A model for the accurate estimation of methane emissions in landfills

Landfills are one of the major sources of methane (CH4) emissions. Prediction of CH4 emissions from landfills is important in estimating power generation potential and greenhouse gas (GHG) emissions from landfills. The most widely used landfill gas (LFG) models developed based on the first order decay (FOD) reaction do not take into account changing waste composition and landfill site conditions in methane estimations. The aim of this study was therefore to develop a LFG model for estimation of methane emissions from landfills in Lagos metropolis. Field investigations were carried out to determine waste composition, waste disposal rates and site conditions relevant for methane emissions estimation. Waste composition studies were conducted and waste fractions were divided into rapidly, moderately and slowly degrading. The output of the model was verified with the US EPA Landfill Gas Emission model (Land GEM). Results revealed maximum CH4 emissions estimated occurred at the end of landfill’s closure. Methane generation potential () and methane generation rate () parameters were dependent on waste composition and site conditions. Model verification also showed methane emissions peaked at the end of landfill’s closure for both models and variation in modelling parameters by Land GEM model resulted in significant change in methane emissions.Keywords: Methane emissions, Landfills, Municipal solid waste, landfill gas, Land GEM mode