Food waste gasification integrated with electrochemical reduction of carbon dioxide for advanced hydrogen production: Energy, techno-economic, and environmental analyses

Hydrogen production from waste resources offers a promising solution to support the transition toward a sustainable energy system. Meanwhile, CO₂ electrochemical reduction (CO₂ER) uses renewable electricity to produce CO, which can be utilized for fuel and chemical synthesis or hydrogen production. Although previous studies have explored CO₂ER integration with fossil-based reforming systems, its application to waste-derived syngas—particularly from food waste—remains unexplored within the context of waste-to-hydrogen systems. This study proposes an integrated process that captures CO₂ generated from food waste gasification and electrochemically reduces it to CO, aiming to enhance hydrogen production while improving carbon utilization. Additionally, the integration of oxy-fuel combustion using O₂ derived from CO₂ER enables efficient CO₂ capture and process heat recovery. Both the conventional and integrated processes were simulated and evaluated in terms of energy, economic, and environmental performance. The integrated process increases hydrogen output by approximately 1.8 times, raising energy efficiency to 61.60 %, despite the high power demand of CO₂ER. The levelized cost of hydrogen (LCOH) achieves $2.91/kg, which is 7.4 % lower than that of the base process. The process maintains high hydrogen productivity and energy efficiency across varying food waste compositions from different countries, further demonstrating economic feasibility. Sensitivity analysis reveals that the process exhibits relatively high price stability under fluctuating renewable electricity prices. However, LCOH is significantly influenced by CO₂ER stack performance, particularly cell voltage, single-pass conversion, and Faradaic efficiency, underscoring the necessity for stable and high-performance operation to ensure commercial viability. Environmentally, both processes achieve over 99 % CO₂ capture efficiency, reaffirming the potential of food waste as a sustainable hydrogen feedstock. In conclusion, the gasification-CO₂ER process demonstrates strong commercialization potential as an innovative bio-hydrogen production pathway, contingent on the availability of low-cost renewable electricity and continued advancements in CO₂ER technology.