Phase change material cascade storage for CSP: A performance evaluation

The integration of supercritical CO 2 (sCO 2 ) Brayton cycles in Concentrating Solar Power (CSP) plants offers a pathway to higher thermal efficiencies compared to conventional Rankine cycles. However, achieving high operational temperatures demands advanced Thermal Energy Storage (TES) solutions beyond the limits of traditional molten salt systems. This study evaluates a novel cascade phase change material (PCM) TES system, comparing it to a single PCM storage configuration under identical operating conditions to assess its feasibility for large-scale CSP applications. The results demonstrate that the cascade PCM TES system achieves an 282 % increase in energy storage capacity and enables more stable thermal management. A new two-dimensional model is developed to simulate the thermal behavior of PCM–metal wool composites in both single and cascade configurations under CSP operating conditions. The findings underscore the advantages of cascade PCM TES systems, particularly in maintaining solar salt as a viable heat transfer fluid while supporting next-generation sCO 2 power cycles. Additionally, the hybridization potential of this system allows direct integration with surplus renewable electricity, increasing dispatchability and grid flexibility. These advancements position cascade PCM storage as a promising solution for cost-effective, high-efficiency CSP deployment.