A novel clean hydrogen production system combining cascading solar spectral radiation and copper-chlorine cycle: Modeling and analysis

In this work, a novel integrated hydrogen production system was proposed. A detailed analysis of the efficiency limit, energy requirement, and parametric impact was theoretically performed. The system combined cascading solar spectral radiation with a copper-chlorine thermochemical cycle, which effectively converted different grades of solar energy to clean hydrogen. The process of a four-step copper-chlorine cycle was simulated to obtain the energy demands using Aspen Plus software. A model for cascading utilization of solar spectral radiation was developed to select the optimal segmented wavelengths and investigate the effects of parameters on the system efficiency. The system designs integrated with other solar cells were also optimized using this model. Among the parameters, the segmented wavelengths were the key parameters that determined the amount of solar energy converted to heat and electricity. The theoretical calculations and simulations were used to determine the performance of this new hydrogen production system. Efficiency analysis demonstrated that the proposed system achieved an ideal efficiency of 68.20%, exceeding the theoretical limit of the single-junction photovoltaic-electrolysis water system. The efficiency of the actual design was 43.44%, higher than the systems without a spectrum splitting module. This study provides an efficient method for realizing high efficiency and high-grade solar energy cascading utilization for producing clean hydrogen energy. •A hydrogen production system using solar radiation and a Cu–Cl cycle is proposed.•The thermodynamic model for cascading utilization of solar spectrum is developed.•Cascading solar-driven Cu–Cl cycle is simulated using Aspen Plus.•The ideal system achieves an efficiency limit of 68.20%, showing great potential.•The actual energy efficiency is 43.44%, with a hydrogen production rate of 4.5 g/s.