Integration of third-generation concentrated solar power and solid oxide electrolysis for dispatchable solar hydrogen production: Multi-variable optimization and techno-economic assessment

This study presents a third-generation (Gen3) concentrated solar power (CSP) system integrated with solid oxide electrolysis cells (SOECs) for dispatchable hydrogen production. The configuration combines a liquid sodium central receiver, ternary chloride molten salt (MgCl 2 -KCl-NaCl) thermal energy storage, a recompression supercritical CO 2 Brayton cycle operating at 700°C, and an SOEC at 800°C. System performance is evaluated using an integrated thermodynamic, exergy, exergoeconomic, and techno-economic framework under Almería, Spain conditions (direct normal irradiance, DNI, 2240 kWh/m 2 /yr). The baseline system achieves a 69.5% capacity factor, substantially exceeding typical second-generation CSP plants, with overall energy and exergy efficiencies of 24.2% and 25.7%, respectively. Component-level exergoeconomic analysis identifies the SOEC stack and receiver assembly as dominant cost drivers, confirming that capital cost reduction is the primary improvement pathway. Multi-variable genetic algorithm optimization identifies a global optimum achieving a levelized cost of hydrogen (LCOH 2 ) of 3.84 $/kg at a 70.9% capacity factor. Techno-economic assessment shows that electricity cost is the dominant economic driver: reducing it from 55.66 to 20 $/MWh lowers LCOH 2 by approximately 1.19 $/kg, more than three times the benefit achievable through complete SOEC maturation by 2050. Net present value (NPV) analysis confirms project viability without policy support (86.2 M$ NPV, 19-year payback), with carbon pricing providing superior long-term value over production subsidies. The results highlight the strong potential of Gen3 CSP–SOEC systems for dispatchable green hydrogen production in moderate-DNI regions, leveraging mature sodium receiver technology.