Use of seasonal parameters and their effects on FOD landfill gas modeling.

Abstract

Temporal and spatial variations in landfill gas generations and emissions have been observed and reported by others. Real-time gas data between 2008 and 2014 from a municipal landfill located in a cold, semi-arid climate were consolidated to fit a linear-interpolated form of LandGEM. Seasonal variations in gas collection were observed in the landfill. LandGEM's default decay rate k was not applicable for this Canadian landfill due to significant overestimation (32.2% error). Optimal seasonal k and Lo collection parameters had 8.1% error compared to field data, compared to 8.3% error using optimal annual parameters. The optimal kwinter was 0.0118year-1 and the ksummer was 0.0141year-1 (14.7% difference), with a corresponding Lo of 100.0m3/Mg which changed negligibly between the sets. Three pseudo-second order iterative methods were considered, and evaluated using RSS and generation parameters in the literature. A simple application study was conducted using LFGcost-Web, and found the increased precision of seasonal k's resulted in negligible differences with annual optimized k. The default parameters overestimated the net present worth by 12-155% for three of the four common LFG energy projects.