Methane emissions from Icelandic landfills - A comparison between measured and modelled emissions

This study compares methane (CH₄) emissions from five Icelandic landfills, quantified using tracer gas dispersion to modelled emission rates using the IPCC FOD model. The average CH₄ emission rates measured from the investigated landfills were 475.4 kg CH₄ h⁻¹ (Álfsnes landfill), 32.5 kg CH₄ h⁻¹ (Fíflholt), 40.8 kg CH₄ h⁻¹ (Gufunes), 9.8 kg CH₄ h⁻¹ (Kirkjuferjuhjáleiga) and 78.4 kg CH₄ h⁻¹ (Stekkjarvík). At three of the landfills (Álfsnes, Fíflholt and Kirkjuferjuhjáleiga), the modelled emission was higher than the measured emission by factors ranging from 1.1 to 4.8, neglecting any CH₄ oxidation in the cover soils. Even though CH₄ oxidation might play a role at some of the investigated landfills, and thus reduce the gap between modelled and measured emissions, it is likely that the model overestimated CH₄ generation due to uncertainties in input model parameters. Assuming that the measured emissions at the five landfills are representative of all the waste disposed in Iceland from 2007 to 2016, the measured emission should be extrapolated to 817 kg CH₄ h⁻¹, which is relatively close to the modelled national emission of 936 kg CH₄ h⁻¹ in 2017. This study showed that the application of the IPCC FOD model at national level is appropriate for estimating landfill CH₄ emissions in Iceland. CH₄ emissions from landfills in Iceland can be reduced by expanding or implementing gas collection or biocover systems for optimised microbial oxidation.