Experimental validation of a hybrid power-to-heat storage based on high temperature phase change materials to enhance sector coupling and flexibility

An innovative power-to-heat storage (electric charging, thermal discharging) is proposed to increase the flexibility, sector coupling and manageability of renewable generation systems. The hybrid thermal energy storage (TES) system integrating phase change materials (PCM) is designed based on flat pillow plates in combination with heating rods. The prototype is validated by means of experimental testing to characterize its electrical and thermal. In this sense, a parametric analysis is proposed involving different charging and discharging control strategies. The proposed hybrid-TES provides a total storage capacity of 4.87 kWh integrating nitrate salts as PCM (eutectic mixture of KNO3 and NaNO3). Depending on the charging/discharging strategy, the charging efficiency is 65-90% and the discharging period could be reduced by more than 1h. Active control of the heating rod temperature reduces the charging period by half, enabling a high flexibility of the storage system. This reveals the PCM-TES potential to contribute in decision-making for an optimal energy management in the renewable energy and industry context.