Investigating the effects of ZnO dopant on the thermodynamic and kinetic properties of CaCO3/CaO TCES system

CaCO 3 /CaO based thermochemical energy storage system has a promising potential for the concentrated solar power plants. However, the low reactivity and sintering of CaCO 3 /CaO restricts the energy storage/release performance of this system. In this work, we report ZnO as a new doping material for the CaCO 3 /CaO TCES system. We tested different loadings of ZnO and determined an optimal loading for the best performance. The reaction kinetics of both the doped as well as the undoped system in the decarbonation step is presented in detail. Furthermore, the energy storage capacity and the cyclic stability over first 100 cycles is reported. It is found that the ZnO-doped CaCO 3 can absorb 1478.8 J/g energy at the optimal loading. The cyclic conversion of the ZnO-doped system stabilizes after 20 cycles, which is an improvement from the undoped system that shows a slow but steady decline even after 100 cycles. ZnO seems to be a viable doping material, which considering its low cost and availability can lead to an improved thermochemical energy storage system.