title: Characterization of uncertainty in estimation of methane collection from select U.S. landfills.
abstract: Methane is a potent greenhouse gas generated from the anaerobic decomposition of waste in landfills. If captured, methane can be beneficially used to generate electricity. To inventory emissions and assist the landfill industry with energy recovery projects, the U.S. EPA developed the Landfill Gas Emissions Model (LandGEM) that includes two key parameters: the first-order decay rate (k) and methane production potential (L0). By using data from 11 U.S. landfills, Monte Carlo simulations were performed to quantify the effect of uncertainty in gas collection efficiency and municipal solid waste fraction on optimal k values and collectable methane. A dual-phase model and associated parameters were also developed to evaluate its performance relative to a single-phase model (SPM) similar to LandGEM. The SPM is shown to give lower error in estimating methane collection, with site-specific best-fit k values. Most of the optimal k values are notably greater than the U.S. EPA's default of 0.04 yr(-1), which implies that the gas generation decreases more rapidly than predicted at the current default. We translated the uncertainty in collectable methane into uncertainty in engine requirements and potential economic losses to demonstrate the practical significance to landfill operators. The results indicate that landfill operators could overpay for engine capacity by $30,000-780,000 based on overestimates of collectable methane.
authors.affiliation: Department of Civil, Construction, and Environmental Engineering, North Carolina State University , Campus Box 7908, Raleigh, North Carolina 27695-7908, United States.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Wang
authors.forename: Ajay S
authors.initials: AS
authors.lastname: Nagpure
authors.forename: Joseph F
authors.initials: JF
authors.lastname: DeCarolis
authors.forename: Morton A
authors.initials: MA
authors.lastname: Barlaz
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D004560:Electricity; D008697:Methane / Q000032:analysis*; D008962:Models, Theoretical; D009010:Monte Carlo Method; D062611:Solid Waste; D035501:Uncertainty; D014481:United States; D064091:Waste Disposal Facilities
chemical_list: D000393:Air Pollutants; D062611:Solid Waste; D008697:Methane