Long-open-path fixed continuous methane emission monitor

Abstract

There are 100,000’s of oil and gas storage tanks and tank batteries at upstream production sites. These sites have shown to be inadvertent, intermittent, generally unmonitored, high flow rate (flux) methane emitters; their emission rates are poorly quantified. Flux measurements are inhibited by the difficulty to directly access emission sources, instrument limitations and high-cost, and inability to distinguish between unintentional fugitive emission events (leaks) versus routine venting from pneumatic valves and compressors. Novel cost-effective and reliable continuous quantitative methane flux measurement technologies are needed to address these challenges. Methane is a potent greenhouse gas, and emissions from these sites need to be detected and prioritized for repairs based on emission rates. This paper describes a continuous methane emission monitor that combines our easily-installed high-speed laser-based long-open-path sensor, the Remote Emissions Monitor (REM), with a unique and novel fast laser beam scanning mechanism to create “flux planes” along site perimeters. This Enhanced REM (eREM) directly measures and reports emission rates (e.g. scfh) of methane plumes transported through the flux plane at about 1Hz without the need for plume modeling. The inherent temporal resolution enables novel statistical data processing that identifies routine vents and distinguishes them from unintended emissions. The simplicity of design, ease of installation, and minimal maintenance enable economically attractive fast and accurate detection and quantification of methane leakage.