Development and factory verification of the high-energy density thermochemical storage system

This work targets the practical use of thermal energy storage technologies to effectively utilize unused heat. As thermal energy storage material we focused on the CaO/Ca(OH)2 chemical reaction, which has high energy densities and is practical from the viewpoints of material abundance and environmental influence. We developed a thermal energy storage molded plate that solves the trade-off problem of how to increase the thermal output while suppressing the output power decrease resulting from repeated use. We also developed a thermochemical storage system equipped with a reactor containing reactive substances that charge and discharge heat. The thermal energy storage molded plate is installed in the reactor. The energy efficiency estimated using a proof test performed in a mass-production-sized plant is approximately 70%, which indicates the effectiveness in the current system. In addition, the plate is proved to release heat at a temperature of 550°C, demonstrating the potential to further increase the energy efficiency. The plate can also function as a heat pump, which is expected to be utilized to increase the temperature to a level that cannot be reached using sensible heat storage mechanisms. In this work, we propose our thermochemical storage system as a future thermal energy storage technology that can be applied in fields including solar thermal power generation.