Renewable Energy-Driven Torrefaction of Municipal Solid Waste for Sustainable Solid Fuel Production: A Gate-to-Gate Life Cycle and Net Energy Assessment

This study presents a gate-to-gate life cycle assessment (LCA) comparing the environmental impact of three torrefied municipal solid waste (MSW) energy sources (S1) solar photovoltaic (PV), (S2) grid electricity from India and (S3) biomass combustion. Experiments performed in a laboratory setting produced a yield of transitory MSW torrefaction of 28–32% at an input fuel energy of 2 kWh/kg at 200–300 °C for 30–60 min. The ReCiPe 2016 midpoints [Global Warming Potential (GWP); Human Toxicity Potential (HTP); Acidification Potential (AP); Particulate Matter Formation Potential (PMFP)] showed PV produced the least number of emissions (GWP = 0.0426 kg CO2 equivalent; HTP = 0.00988 kg 1,4-DB equivalent), while grid power produced the greatest number of emissions (GWP = 2.2 kg CO2 equivalent). Biomass produced intermediate results (GWP = 1.546 kg CO2 equivalent). All sources had an average positive net energy ratio of approximately 2.78. The results indicate that integrating renewable energy sources significantly increases the environmental and social benefits of the torrefaction process. Additionally, the study provides a MS Excel-Based LCA framework to use when data are limited.