Design and thermodynamic assessment of a sustainable waste to energy system for multiple useful outputs

This study includes the development and thermodynamic performance assessment of a new sustainable multigeneration system, with the Woodward Avenue Wastewater Treatment Plant in Hamilton, Ontario, Canada selected as a potential implementation site. The integrated configuration covers sludge incineration, dark fermentation (DF), hydrochar production via hydrothermal carbonization (HTC), organic Rankine cycle (ORC), multi-effect desalination (MED), and a wind farm subsystem to simultaneously produce hydrogen, hydrochar, freshwater, and electricity from wastewater sludge and renewable energy sources. The proposed system achieved an overall energy efficiency of 48% and an exergy efficiency of 42%, demonstrating strong thermodynamic balance and effective heat recovery. The present system is potentially designed to produce approximately 13,950 kg of hydrogen, 1490 tonnes of hydrochar, 35,500 m3 of freshwater, and 160 MWh of electricity annually. The results confirm that the integrated system provides an efficient and sustainable approach for waste-to-energy conversion and resource recovery, enabling simultaneous production of clean energy and valuable by-products. An exergoeconomic analysis further highlights the dominant cost drivers and confirms the economic feasibility of the proposed integrated system. The proposed configuration represents a feasible pathway toward low-carbon, circular, and energy-positive wastewater treatment infrastructure.