement campaign in BC, funded by the BC and federal governments, from September 11 to October 8, 2021, at 508 distinct sites comprising 601 active facilities and 904 active wells^{Footnote *}. This sample represented 60 percent of the approximately 1,006 active facilities and 10 percent of the 8,995 active wells in the province at that time. The sample also provided a broad representation across the range of unique facility subtypes present in BC, allowing for the creation of a robust inventory. All sites with detected sources were flown at least twice on separate days, one to 10 days apart, where each flight included multiple overlapping passes as necessary to fully cover the facility or previously detected sources. EERL analysis showed that the methane emissions were approximately three times higher than 2021 emissions reported in the 2023 NIR. The analysis also identified that emissions from compressors, tanks, and unlit flares were significant contributors to the underestimation in the NIR.