ESTIMATION OF LANDFILL GAS PRODUCTION

Abstract

Landfills accepting biodegradable organic waste produce significant amounts of methane richlandfill gas. Landfill gas, or LFG, constitutes approximately equal quantities of methane andcarbon dioxide. The global emissions of methane from landfills are estimated to be about 10%oftotal anthropogenic emissions. Methane, a greenhouse gas, has a global warming potential(GWP) 21 times that of carbon dioxide over a laO-year time horizon. Therefore, control ofmethane from anthropogenic sources could substantially mitigate global warming. Consideringthese factors, there is renewed interest in controlling methane emissions from landfills.Methane emissions from landfills can be controlled by extracting LFG for energy recovery,passive venting and flaring, or by modifying the landfill cover to enhance passive oxidation ofmethane to carbon dioxide. To design any of the LFG control techniques prior knowledge of theamount of gas available is necessary.LFG production is site specific and depends on factors such as climatic conditions, wastecharacteristics, spatial heterogeneity, age of landfill, geometry of the landfill etc. The currenttechniques used to estimate LFG production are: theoretical calculations, generation models,experimental studies, LFG pumping tests and direct flux measurement. This paper discusses theadvantages and disadvantages in using these methods to estimate LFG production. The paperconcludes with a newly developed method at the University of Calgary, Canada to estimate LFGproduction. The method incorporates a geostatistical technique and a l-D numerical modelwithin a Geographic Information System (GIS).