Thermochemical Energy Storage Using a Strontium Oxide/Strontium Carbonate Carbonation Cycle

Concentrated solar power (CSP) is one promising method of converting clean solar thermal energy into electricity which avoids the use of fossil fuels.  Thermal energy storage (TES) in conjunction with CSP can increase the utilization of solar energy by enabling plant operators to generate electricity beyond normal on-sun hours. Thermochemical energy storage (TCES) is an emerging type of TES system based on a reversible reaction that offers higher energy density than latent or sensible energy storage. Thermochemical energy storage of on-sun thermal energy is achieved when a reactive system absorbs thermal energy and proceeds with a reversible chemical reaction. In a time of off-sun power demand, the reverse reaction is then initiated and energy is released, thus recovering thermal energy for use in a power cycle.  One such reactive system is the reversible carbonation/decomposition of SrO/SrCO₃, which occurs ca. 1200°C.  Such high quality heat is suitable for high efficiency, combined cycle power generation, which has the potential to translate into more competitive solar electricity prices.  The current status of the SrO/SrCO₃ technology will be presented, including areas for improvement in achieving high conversion and fast kinetics.