As municipal solid waste (MSW) in landfills can reach temperatures greater than 50°C that may be sustained for several decades due to methanogenic bacteria activity, the generated heat is an alternative energy source that can be exploited for direct heating of nearby infrastructure or for augmenting industrial processes. However, in-situ measurements of MSW thermal properties are needed to properly design heat extraction systems for landfills. In this study, the spatial and temporal evolution of the waste temperatures in a new MSW landfill cell in Santee, California were monitored over 13 months. After the temperatures reached stable values, a 17-day heat extraction thermal response test was performed on serpentine geothermal heat exchangers that were installed at three elevations in the cell during waste placement. As the serpentine segments were separated from each other to minimize thermal interference during the heat extraction test, the pipes were assumed to represent line heat sinks. The values of effective thermal conductivity estimated from infinite line source analyses ranged from 0.86 to 1.32 W/m°C , which are consistent with values on the higher range of those from laboratory tests on MSW.

In this study, a two-dimensional finite difference model was used to simulate the heat transfer occurred during a 17-day heat extraction test performed in an MSW landfill cell in Santee, California. The heat extraction was performed using serpentine horizontal heat exchangers installed 6 m above the base liner of the cell, and it started after the waste reached a stable temperature value of 52 °C. The model was developed based on the differential heat conduction equation and an inverse analysis was performed to estimate the thermal diffusivity of the waste. The values of in-situ thermal diffusivity obtained ranged from 7.85  10 -7 m 2 /s to 1.05  10 -6 m 2 /s and are consistent with the higher range of values presented in the literature for MSW.

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