Progress of international program on hydrogen production with the copper-chlorine cycle

This paper highlights and discusses the recent advances in thermochemical hydrogen production with the copper-chlorine (Cu-Cl) cycle. Extended operation of HCl/CuCl electrolysis is achieved, and its performance assessment is conducted. Advances in the development of improved electrodes are presented for various electrode materials. Experimental studies for a 300 cm² electrolytic cell show a stable current density and production at 98% of the theoretical hydrogen production rate. Long term testing of the electrolyzer for over 1600 h also shows a stable cell voltage. Different systems to address integration challenges are also examined for the integration of electrolysis/hydrolysis and thermolysis/electrolysis processes. New results from experiments for CuCl-HCl-H₂O and CuCl₂-HCl-H₂O ternary systems are presented along with solubility data for CuCl in HCl-H ₂O mixtures between 298 and 363 K. A parametric study of multi-generation energy systems incorporating the Cu-Cl cycle is presented with an overall energy efficiency as high as 57% and exergy efficiency of hydrogen production up to 90%.