CH4 emission estimates from an active landfill site inferred from a combined approach of CFD modelling and in situ FTIR measurements
journal contributionposted on 2017-11-24, 15:24 authored by Hannah Sonderfeld, Hartmut Bösch, Antoine P. R. Jeanjean, Stuart N. Riddick, Grant Allen, Sébastien Ars, Stewart Davies, Neil Harris, Neil Humpage, Roland Leigh, Joseph Pitt
Globally, the waste sector contributes to nearly a fifth of anthropogenic methane emitted to the atmosphere and is the second largest source of methane in the UK. In recent years great improvements to reduce those emissions have been achieved by the installation of methane recovery systems at landfill sites, and subsequently methane emissions reported in national emission inventories have been reduced. Nevertheless, methane emissions of landfills remain uncertain and quantification of emission fluxes is essential to verify reported emission inventories and to monitor changes in emissions. Here we present a new approach for methane emission quantification from a complex source such as a landfill site by applying a computational fluid dynamics (CFD) model to calibrated in situ measurements of methane as part of a field campaign at a landfill site near Ipswich, UK, in August 2014. The methane distribution for different meteorological scenarios is calculated with the CFD model and compared to methane mole fractions measured by an in situ Fourier-transform infrared (FTIR) spectrometer downwind of the prevailing wind direction. Assuming emissions only from the active site, a mean daytime flux of 0.83 mg m−2 s−1, corresponding to a spatially integrated emission of 53.3 kg h−1, was estimated. The addition of a secondary source area adjacent to the active site, where some methane hotspots were observed, improved the agreement between the simulated and measured methane distribution. As a result, the flux from the active site was reduced slightly to 0.71 mg m−2 s−1 (45.6 kg h−1), and at the same time an additional flux of 0.32 mg m−2 s−1 (30.4 kg h−1) was found from the secondary source area. This highlights the capability of our method to distinguish between different emission areas of the landfill site, which can provide more detailed information about emission source apportionment compared to other methods deriving bulk emissions.
We thank NERC for their funding (NE/K002465/1 and NE/K002570/1) as part of the Greenhouse gAs Uk and Global Emissions (GAUGE) project. For technical and logistical support, we would like to thank the team of Viridor on-site. Thanks to Andrew Brunton and John Naylor from Ground-Gas Solutions for providing data from their survey of the landfill site. We would like to thank David Hodgetts from the School of Earth and Environmental Sciences, The University of Manchester, for providing the lidar survey data. From the School of Chemistry at the University of Bristol, we would like to thank James C. Matthews, Matthew D. Wright, Damien Martin and Dudley Shallcross for conducting the tracer release experiment. Many thanks to Thorsten Warneke and Hella van Asperen from the Institute of Environmental Physics (IUP), University of Bremen, for their advise on the deployment of the FTIR. We also thank Peter Somkuti for processing the meteorological data. This research used the ALICE High Performance Computing facility at the University of Leicester.
CitationAtmospheric Measurement Techniques, 2017, 10, pp. 3931-3946
Author affiliation/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Chemistry
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