Comparison of models for predicting landfill methane recovery. Final report.

Landfill methane models are tools used to project methane generation over time from a mass of landfilled waste. These models are used for sizing landfill gas (LFG) collection systems, evaluations and projections of LFG energy uses, and regulatory purposes. The objective of this project was to select various landfill methane models and to provide a comparison of model outputs to actual long-term gas recovery data from a number of well managed and suitable landfills. Another objective was to use these data to develop better estimates of confidence limits that can be assigned to model projections. This project assessed trial model forms against field data from available landfills where methane extraction was maximized, waste filling history was well-documented, and other pertinent site information was of superior quality. Data were obtained from 18 US landfills. Four landfill methane models were compared: a zero-order, a simple first order, a modified first order, and a multi-phase first order model. Models were adjusted for best fit to field data to yield parameter combinations based on the minimized residual errors between predicted and experienced methane recovery. The models were optimized in this way using two data treatments: absolute value of the differences (arithmetic error minimization) and absolute value of the natural log of the ratios (logarithmic error minimization).

Final;.