Thermochemical Energy Storage of Concentrated Solar Power by Novel Y<sub>2</sub>O<sub>3</sub>-Doped CaO Pellets
Hailong Li, Yingjie Chen, Lijian Leng, Yingchao Hu
Abstract
Reliable energy storage technology is a prerequisite for the efficient utilization of solar energy, among which thermochemical energy storage based on calcium looping emerges as a promising candidate. In this work, antisintering Y2O3 was doped into CaO to prepare a novel composite for energy storage. Benefiting from the homodispersity of Y2O3 in active CaO, which was proved by both scanning electron microscopy and transmission electron microscopy analyses, the novel composite exhibited high energy storage density and excellent cyclic stability. 35 wt % is considered as the optimal addition amount of Y2O3 because of its highest energy storage density of 1986 kJ/kg after 10 cycles. CaY35 not only showed outstanding extended cyclic performance but also maintained a satisfactory energy storage density of about 1400 kJ/kg under harsh calcination conditions due to its increased Brunauer–Emmett–Teller specific surface area and enriched porosity through the N2 adsorption analysis. In addition, the extrusion-spheronization method was employed to granulate CaY35 powders into spherical pellets. The extrusion force during the granulation process led to the destruction of the sorbent structure to some extent, resulting in a slight decline in pellet performance. However, the granulation endowed the pellets with excellent mechanical strengths and they lost only 4.28 wt % of their initial mass after 7000 rotations in a fragility tester, which was of great significance for their cyclic practical applications.