Waste-to-energy pathways for fresh and legacy waste management: A case study in India

• LFGR and RDF gasification combined significantly outperform the existing system • RDF gasification scenario recovers 2.2 times more net energy than RDF incineration. • 1 tonne CO2 reduction cost for LFGR is 20 USD, and for gasification case is 32 USD. • Net electricity output has a significant impact on the CC impact category. Rapid urbanization and population growth in developing countries like India have led to the dual challenge of managing the fresh municipal solid waste (MSW) and accumulated legacy waste in unregulated landfills. Despite the environmental significance of legacy waste, it is often overlooked in existing life cycle assessment (LCA) studies. This results in a critical gap in integrated LCA approaches that consider both waste streams within a single system boundary. This study addresses this gap by conducting an integrated attributional LCA, using the case study of Ghazipur landfill, Delhi, India. It covers processes from waste collection to energy recovery, using a functional unit of 1 tonne of MSW. LCA is performed using GaBi software and the Environmental Footprint 3. Four scenarios are analyzed: landfill without gas recovery (LF), landfill with gas recovery (LFGR) for fresh waste, refuse-derived fuel (RDF) incineration, and RDF gasification for legacy waste. LFGR shows an energy recovery of 73.04 kWh/tonne of MSW, significantly reducing the environmental impacts compared to LF. For legacy waste, RDF gasification outperforms incineration, showing an energy recovery of 306.1 kWh/tonne of MSW. The reduction cost of 1 tonne of CO 2 is 20 USD for LFGR and 32 USD for the RDF gasification. Sensitivity analysis highlights that the net electricity output predominantly affects the climate change category. This study highlights the potential of WtE for biomining and landfill reclamation, supporting circular economy transitions. The integrated LCA framework is replicable across developing nations with similar landfills, aligning with SDGs 7, 11, and 13.