Mayenite-supported CaO for thermochemical storage applications: Analysis of dynamic behavior under charging/discharging cycles

The possibility of storing solar thermal energy to decouple electricity production from the availability of the solar resource is a key factor in development of concentrating solar power (CSP) technologies. In this context, a challenging perspective is the storage of solar energy on a seasonal basis through thermochemical storage (TCS) systems, as well as the use of excess summer solar energy for stabilizing the annual electricity production, thus increasing the capacity factor of the CSP plant. In this paper, we report the experimental characterization of a material initially developed within the context of CO2 capture technologies, namely calcium oxide supported on mayenite, which in previous investigations shown good sorption capacity and substantial cycling stability. The objective of this new experimental campaign is to test the performance of this material when adopted for thermochemical storage purposes. The tests confirmed that the material, synthesized through a SolGel method, remains stable over long term cycling, with a carbonation conversion higher than 80%. Furthermore, no physical/chemical interaction of the mayenite support with CO2 was observed, confirming its inertia and suitability for TCS purposes.