Enhancing energy recovery from waste through torrefaction: A study on municipal solid waste (MSW) fractions under N₂ and CO₂ atmospheres

This study investigates the impact of torrefaction on municipal solid waste (MSW) fractions, focusing on energy recovery, calorific value enhancement, mass yield reduction, and energy densification under both nitrogen (N 2 ) and carbon dioxide (CO 2 ) atmospheres. As waste production increases globally, driven by population growth and industrialization, there is growing interest in waste‐to‐energy conversions to address both energy demand and waste management concerns. Torrefaction, a thermochemical pretreatment, enhances the properties of solid waste to make them more suitable for energy recovery processes like pyrolysis and gasification. This study demonstrated that torrefaction effectively addresses the low energy content of MSW, achieving an energy densification ratio up to 1.73. The process showed high energy efficiency, with energy recovery ranging from 69.3% to 99.15%, while different waste fractions exhibited varied behaviours during torrefaction. Lemon peels exhibited the highest energy densification while paper cups achieved the highest energy recovery but minimal energy densification. Wood waste fractions, such as white spruce sawdust and forest residues, demonstrated balanced performance with high energy recovery and moderate energy densification, making them ideal candidates for prioritizing high energy recovery applications. The results show that the use of CO 2 , representing flue gas, enhances volatile release and improves energy densification in some fractions, particularly forest residues, compared to N 2 , while also promoting better carbon retention at higher temperatures. Overall, this study highlights the importance of waste stream selection, torrefaction atmosphere, and temperature optimization to improve the efficiency of MSW torrefaction, offering insights for the use of flue gas torrefaction in waste‐to‐energy processes.