In the framework of thermochemical energy storage (TCES) in concentrating solar power (CSP) plants, the calcium-looping (CaL) process, carried out in fluidized bed reactors, is receiving increasing research interest due to the high energy density and the extremely low price, nontoxicity, and wide availability of natural CaO precursors. One of the main open challenges in CaL is represented by finding solutions to the progressive decline in the CaO carbonation conversion with the number of cycles, which is due to the sorbent deactivation caused by sintering and pore-plugging. In this framework, the reduction of the CaO particles size has been reported to improve the carbonation conversion and, therefore, the achievable energy density, by maximizing the availability of the sorbent surface exposed to the gaseous phase and hindering the natural loss of CaO mutlicyclic activity. However, the use of fine particles in fluidized bed reactors is challenging due to agglomeration, channeling and plugging phenomena.