Performance of Continuous Emission Monitoring Solutions under a Single-Blind Controlled Testing Protocol

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 a 90% probability of detection (POD) of 3–30 kg CH4/h; 6 of 11 solutions achieved a POD 4/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（Continuous Emission Monitoring，CM）解决方案相比传统泄漏巡检，能够更早地检测天然气基础设施中大量的无组织甲烷泄漏；同时，基于CM解决方案的量化工作已被提议作为基于测量的排放清单的基础。本研究在可控排放设施（排放速率为0.4~6400 g CH₄/h）中开展了单盲测试，模拟了具有挑战性但相较于典型现场工况更为简化的实验条件。本次测试共涵盖11款CM解决方案，包括点式传感器网络以及扫描/成像类监测方案。测试结果显示，在3~30 kg CH₄/h的泄漏速率下，监测方案的90%检测概率（Probability of Detection, POD）得以实现；其中6款方案可达到4 kg CH₄/h级别的POD，不过相关不确定性较高。4款方案的真阳性率超过50%，假阳性率则分布在0~79%之间。共有6款方案可实现排放速率估算。当泄漏速率处于0.1~1 kg/h区间时，各方案的平均相对误差范围为-44%~+586%，单次估算的相对误差则介于-97%~+2077%之间，其中4款方案的不确定性上限超过+900%。当泄漏速率高于1 kg/h时，平均相对误差范围为-40%~+93%，其中2款方案的估算误差处于±20%以内，单次估算的相对误差则分布在-82%~+448%之间。不同CM解决方案之间的性能差异显著，加之检测、检测限以及量化结果均存在较高不确定性，这表明在将相关结果用于内部减排计划或合规性报告之前，需充分了解单款CM解决方案的实际性能表现。