Continuous emission monitoring (CM) solutions promise to detect large fugitive methane emissions in natural gas infrastructure sooner than traditional leak surveys, and quantification by CM solutions has been proposed as the foundation of measurement-based inventories. This study performed single-blind testing at a controlled release facility (release from 0.4 to 6400 g CH4/h) replicating conditions that were challenging but less complex than typical field conditions. Eleven solutions were tested, including point sensor networks and scanning/imaging solutions. Results indicated 90% probability of detection (POD) of 3-30 kg CH4/h; 6 of 11 solutions achieved POD >50%. False positive rates ranged from 0 to 79%. Six solutions estimated emission rates. For release rate of 0.1-1 kg/h, the solutions' mean relative errors ranged from -44% to +586% with single estimates between -97% and +2077%, with 4 solutions' upper uncertainty exceeding +900%. Above 1 kg/h, mean relative error was -40% to +93%, with two solutions within 20%, and single-estimate relative errors from -82% to +448%. The large variability in performance between CM solutions, coupled with highly uncertain detection, detection limit, and quantification results, indicate that the performance of individual CM solutions should be well understood before relying on results for internal emissions mitigation programs or regulatory reporting.
Performance of continuous emission monitoring solutions under single-blind controlled testing protocol - Supplementary Information
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Comprehensive reports on the performance of solutions
Report(PDF): Each report summarizes the demography of experiments performed to test a solution, the meteorological conditions during the experiments, and the performance of the solutions. To assess performance, metrics such as probability of detection, emission source localization, and emissions quantification established by the testing protocol were evaluated. Data column header definition(XLSX): Explains the information captured in each column of a solution's data table. Data(XLSX): Each data table contains both controlled releases and detection reports paired to form various classifications for a solution. Data table rows represents either true positive, false positive, or false negative detection classifications. A reported detection successfully paired with a controlled release was classified as a true positive detection. A reported detection which remained unpaired was classified as a false positive detection, while a controlled release which remained unpaired was classified as a false negative. Other excluded data make up the remaining rows of the data table.