A Process-Based Greenhouse Gas (GHG) Inventory Model for Landfill CH4
Emissions Inclusive of Seasonal Soil Microclimate and CH4 Oxidation
Jean Bogner (’69), Dept. Earth & Environmental Sciences (EAES), Univ. Illinois at
Chicago (UIC), Chicago, IL
Kurt Spokas, Agricultural Research Service-USDA, St. Paul, MN
Jeffrey Chanton, Florida State University, Tallahassee, FL
Margaret Corcoran, Graduate Student, EAES, UIC, Chicago, IL
Methane (CH4) is a potent GHG, with landfills currently estimated to be the 3rd largest
source of anthropogenic CH4 in the U.S. after natural gas leakages and ruminant
animals. Current IPCC (Intergovernmental Panel on Climate Change) national GHG
inventory models for landfill CH4 emissions based on theoretical CH4 generation have
high uncertainties and lack comprehensive field validation. Moreover, literature over
the last decade has emphasized that the major factors controlling landfill CH4 emissions
are the presence of engineered gas extraction, gaseous transport rates as affected by the
thickness and physical properties of cover soils, and microbial CH4 oxidation in cover
materials as a function of seasonal soil microclimate. Therefore we developed and
field‐validated an annual inventory model for California landfill CH4 emissions that
incorporates site‐specific cover soil properties and soil microclimate modeling coupled
to 0.5° scale global climatic models. Based on 1‐D diffusion with CH4 oxidation rates
scaled to temporal soil temperature and moisture [2.5-cm depth increments; 10-min.
time increments], CALMIM (California Landfill Methane Inventory Model) is a JAVA
tool which models a typical annual cycle for CH4 emissions from site‐specific daily,
intermediate, and final landfill cover soil properties. This new approach, which is
compliant with IPCC “Tier III” criteria, has been field‐validated at two California sites
(Monterey County; Los Angeles County), with limited field validation at three
additional California sites. CALMIM accurately predicts soil temperature and moisture
trends with emission predictions within the same order of magnitude as field
measurements, indicating an acceptable initial model comparison in the context of
published literature for small-scale CH4 emission measurements spanning 7 orders of
magnitude. In addition to default values for inventory purposes, CALMIM permits
user‐selectable parameters and boundary conditions where site-specific data exist.
Current project work is focusing on international field validation and structural
improvements. CALMIM is freely available at
www.ars.usda.gov/services/software/download.htm?softwareid=300.
For more information, please consult the following publications:
Spokas, K., Bogner J., and Chanton, J., A Process-Based Inventory Model for
Landfill CH4 Emissions Inclusive of Soil Microclimate and Seasonal Methane
Oxidation, J. Geophysical Research-Biogeosciences, 116: paper G04017, 19 p. (2011).
Bogner, J., Spokas, K., and Chanton, J., Seasonal Greenhouse Gas Emissions
(methane, carbon dioxide, nitrous oxide) from Engineered Landfills: Daily,
Intermediate, and Final California Landfill Cover Soils, J. Environ. Quality 40:10101020 (2011).
Spokas, K., and Bogner, J., Limits and dynamics of methane oxidation in
landfill cover soils, Waste Management 31:823-832 (2011).