THERMOCHEMICAL ENERGY STORAGE AT HIGH TEMPERATURE FOR CONCENTRATED SOLAR POWER PLANTS, A CRITICAL REVIEW

Abstract

Thermal energy storage, known as TES, allows detaching the energy production from the demand. TES is especially appropriate to be used in concentrated solar power plants, where the energy is produced as heat. TES systems can be classified in three different technologies: sensible heat storage, latent heat storage and chemical heat storage. Currently, commercially available TES systems are based on sensible heat storage using molten salt stored in a double tank system. The other two technologies present a theoretical higher energy density but they are not mature yet to be commercially implemented. Among these systems, thermochemical heat storage has attracted the attention of the research community during the last decades and start to present promising results at relevant scale. The extremely high energy storage density and operation temperatures opens the door to a powerful and dynamic way of storing thermal energy for the plants of the future operating at higher temperatures. In this paper a review of the main experimental results concerning thermochemical energy storage for concentrated solar power plants is presented. A comprehensive review of metal oxides and redox reactions has been included, considering that the operation temperatures and the possibility of using natural air as the heat transfer fluid turns this approach into a very interesting solution for a new generation of concentrated solar power plants. Keywords: ?Thermal energy storage, Concentrated Solar Power, Thermochemical heat storage, Redox