Energy Institute, Colorado State University, Fort Collins, Colorado 80524, United States.
BPX Energy, Denver, Colorado 80202, United States.
Environ Sci Technol. 2023 Apr 11;57(14):5794-5805. doi: 10.1021/acs.est.2c09235. Epub 2023 Mar 28.
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 CH/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 a 90% probability of detection (POD) of 3-30 kg CH/h; 6 of 11 solutions achieved a POD < 6 kg CH/h, although uncertainty was high. Four had true positive rates > 50%. False positive rates ranged from 0 to 79%. Six solutions estimated emission rates. For a 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%, and 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 were from -82% to +448%. The large variability in performance between CM solutions, coupled with highly uncertain detection, detection limit, and quantification results, indicates that the performance of individual CM solutions should be well understood before relying on results for internal emissions mitigation programs or regulatory reporting.
连续排放监测 (CM) 解决方案有望比传统的泄漏调查更早地检测到天然气基础设施中的大量逸散甲烷排放，并且 CM 解决方案的量化已被提议作为基于测量的清单的基础。本研究在受控释放设施（从 0.4 到 6400 g CH/h 的释放）中进行了单盲测试，复制了具有挑战性但比典型现场条件简单的条件。测试了 11 种解决方案，包括点传感器网络和扫描/成像解决方案。结果表明，3-30 kg CH/h 的检测概率 (POD) 为 90%；11 种解决方案中有 6 种 POD < 6 kg CH/h，尽管不确定性很高。其中 4 种具有 > 50%的真实阳性率。假阳性率在 0 到 79%之间。6 种解决方案估算了排放速率。对于释放速率为 0.1-1 kg/h 的情况，解决方案的平均相对误差范围为 -44%到 +586%，其中有 6 个解决方案的单个估计值介于 -97%到 +2077%之间，4 个解决方案的上不确定度超过+900%。在 1 kg/h 以上，平均相对误差为 -40%到 +93%，有两个解决方案在±20%范围内，单个估计值的相对误差为 -82%到+448%。CM 解决方案之间的性能差异很大，加上检测、检测限和量化结果的高度不确定性，表明在依赖结果用于内部排放缓解计划或法规报告之前，应充分了解单个 CM 解决方案的性能。
