Emission quantification using the tracer gas dispersion method: The influence of instrument, tracer gas species and source simulation

Abstract

The tracer gas dispersion method (TDM) is a remote sensing method used for quantifying fugitive emissions by relying on the controlled release of a tracer gas at the source, combined with concentration measurements of the tracer and target gas plumes. The TDM was tested at a wastewater treatment plant for plant-integrated methane emission quantification, using four analytical instruments simultaneously and four different tracer gases. Measurements performed using a combination of an analytical instrument and a tracer gas, with a high ratio between the tracer gas release rate and instrument precision (a high release-precision ratio), resulted in well-defined plumes with a high signal-to-noise ratio and a high methane-to-tracer gas correlation factor. Measured methane emission rates differed by up to 18% from the mean value when measurements were performed using seven different instrument and tracer gas combinations. Analytical instruments with a high detection frequency and good precision were established as the most suitable for successful TDM application. The application of an instrument with a poor precision could only to some extent be overcome by applying a higher tracer gas release rate. A sideward misplacement of the tracer gas release point of about 250m resulted in an emission rate comparable to those obtained using a tracer gas correctly simulating the methane emission. Conversely, an upwind misplacement of about 150m resulted in an emission rate overestimation of almost 50%, showing the importance of proper emission source simulation when applying the TDM.

Methodologies for measuring fugitive methane emissions from landfills – A review

“…In order to obtain a good mix of tracer gas and CH 4 , measurement or sampling campaigns have to be executed at a sufficient distance away from the landfill (e.g. Mønster et al, 2014;Delre et al, 2018). Misplacing the tracer gas can result in significant under-or overestimation of the emission, while the required measuring distance depends on the physical size of the source, atmospheric conditions and the topography between the landfill and the measurement/sampling point (e.g.…”

“…Misplacing the tracer gas can result in significant under-or overestimation of the emission, while the required measuring distance depends on the physical size of the source, atmospheric conditions and the topography between the landfill and the measurement/sampling point (e.g. Fredenslund et al, 2019b;Rees-White et al, 2019;Delre et al, 2018;Taylor et al 2016).…”

“…Piccot et al (1996) and Hensen and Scharff (2003) used tracer gas measurements to obtain accurate information about dispersion conditions during their measurement campaign, thus improving the dispersion model in use. The advantages and limitations of the CRDSbased instrument have been explored and compared recently with simultaneous FTIR measurements (Delre et al, 2018;Mønster et al, 2014). Foster-Wittig et al (2015a), for instance, published a study involving tracer gas dispersion measurements on a large number of US landfills, including suggestions for using data quality criteria for filtering measurements for downwind traverses where tracer and CH 4 were not significantly mixed.…”

“…An additional disadvantage is that measurements are usually taken in hours (2-6 hours) or over a few days, and thus the temporal variation of landfill gas emission can be a challenge to capture. Recent and current research focuses on method validation (Fredenslund et al, 2019b;Matacchiera et al, 2019;Delre et al, 2018;Mønster et al, 2014) and the establishment of quality criteria for data processing ( Fredenslund et al, 2019b;Foster-Wittig et al, 2015a).…”

On-site and ground-based remote sensing measurements of methane emissions from four biogas plants: A comparison study

“…Total CH4 emission rates from the biogas plants were determined using a tracer gas dispersion method (TDM) (Delre et al, 2018;Mønster et al, 2015Mønster et al, , 2014Yoshida et al, 2014). The TDM involves the continuous release of a gaseous tracer combined with downwind measurements of atmospheric CH4 and tracer gas, performed while traversing the plume and using a mobile analytical platform.…”