Thermo-economic characteristics and cost-influencing mechanism analysis of an advanced nuclear-powered zero-carbon hydrogen-electricity co-production system with sulfur-iodine process and combined cycle

The fourth-generation Very High Temperature Reactor (VHTR) holds great promise as a reactor type for large-scale clean hydrogen (H₂) production in conjunction with the Sulfur-Iodine (SI) thermochemical process. However, limited research exists on the design and economic analysis of coupled VHTR and SI process nuclear hydrogen production systems, particularly when the combined cycle is incorporated as a power cycle within the system. To address this issue, we have developed and examined an advanced VHTR-driven hydrogen-electricity co-production system that adopts the SI process and combined cycle. The system has been modeled from both thermodynamic and economic perspectives, and its thermo-economic performance has been assessed under various operating conditions. Several parametric studies have been conducted to elucidate factors influencing the unit H₂ production cost. The simulation results demonstrate that the thermal efficiency of the proposed SI process is in the range of approximately 27.95%–35.28%, and under the baseline operating condition, the whole system can concurrently produce hydrogen at a rate of about 290 mol/s while generating around 103 MW of net electric power, with thermal efficiency, exergy efficiency, and unit H₂ production cost of about 37%, 36%, and 4.32 $/kg, respectively. The unit H₂ production cost of the proposed system is predicted to range between approximately $1.5/kg and $7/kg. Finally, it has been determined that increasing the reactor thermal power, extending the system lifetime, improving the cost capacity factor and unit electricity price, as well as decreasing the mass flow ratio and interest rate, all contribute to a reduction in the unit H₂ production cost.