Measuring methane emissions from a landfill using a cost-effective micrometeorological method

Landfills are one of the largest sources of methane to the atmosphere, yet their emissions are seldom measured. This results in high uncertainties in national emission estimates. We developed a Flame Ionization Detector- based micrometeorological measurement system and tested it at a large municipal landfill in Finland. The technical characteristics of the system allowed use of the eddy covariance method, enabling emission monitoring at a much lower cost than employing a Tunable Diode Laser instrument, which we used as a reference. Combining methane and carbon dioxide flux measurements we were able to estimate the methane generation rate, gas collection efficiency and oxidation rate in the landfill surface layer. We showed that the oxidation fraction may differ significantly from the default value used in the IPCC emission modelling, and that high emission rates were observed in the active deposition areas of the landfill.