A novel cascade resorption system for high temperature thermochemical energy storage and large temperature lift energy upgradation

Abstract

The discrepancy between energy supply and demand can be overcome by sorption based thermochemical energy storage system. Thermochemical energy storage system based on metal hydrides is an attractive option due to cyclic stability and high energy storage density. In the present study a novel cascade resorption system is proposed and analyzed for high temperature energy storage. The cascade resorption system uses Mg-50 wt% LaNi5 for energy storage due to its high reaction enthalpy and hydrogen absorption capacity whereas LaNi5 and LaNi4.7Al0.3 are used for hydrogen storage. The temperature at which energy is recovered is increased by two stage cascading desorption method. Therefore, a large magnitude of energy upgradation is possible. An energy upgradation of 52 °C is obtained using the cascade resorption system when the energy source and regeneration temperatures are at 300 and 80 °C, respectively. Thermodynamic analysis shows that the COP and energy storage density of 0.419 and 141.323 kJ/kg, respectively are obtained. In the end, cascade resorption system is compared with the simple resorption system and discussed the relative merits of cascade system. The energy upgradation of 18 and 23 °C is obtained using two simple resorption systems.