Enhancing biomass CHP sustainability through two-stage waste heat recovery: An exergy, exergoeconomic, and life cycle assessment approach

• Novel two-stage waste heat recovery boosts biomass CHP exergy efficiency by 25%. • Reheat ORC with cooling recovery enhances utilization of high- and low-grade heat. • Exergy, exergoeconomic and LCA analyses link efficiency, cost and enviromental impact. • System cuts CO 2 and environmental damage by over 20% versus baseline. • Demonstrates a viable pathway for sustainable decentralized bioenergy systems. The global pursuit of sustainable and low-carbon energy solutions necessitates innovative strategies to enhance the efficiency and environmental performance of biomass-based combined heat and power (CHP) systems. In this study, an advanced biomass gasification CHP concept is introduced, incorporating a two-stage thermal recovery strategy designed to exploit high- and low-grade heat sources through complementary thermodynamic processes, thereby extending overall system efficiency and sustainability. A comprehensive 4E framework, encompassing energy, exergy, exergoeconomic, and environmental analyses through life cycle assessment (LCA), is applied to evaluate the proposed system and benchmark its performance against a conventional biomass CHP reference. The results reveal that the new configuration achieves energy and exergy efficiencies of 80.5% and 24.9%, respectively, compared to overall efficiencies of 62% and 22% in the reference system, while delivering 100 kW of net power and 268 kW of useful heat. Exergoeconomic analysis identifies the engine and gasifier subsystems as the most cost-intensive components, responsible for over 70% of total exergy destruction costs. Despite a slight increase in investment cost (from $5.6/h to $6.65/h), the proposed system provides more cost-effective energy recovery with a 6.6% reduction in CO 2 emissions. Furthermore, comparative LCA results confirm notable sustainability gains, including reductions of 20.6% in global warming potential and 20.3% in human health impacts relative to the baseline system. Overall, the proposed two-stage thermal recovery concept within a 4E–LCA framework demonstrates a technically efficient, economically viable, and environmentally sustainable pathway for advancing decentralized biomass-based energy conversion systems.