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Landfill Gas Yield (LandGEM v3.03)

RNG feedstock · EPA first-order decay · 40 CFR 60 Subpart XXX/Cf applicability

LandGEM v3.03
Estimates annual landfill methane generation for the year of interest, peak-year rate, captured CH₄ available for RNG upgrading, and NMOC mass flux for 40 CFR 60 Subpart XXX/Cf applicability. Implements the first-order decay summation Q_CH4 = Σ k·L₀·(M_i/10)·e^(−k·t_ij) per EPA-600/R-05/047. Note: LandGEM v3.1 (Dec 2024) supersedes v3.03 for inventory submittals — see disclaimer.

Waste Mass & Timeline

Mg/yr
year
year
year
years

Model Preset & Kinetics

1/yr
m³ CH₄/Mg
%

NMOC, Collection & GWP

ppmv
595 ppmv = AP-42 no-codisposal default. Use 4000 ppmv for legacy codisposal sites.
%
AP-42 §2.4 typical range 60–85% for well-managed GCCS.
—
29.8 = IPCC AR6 default; 28 = AR5 (legacy GHGRP).

Engineering Basis

  • EPA LandGEM v3.03 (EPA-600/R-05/047, May 2005) first-order decay summation, 10 sub-batches/yr.
  • Defaults: CAA Conv. k=0.05, L₀=170 m³/Mg (NSPS/EG applicability); AP-42 Conv. k=0.04, L₀=100 (inventory).
  • 40 CFR 60 Subpart XXX/Cf applicability trigger: design capacity ≥ 2.5 Mt waste AND NMOC ≥ 34 Mg/yr → GCCS required.
  • Captured CH₄ feeds the upgrading train (PSA / membrane / amine) sized in subsequent RNG calculators.
  • NMOC mass = LFG vol × ppmv × ρ_NMOC (M=86.18 g/mol AP-42 default). CH₄ HHV = 1010 BTU/scf (GPA 2145).
  • Currency note: LandGEM v3.1 (EPA/600/B-24/160, Dec 2024) and AP-42 §2.4 May-2025 update use GHGRP §98.343 eq. HH-1 (DOC-based) — use v3.1 for current EPA inventory work, this calc for NSPS applicability.

Learn the Theory

Understand landfill gas generation, waste composition decay models, methane yield estimation, and RNG pathways

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