Abstract
Methane is a major component of landfill gas (LFG) generated during the anaerobic degradation of municipal solid waste, and its uncontrolled emissions contribute substantially to global warming. However, methane holds recoverable energy potential, providing an opportunity to mitigate greenhouse gas emissions. The present study investigates potential methane emissions and techno-economic feasibility from three open dumpsites in Chennai, Coimbatore, and Madurai. Waste disposal data from 2000 to 2020 were collected, and future dumping was projected up to 2050, with a closure year of 2050. Methane emissions were assessed using intergovernmental panel on climate change (IPCC) methodology, Solid Waste Emission Estimation Tool (SWEET) 4.03, and Landfill Gas Emission Model (LandGEM) 3.03, with both default and site-specific input parameters. The model results reveal a peak in methane emissions in 2050, with IPCC methodology magnitudes of 158.10, 34.83, and 14.62 Gg year
−1
for Chennai, Coimbatore, and Madurai, respectively. LandGEM predicted 122.68, 18.39, and 5.96 Gg year
−1
for the three dumpsites, respectively. SWEET predicted substantially higher emissions of 3608.10, 789.56, and 363.53 Gg year
−1
by incorporating degradable organic carbon decomposition and dynamic, waste-fraction-specific decay kinetics under open-disposal conditions. The techno-economic feasibility analysis was performed using the LFGcost-Web tool, considering direct-use and turbine-based technologies. The analysis indicated negative net present values ranging from −6.46 to −22.67 million USD and an internal rate of return between −12% and −49%, demonstrating limited financial viability under the prevailing Indian market conditions. Among the evaluated options, direct-use achieved the highest greenhouse gas mitigation potential and methane utilization, whereas combined heat and power systems provided higher overall energy-recovery efficiency, where simultaneous electricity and heat demand exists.