Clay/phosphate-based ceramic materials for high temperature thermal energy storage – Part II: Validation of high temperature storage performance at pilot scale

The performances of a pilot scale packed bed thermal energy storage system filled with 162 kg of developed phosphate-based ceramic materials (cylinders of 1.5 cm × 4 cm) was experimentally investigated under different operating conditions of inlet air temperature for the charge (334 +/- 21 °C, 531 +/- 23 °C and 760 +/- 15 °C), air flowrate for charging and discharging (26.5 to 74 kg/h), as well as under consecutive cycles. The packed bed performed well at different temperature and charge / discharge flowrate. The cylindrical shape of the produced clay/phosphate-based ceramic combined with the horizontal implementation of the storage tank did not provoke a significant preferential path for the air inside the storage medium and did not create a significant thermal de-stratification during the charging and discharging phases. Furthermore, under consecutive cycles, the TES system could be quickly stabilized demonstrating the robustness and flexibility of the developed TES system, which can cover a wide range of application cases. The production of the developed ceramics is mastered by ceramic industries allowing the availability at industrial scale worldwide with competitive cost and carbon footprint. This work opens new prospects for using phosphates-based ceramics as alternative promising media to build new generation of flexible and reliable high temperature TES system for industrial assets decarbonation, grid services as well as renewable energies high penetration into the grid.