Techno-economic evaluation of solar-driven ceria thermochemical water-splitting for hydrogen production in a fluidized bed reactor

Thermochemical water splitting (TCWS) is an attractive and promising approach for hydrogen fuel production to replace fossil fuels and address climate change. The novel approach used in this study is the indirect irradiation of the ceria particle with solar-heated nitrogen in a fluidized bed reactor which improved the ceria thermo-reduction and increased hydrogen yield. The TCWS plant featured additional units for oxygen co-production, and excess heat recovery to generate electricity and reduce the saleable hydrogen price. Two fluidized bed reactors for ceria thermo-reduction and oxidation using steam were modelled in Aspen Plus for hydrogen production at a 70% capacity factor. A photovoltaic (PV)-battery module in addition to the solar parabolic dish collector (PDC) was then used to deliver operation-round electricity supply and drive mechanical and control systems, reducing overall plant energy cost. Three minimum selling prices of hydrogen were considered based on the achievable products of the TCWS plant: (i) pricing based on no co-products, (ii) pricing including oxygen revenue, and (iii) pricing including oxygen and electricity revenue. The TCWS plant achieved a minimum selling price (MSP) of 3.92 USD/kg H2 (including oxygen and electricity revenue) at a 10% discount rate which is the lowest for solar-driven TCWS hydrogen compared with other similar studies. Sensitivity analyses showed that discount rate, steam Rankine cycle, power block, cost of ceria and hydrogen storage, and price of oxygen, respectively, had the highest impact on the MSP of the TCWS hydrogen plant. The switch value analysis (SVA) was used to determine the potential of achieving the global target hydrogen price of 2 USD/kg based on a single parameter assessment. The TCWS plant proposed in this work provides a promising approach toward achieving future hydrogen prices below 2 USD/kg when a lower discount rate of 5% is utilised. It was established that the choice and size of concentrated solar power (CSP) technology integration, co-generation, and heat recovery are critical to the system efficiency and economic viability of a solar-driven TCWS hydrogen production. This work demonstrated the use of ceria as a metal oxide feed suitable for solar TCWS hydrogen production with a promising economic potential for a global target price of less than 2 USD/kg H2 based on the choice of process-CSP configuration.