(137f) Comparison of Sulphur–Iodine, Copper–Chloride and Hybrid-Sulphur Thermochemical Cycles for Hydrogen Production

The rapid increase in worldwide energy demand, caused by the rise in global population and living standards, has led to higher greenhouse gas emissions and diminishing fossil fuel reserves. To address these challenges, there has been growing R&D for new alternative energy solutions to address global energy requirements and environmental problems. Nuclear energy is one of the more promising low-carbon sources for large scale energy production. Renewable energy sources have been limited due to their cost, reliability and availability.

Hydrogen is one of the promising, clean and effective energy carriers. Hydrogen can be produced using either nuclear or renewable energy sources. Many past studies have focused on developing efficient and economic pathways for hydrogen production. Thermochemical cycles are one of the most promising methods for large-scale hydrogen production, and these cycles are usually classified according to the chemicals used in the processes.

The sulphur-iodine, copper-chloride and hybrid-sulphur water splitting cycles are promising methods of thermochemical hydrogen production. The sulphur?iodine cycle involves three thermochemical steps. The copper?chlorine cycle involves five steps, of which four are thermally driven chemical reactions, and one is an electrochemical reaction. The hybrid-sulphur cycle involves two steps, of which one is a thermochemical reaction and the other is an electrochemical reaction. This paper compares these three cycles from the perspectives of energy, exergy, efficiency and cost. The major engineering advantages and disadvantages of these cycle variations are analyzed and discussed.

Keywords: Hydrogen, energy, exergy, sulphur-iodine, copper-chloride, hybrid-sulphur, water splitting cycles, thermochemical cycles.