Use of Models and Facility-Level Data in Greenhouse Gas Inventories

Use of Models and Facility-Level Data in Greenhouse Gas Inventories
value of oxidation factor for landfill was fixed at 0.15 following Chomsurin (1997). However, OX of dumpsite had been
evaluated by error function analysis.
RESULTS
Methane emissions from field investigation
In this experiment, concerning the fluctuation of weather in tropical country during year round, we measured methane
emissions from 9 disposal sites in Thailand during wet and dry seasons. There are three seasons in Thailand according
to weather data and amount of rainfall namely, rainy, winter and summer seasons. Weather data from Thai
Meteorological Department showed that the average atmospheric temperature during emission measurement in the
rainy, winter and summer seasons were 28.5, 26.5 and 29.2 o C, respectively. However, the monthly precipitation rate
had significant differences that were 258.4, 30.5 and 134.6 mm./month in the rainy, winter and summer seasons,
respectively. The surface methane emission results are summarized in Table 2. These results indicated that high spatial
heterogeneity of methane emission (high standard deviation) can be found in all study sites especially in wet season.
The phasing of waste tipping was the main reason of the high spatial heterogeneity at all disposal sites that waste was
degraded under different degradation stage. In this study, most of high methane emissions were found at the younger
phase compared to older phase that gave low CH 4 emissions. From Figure 2, It can be seen that manage landfill showed
high methane emission than unmanaged landfill for the whole season. In addition, methane emissions of manage landfill
during the wet season (rainy season) were about 5 - 6 times higher than dry season (winter and summer seasons)
whereas it was only 2 - 5 times in unmanaged landfills. Although methane emission during winter and summer were low,
theirs values were in close proximity in the managed landfill and were two times different in the unmanaged landfill.
Moisture content in the waste body might be the most important parameter in the waste degradation. In the wet season,
moisture content in the waste body will be increased by intrusion of rain passing through daily cover. The additional
moisture stimulates microbial activity by providing better contact between insoluble substrates, soluble nutrients and
microorganisms. These phenomena enhance decomposition and generate more LFG (Barlaz et al., 1990).
Figure 2 Emission of methane per ton of waste in place per day from the different landfill sites during rainy, winter and
summer season
As anticipated, the average spatial methane emissions from unmanaged landfill were substantially lower than from
managed landfills in all seasons. Moreover, the average spatial methane emissions in shallow landfill were lower than
deep landfills. This may have resulted from the intrusion of air into the landfill which might decrease anaerobic waste
degradation. The waste is stabilized rapidly through aerobic condition that has an additional benefit of reducing landfill
emissions of methane (Peck et al., 2007). The waste degradation phenomenon in shallow landfill seems as if it was
IPCC Expert Meeting Report 58 TFI