Life cycle assessment of hydrogen production via thermochemical water splitting using multi-step Cu–Cl cycles

A comparative environmental impact study of the three-, four- and five-step copper–chlorine (Cu–Cl) thermochemical water splitting cycles is undertaken through life cycle assessment (LCA). This analytical tool is used to identify and quantify environmentally critical phases during the life cycle of a system or a product and/or to evaluate and decrease the overall environmental impact of the system or product. The LCA results for the hydrogen production processes indicate that the four-step Cu–Cl cycle has lower environmental impacts than the three- and five-step Cu–Cl cycles due to its lower thermal energy requirement. The global warming, acidification and eutrophication potentials of the system using the four-step Cu–Cl cycle are 0.56 kg CO2-eq, 0.00284 kg SO2-eq and 0.000232 kg Phosphate-eq, respectively.