Fig. 2: Contributions to total methane emissions from Alberta and Saskatchewan’s oil and gas sectors by estimation method.
a Alberta oil and gas inventory from 2023 NIR, b Saskatchewan oil and gas inventory from 2023 NIR, c Alberta oil and gas inventory from 2024 NIR and d Saskatchewan oil and gas inventory from 2024 NIR. Components include: 1) Extrapolation: includes emission estimates for sources taken from detailed inventory studies compiled by Clearstone Engineering Ltd. for the years 2000, 2005, and 2011 and extrapolated for the years without detailed inventory data based on changes in various activity data. 2) Combustion modeling: for natural gas combustion, facility reported fuel gas volumes are multiplied by consumption-weighted, technology specific CH4 emission factors. Fuel consumption volumes for other fuels (e.g., diesel, propane, gasoline, etc.) are multiplied by fuel specific CH4 emission factors. 3) Direct Estimation: includes emission sources that are estimated directly by Environment and Climate Change Canada (ECCC) using facility reported volumetric data and detailed gas composition data. 4) Modeling: includes emission sources that are modeled by ECCC based on annual facility counts, average number of components per facility, component-level emission factors and gas composition data. 5) Atmospheric Measurements: source-resolved emission inventories for AB (2021) and SK (2020 and 2021) by Energy and Emissions Research Laboratory (EERL) derived using aerial survey data are used as the basis to estimate emissions from storage tanks, compressor buildings, unlit flares, engine sheds in AB and SK, and wellheads in SK. As shown by the dashed lines, the large drop in 2020 is the result of regulatory implementations, the COVID-19 pandemic, and changes in industry reporting requirements.
