Estimating Landfill Greenhouse Gas Emissions from Measured Ambient Methane Concentrations and Dispersion Modeling

Since municipal solid waste (MSW) landfills emit significant amounts of methane, a potent greenhouse gas, there is considerable interest in quantifying surficial methane emissions from landfills. The authors propose a new and easier method by which to estimate methane emissions. The technique uses hundreds of ambient air VOC measurements taken within a landfill, as receptors, and solves the standard Gaussian dispersion equations by matrix methods, to determine the methane emission rates at hundreds of locations throughout a MSW landfill. The method was tested on a Central Florida MSW landfill using various scenarios with differing source and receptor locations. Once accurate methane emissions throughout a MSW landfill are determined, they can be used as surrogates for odor emissions to predict downwind odor concentrations via a more sophisticated dispersion model such as ISC, AERMOD or CALPUFF. Other beneficial uses from this research include: determination of existing gas collection system efficiencies, calculation of fugitive greenhouse gas emissions from MSW landfills, and improved landfill gas management. The material in this paper is of interest to scientists, policy makers, landfill managers, and those concerned with global climate change, greenhouse gas inventory, and environmental management practices.