The horizontal plane method of fugitive emission rate measurement

The horizontal plane method is a novel method of measuring fugitive emission rates that is based on the mass balance approach. Conventional mass balance approach methods measure concentrations or integrated concentrations of airborne matter across a substantially vertical measurement surface that is substantially perpendicular to the wind flow direction. In contrast, for the horizontal plane method, concentrations or integrated concentrations of airborne matter are measured across a substantially horizontal sampling surface that is substantially parallel to the wind flow direction. This characteristic allows users of the horizontal plane method to sample an entire cross-section of a plume that exceeds the operating ceiling of drones or if there is an operating floor for aircraft. A horizontal plane map may be used to estimate the plan location of individual emission sources. Since sampling is horizontal, there is also the potential to efficiently measure the fugitive emission rate of large areas or the fugitive emission rates of multiple sources over large areas. Optimal conditions to carry out the method include conducting the field work during daytime sunny weather and obtaining the concentration or integrated concentration measurements between an altitude of approximately 110 m and 120 m.A horizontal plane system, which incorporated the horizontal plane method to measure the upper portion of the plume and a conventional mass balance method to measure the lower portion of the plume, was applied at the Vancouver Landfill and a methane emission rate of the landfill of 181 g/s was measured. By comparison, a methane emission rate of 177 g/s was measured using the airborne matter mapping method that had been applied earlier the same afternoon, for a difference of approximately +2.5%. The horizontal plane map that was generated enabled the identification of the estimated location of four areas of the landfill with relatively high emission rates.<i>Implications</i>: Small drones are a low-cost and effective platform for measurement of fugitive emission rates. However, drones are subject to safety regulations that impose an operating ceiling, and this constrains their ability to measure emission rates, especially of large plumes, using available quantification methods. The novel horizontal plane method of fugitive emission rate measurement expands the capabilities of drones by allowing drones to operate within regulatory constraints even if the altitude of a plume exceeds the operating ceiling of drones. The method also provides a map that can be used to estimate the location of individual emission sources.