07 December 2010
Posted in Center Information
The primary components of LFG are methane (50-60%) and carbon dioxide (40-50%), both potent greenhouse gases (GHGs). Although fugitive emissions of LFG poses a threat to the environment, if managed properly LFG is a valuable energy resource, with fuel value of 18-22 MJ/m3 (Spokas et al., 2006). A major challenge in planning and designing a landfill gas to energy (LFGTE) facility is the uncertainty in LFG generation model predictions.
In this investigation, it was found that the optimum method to estimate LFG model parameters is to determine methane generation potential using disposed MSW composition and laboratory component specific methane potential values. For five Florida case-study landfills L0 varied from 56 to 77 m3/Mg; k varied from 0.04 to 0.11 yr-1 for the statistically significant traditional landfills and was 0.10 yr-1 for the wet-cell. Model predictions of LFG collection rates were on average lower than actual LFG collected. Average collection efficiencies were calculated based on measured LFG collected and modeled LFG generation, and were found to vary from 19% to 64% for the case study landfills. The uncertainty (Coefficient of Variation) in modeled LFG generation rates varied from ±17% to ±30% while landfills were open, ±9% to ±18% at end of waste placement, and ±16% to ±203% fifty years after waste placement ended. This information can be used to estimate uncollected generated LFG in the past and to predict future LFG generation potential with better confidence.