Experimental analysis of a power-to-heat storage with high-temperature phase change materials to increase flexibility and sector coupling

To boost the flexibility, sector coupling and manageability of renewable energy systems, a unique power-to-heat storage (electric charging, thermal discharging) is proposed. The hybrid thermal energy storage system, including phase change materials, is built using flat pillow-plates and heating rods. Experimental testing is conducted to assess the prototype's electrical and thermal performance. In addition, a parametric study involving several charging and discharging control strategies is proposed in this context.The suggested hybrid thermal storage system provides a total storage capacity of 4.87 kWh using nitrate salts as phase-change material (eutectic mixture of KNO3 and NaNO3). The charging efficiency ranges from 65 to 90%, depending on the charging/discharging strategy, and the discharging period can be shortened by more than 1 h. Additionally, active management of the heating rod temperature reduces the charging period by half, making the storage system highly flexible. This demonstrates the ability of this system to aid in modularity and flexibility for effective energy management in the context of renewable energy and industry thanks to an increased storage capacity.