A Review: Progress in Thermochemical Energy Storage Based on CaCO ₃ /CaO Materials for Concentrating Solar Power

Calcium‐based materials are widely recognized for their low cost and high energy density, and thermochemical energy storage (TCES) using calcium looping (CaL) has demonstrated greater potential than other high‐temperature energy storage systems in concentrated solar power (CSP) applications. However, the practical implementation of CaL‐CSP systems is still hindered by two critical factors: the complex design of solar reactors and the sintering‐induced deactivation of CaCO 3 /CaO particles during repeated cycles. To provide targeted solutions to these challenges, this review critically evaluates the performance and limitations of various solid–gas reactors, including fixed‐bed, entrained‐flow, rotary, and fluidized‐bed designs—under both direct and indirect solar irradiation modes. Particular attention is given to the need for improving solar energy absorption and conversion efficiencies, as well as resolving issues such as ash deposition, erosion, and clogging within reactor systems. In addition, recent advancements in CaCO 3 /CaO TCES technologies are summarized, with a specific focus on performance‐enhancing strategies such as dopant modification, precursor selection, particle size optimization, and optimized calcination conditions. Future research may further explore the introduction of novel dopant elements and the optimization of material preparation processes to enhance multicycle stability and storage efficiency.