Industrial Rock Packed-Bed Heat Storage System:

The first industrial-scale packed-bed configuration for a Thermal Energy Storage (TES) using rocks, offering a thermal capacity of 100 MWhth, has been constructed for a Concentrated Solar Power (CSP) facility in Ait Baha, Morocco. It employs environmentally friendly materials, using natural pebbles as the energy storage material and ambient air as the heat exchange fluid. The storage unit features an innovative design characterized by a truncated-cone form, is embedded in the ground, and operates at high temperatures ranging from 293K to 843K. To assess the thermal performance and behavior of the system, a verified Computational Fluid Dynamics (CFD) method is employed over thirty days of operation under real-world daily conditions. The results of the cyclic behavior show that the impact of thermal cycles is most pronounced in the initial cycles, while thermal stratification during both the energy storage and release phases is significantly enhanced through repeated operation. Furthermore, the system's performance improves over the thermal cycles, achieving an efficiency of 80% by the 30th cycle.