Concentrated solar thermal integrated with a novel dual-rock bed thermal energy storage for solar industrial process heat: energy and economic analysis

Parabolic trough collectors are a mature and reliable technology for integrating solar energy into industrial heat supply. The proposed system combines an air-fed parabolic trough collectors solar field with a thermal energy storage composed of two parallel rock beds. This configuration is an innovative solution that ensures continuity in both solar energy collection and thermal load delivery. A dedicated control strategy is designed to efficiently manage the charging and discharging phases of the two tanks. Due to the variability of solar energy, a long-term dynamic analysis was performed to accurately assess system performance. The plant was evaluated through a dynamic energy analysis and an economic assessment based on a case study of an air-based pasta drying plant with a nominal thermal load of 120 kWth. A parametric study was carried out by varying the solar field size and layout, as well as the storage capacity, in order to determine their influence on energy performance and the Levelized Cost of Heat (LCOH). The results indicate a maximum solar fraction of 86.71%, while the lowest LCOH obtained is 5.0 c€/kWh, corresponding to an energy saving of 48.6%. A sensitivity analysis complemented the outcomes. The study demonstrates the strong energy and economic potential of this innovative solar thermal system.