Coauthors include Vinaros experiment participants. * Fugitive methane emissions from natural gas facilities offer a significant leverage to reduce greenhouse gas emissions. We present the results of a campaign in which ten methane emission quantification technologies were used to measure 17 blind controlled release experiments at an inert compressor station (representative of a midstream site) in 2021. The exercise aimed at comparing the performance of a variety of top-down and bottom-up techniques, including mobile, ground-based, and handheld monitoring approaches, to quantify methane (CH4) emissions at the site-level, and to assess factors controlling the performances of the measurements systems. The controlled releases covered a wide range of situations, such as different flow rates (from 0.01 kg/h to 50 kg/h), release heights (ranging from 1 m to 28 m), and different types of gas exit. Overall, the quantification lower limit for all techniques probably lies between 0.01 kg/h and 0.1 kg/h. The top-down techniques relying on atmospheric dispersion over distances of several meters or more generally slightly overestimate the emission rates, and were all limited at the lowest wind speed. Most techniques performed well at 0.1 kg/h but exhibited large discrepancies when trying to quantify the 0.01 kg/h release. Tracer and Lidar techniques were found to deliver estimates very close to the actual emission rates with average absolute values of relative errors below 50% on more than two-thirds of releases. The bottom-up handheld OGI techniques underestimate the emission rates, possibly due to the constraints on measurement operation. Besides, most techniques have always been reportedly correct within an order of magnitude of the controlled release rate. The assessment of performances are also associated with deployment constraints. As performances are strongly technique-dependent, and new protocols are needed to reconcile these bottom-up (source-level) and top-down (site-level) quantification. We present a pathway toward reconciling bottom up estimates based on emission factors, top down site level quantification, and inventories.
Topic : Theme 2: State of play in integrated approaches for advanced GHG emission estimates and the way forward to operational services.
Reference : T2-B22
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