Assessing the progress of the performance of continuous emission monitoring solutions under single-blind controlled testing protocol

Recent regulatory spotlight on continuous emissions monitoring (CEM) and the rapid development of CEM solutions has demanded the characterization of solutions performance through regular, rigorous testing using consensus test protocols. This study is the second known implementation of such protocol involving single-blind controlled testing of 10 CEM solutions. Controlled releases of rates (6 to 7100) g CH4/h over durations (0.4 to 10.2) hours under wind speed range of (0.7 to 9.9) m/s were conducted for 11 weeks. Results showed that 4 solutions achieved minimum detection limits (MDLs) within tested emission rate range with all 4 solutions having both the lowest MDLs (3.7 [3.0, 5.2] kg CH4/h to 6.1 [3.7, 17.1] kg 11 CH4/h) and FP rates (9.2% to 15.4%) indicating efforts at balancing low sensitivity with low FP rate. Quantification results showed wide individual estimate uncertainties with emissions underestimation and overestimation by factors up to > 15 and 97 respectively. Three solutions had > 80% of their estimates within a factor of 3 of actual rates for controlled release in the ranges of (0.1 – 1] kg CH4/h and >1 kg CH4/h respectively. Relative to the study by Bell et al., current solutions performance, as a group, generally improved majorly due to solutions from the study by Bell et al. that retested. This result highlights the importance of regular, quality testing to the advancement of CEM solutions for effective emissions mitigation.