Nevada Statewide Greenhouse Gas Emissions Inventory and Projections, 1990 to 2030
Nevada Statewide Greenhouse Gas Emissions Inventory and Projections, 1990 to 2030
7.2 Solid Waste
It is estimated that landfill waste continues to emit CH4 for decades after its initial emplacement.
Emission rates from landfills follow a first order decay model, with ever-diminishing levels of CH 4 being
released for decades. Depending on the climate, the rate of decay of the organic matter in landfills can
change (arid climates such as Nevada's means landfill waste takes longer to decay). Therefore, in order
to calculate annual emissions from landfills it is not only important to estimate the current waste in
place (WIP), (i.e., the amount of waste since the beginning of landfill activity), but also the relative
amount of waste that has been historically emplaced on an annual basis.
Landfill waste in this report is divided into two categories, municipal solid waste (MSW) and industrial
landfill waste. MSW is solid waste that originates from residential, commercial, and institutional
sources. Industrial waste is non-hazardous solid waste generated at industrial plants and construction
sites, and from demolition debris. MSW and industrial waste are stored in the same landfills in Nevada
but are assumed to have different organic fractions; that is, the percentage of organic matter in their
waste that will decompose to form CO2 and CH 4. The EPA assumes that MSW has a 65 percent organic
fraction and that industrial waste has an 11 percent organic fraction. These assumed organic fractions
are then applied to Nevada's ratio of MSW to industrial waste (Nevada's ratio is assumed to be different
from the national average) and the CH4 producing capacity of Nevada's industrial landfill waste can be
calculated.31
7.2.1
Historical Emissions
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Nevada's solid waste emissions in 2013 were 1.449 MMTCO2eq. This represented roughly 4 percent of
the state's gross CO2eq emissions. Solid waste emissions peaked in 2011 at 1.915 MMTCO2eq. That
emissions peaked is due to the installation of gas-recovery systems. The installation of gas-recovery
systems in Nevada did not occur until the late 1990s (the first landfill flaring activity began in 1998 and
the first LFGTE project began operating in 2012). The installation of this equipment significantly reduces
the GWP of Nevada's landfills as it effectively converts the CH 4 fraction of the landfill's emissions into
CO2.32 Table 7-2 lists historical solid waste emissions estimates. Figure 7-1 shows the historical
emissions from 1990 to 2013; in the figure actual emissions are solid and avoided emissions from gas-
recovery systems are the dashed areas at the top of the figure.
30 EPA (1993) Anthropogenic Methane Emissions in the United States, Estimates for 1990: Report to Congress, U.S.
Environmental Protection Agency, Office of Air and Radiation. Washington, D.C. EPA/430-R-93-003. April 1993, 4-
19.
31 The assumed CH 4 producing capacity of industrial landfill waste as a percentage of the CH 4 producing capacity of
the MSW nationally is 7 percent. This report assumes Nevada's producing capacity is 10.22 percent.
32 Note that the 100 year GWP of CH 4 is 25 times greater than that of CO2.
30View entire presentation