A Hybrid Energy Storage System Based on Metal Hydrides for Solar Thermal Power and Energy Systems

Thermal storage in an important operational aspect of a solar thermal system which enables it to deliver power or energy when there is no sunlight available. Current thermal storage systems in solar thermal systems work based on transferring the generated heat from sunlight to a thermal mass material in an insulated reservoir and then withdraw it during dark hours. Some common thermal mass materials are stone, concrete, water, pressurized steam, phase changing materials, and molten salts. In the current paper, a hybrid thermal energy storage system which is based on two metal hydrides is proposed for a solar thermal system. The two hydrides which are considered for this system are magnesium hydride and lanthanum nickel. Although metal hydride Energy Storage Systems (ESS) suffer from slow response time which restricts them as a practical option for frequency regulation, off peak shaving and power supply stabilization; they can still demonstrate significant flexibility and good energy capacity. These specifications make them good candidates for thermal energy storage which are applicable to any capacity of a solar thermal system just by changing the size of the ESS unit.