Al/Mn Co‐Doped Calcium‐Based Materials for High Performance Direct Solar‐Driven Calcium Looping Thermochemical Energy Storage

ABSTRACT CaO/CaCO 3 thermochemical energy storage, also known as calcium looping (CaL), has promising applications in high‐temperature concentrating solar power (CSP) plants due to their wide range of material source, low price, high storage density, and suitable reaction temperature. However, calcium‐based materials are gradually deactivated due to sintering and agglomeration, which reduce the cyclic stability of the materials. In this paper, calcium composites containing Al and Mn elements were prepared by a template method. The addition of Al and Mn elements to the materials resulted in a significant increase in the thermal storage capacity and light absorption property. The optimum ratio of Ca:Al:Mn is 100:2.5:2. The initial effective conversion rate and energy storage density of the calcium composite were 0.91 and 2893 kJ/kg, respectively, with only a 6% decrease after 10 cycles. Both the conversion and light absorption properties of the materials contribute to the system power generation efficiency of CSP‐CaL integration system. By increasing the CaCO 3 conversion rate from 0.5 to 0.87, the power generation efficiency is improved from 25.79% to 34.03%. At the same time, the total exergy loss of the system is decreased by 8.98%. Under the CaCO 3 conversion rate of 0.5, increasing the solar energy input from 100 to 110 MW improves the power generation efficiency from 25.79% to 43.27%. This study sheds light on improving the energy efficiency of CSP‐CaL system through material optimization.