Industrial Methane Measurement Conference - Abstract

Abstract Information :

Satellite observations and surface measurements are key elements for estimating methane CH4 emissions through atmospheric inversions. Both elements are critical for building observation-based monitoring systems for methane emission fluxes. Constraining methane fluxes is particularly important for fossil fuel industries, such as oil, gas and coal. Together, these three industries emit one third of global anthropogenic CH4 and are the most important fossil fuel sources. This study presents results of global atmospheric inversions and compares them to national reports and other emission inventories. Results show that inversions tend to estimate higher CH4 emissions compared to national reports of oil-and-gas-producing countries like Russia, Kazakhstan, Turkmenistan and those located in the Arabic Peninsula. This difference might be partially explained since ultra-emitting events, consisting of large and sporadic emissions greater than 20 tCH4 per hour, are not considered by emission inventories. Ultra-emitters are especially important in some countries, such as Kazakhstan and Turkmenistan, where estimated ultra-emitter emissions are comparable 1.4 Tg yr-1 to total fossil fuel emissions reported in their national inventories 1.5 Tg yr-1 and to half on average of the values reported in the other inventories that we analyzed. This study also considers emissions derived from regional inversions using S5P-TROPOMI atmospheric measurements at the scale of extraction basins for oil, gas and coal. Here, we assumed that those basins are already counted as part of the national CH4 budgets from in-situ-driven and GOSAT-driven inversions. Two coal basins, one in the USA and one in Australia, were considered. Also, six major oil and gas basins 3 in the USA, 2 in the Arabian Peninsula, and 1 in Iran were considered as specific areas where many individual wells and storage facilities are concentrated. Averaged emissions 2019-2020 from the Bowen basin in Australia are greater than 2017 emissions estimated by inversions. For the USA, emissions from all basins analyzed, account for 60 of total USA fossil fuel emissions estimated by inversions. For oil and gas, a basin encompassing four of the highest oil-producing fields in the world comprising Iraq and Kuwait represents 38 of the total fossil emissions estimated by inversions for the Arabian Peninsula. Lastly, the basin estimation for Iran 2.5 TgCH4 represents 68 of fossil fuel emissions from inversions and 59 of independent inventories. Given the important role of the oil, gas and coal sectors to global anthropogenic emissions of CH4, our synthesis allows interpreting the main apparent differences between a large suite of recent emission estimates for these sectors.