A review on metal halide–ammonia thermochemical seasonal sorption energy storage systems

Energy storage has been proposed as a promising solution to reduce the mismatch between the energy supply and demand. Research on thermochemical sorption energy storage (TSES) has demonstrated considerable interest in thermal energy storage system and heat transforming processes used in applications of solar energy storage, space heating, industrial heat recovery, and heat upgrade during the past 20 years. TSES is the only promising method to store energy for long-term/seasonal periods without any energy losses. However, TSES system is more complex and thus has not yet been developed commercially. So, more efforts are required to bring this technology to the market. TSES is the most recent thermal energy storage technology in recent decades, and it is still under investigation in laboratories. Sorption materials are the basis for developing TSES systems; however, it has the drawbacks of agglomeration and swelling; to address this issue, porous heat transfer matrixes using expanded natural graphite (ENG) have recently been proposed for improving mass and heat transfer by solidified composite adsorbents. So, the techniques of making composites of inorganic salts for TSES systems are presented in detail. Different from previous reviews, this review article focuses on various solid–gas thermochemical seasonal sorption and resorption energy storage systems based on metal halide–ammonia and consolidated composite metal halide–ammonia working pairs. This paper provided a state-of-the-art review on the progress of the latest studies and projects of theoretical and experimental chemisorption energy storage systems. Basic concepts, Clapeyron diagram, and selection criteria of storage materials of TSES systems were also presented.