Single-blind detection, localization, and quantification of methane emissions using continuous path-integrated column measurements

Abstract. Path-integrated column measurements with a laser absorption-based measurement system have been used to detect, locate, and quantify methane (CH₄) emissions from a series of single-blind controlled releases with no prior knowledge of timing, locations, or release rates. System performance was evaluated against metrics defined in the Continuous Monitoring Protocol established by the Methane Emissions Technology Evaluation Center (METEC) at Colorado State University. This protocol allows more direct comparison of system performance between disparate measurement technologies. This experiment differs from similar tests where releases were conducted from equipment units at fixed locations at METEC by instead conducting releases at random locations anywhere within the central 0.18 km² of a 0.35 km² test site. The releases were much shorter in duration than those conducted in similar testing at METEC. The system detected 25 of 42 releases, which ranged in metered rate from 0.17 to 2.15 kg/h. The minimum detected emissions rate was 0.22 kg/h, and the system demonstrated a 100 % detection rate for releases ≥0.65 kg/h and average wind speed <5 m/s. The test site was subdivided into 20 boxes (109 × 83 m each), and the correct release box was identified in 9 cases, another 9 detections were localized to an adjacent box, and the remaining 7 were attributed elsewhere within the field. The average estimated emission rate bias was -6.1 %. The 90 % detection limit was 0.89 kg/h, while the wind-normalized detection limit was 0.44 (kg/h)/(m/s).