Energy recovery and landfill methane emission reduction from municipal solid waste: implications for climate mitigation in Nepal

Rapid urbanization and the associated escalation in municipal solid waste generation, especially across developing countries, have emphasized the necessity for a circular waste economy approach, within which sustainable waste-to-energy strategies play a critical role. This study presents an integrated analysis of methane generation potential renewable electricity potential, and hydrogen recovery from large-scale landfill systems, using the Banchare Danda Landfill Site (BDLS) in Nepal as a representative case study for low-income countries. Methane (CH 4 ) emissions were estimated using two worldwide models, Landfill Gas Emissions Model (LandGEM) and the First-Order Decay (FOD) methods, to ensure resilience and methodological validation. Six comprehensive scenarios were developed to capture a range of potential future trajectories based on predictive evaluation across multiple sectors. The LandGEM model predicted a peak CH 4 emission of 15.28 kilo-tonnes per year (kt yr⁻¹), whereas the IPCC model yielded 28.9 kt yr⁻¹ in 2052. The cumulative methane yield of 1.34 × 10 9 m 3 corresponds to a recoverable energy potential of 52.7 × 10 6 kWh yr⁻¹ and a hydrogen generation capacity of 16.0 × 10 6 m 3 yr⁻¹ under baseline conditions. Scenario analysis revealed that a 1.5% annual increase in per capita waste generation could raise energy recovery to 87.3 × 10 6 kWh yr⁻¹, while enhanced recycling (50%) could diminish CH 4 emissions by approximately 24%. Techno-economic assessment indicated a positive net present value of USD 0.64 million and a greenhouse gas mitigation potential of 2.32 million tonnes of CO 2 equivalent (MT CO 2 eq). These findings demonstrate the technical and environmental viability of landfill gas valorization to support low-carbon transitions in emerging economies.