Efficient Utilization of Industrial Waste Heat for Hydrogen Production via Cu-Cl Thermochemical Water Splitting Cycle

Abstract

Hydrogen production through water splitting involves separating hydrogen and oxygen using different technologies. The copper-chloride (Cu-Cl) cyclic reaction is a promising method of hydrogen production due to its low operating temperature, which allows it to use low-grade waste heat from industries, leading to reduced heat discharge to the environment. The process forms a closed loop, with all intermediate chemicals being recycled. All of the chemical and electrochemical reactions can be carried out at temperatures that do not exceed about 530 °C. The heat requirement of this process can be satisfied by an intermediate temperature. This study aims to assess the energy efficiency of an integrated system comprising a chemical heat pump as a heat recovery unit and copper-chloride thermochemical cycle water splitting for hydrogen generation. The simulation is conducted using Aspen Plus software to analyze the energy and mass balance of each stream in the process. The results indicate that the Cu-Cl cycle alone has an energy efficiency of 41.14 % and an internal heat recovery ratio (IHHR) of 72 %. Integrating the Cu-Cl cycle with two chemical heat pump hierarchies could enhance the overall process efficiency to 48.14 %.