Comparison of Thermochemical Heat Storage Materials

Abstract

Thermochemical heat storage (TCS) systems play a crucial role in ensuring the continuity of intermittent renewable energy sources, especially solar power. The compounds used include metal hydroxides, various carbonates, and metal oxides that can be reduced and re-oxidized. Heat is stored by being trapped in chemical bonds during reversible chemical reactions and is released again when those reactions proceed in reverse as needed. In thermochemical heat storage systems, material types show different benefits and limitations depending on operating conditions. This study examines and compares the materials employed for thermochemical heat storage in the literature. Metal oxide–based systems stand out for high-temperature industrial applications, while salt hydrates are preferred for medium- temperature building and seasonal storage applications. Sorption materials are more suitable for cooling and HVAC systems that operate at low temperatures. Composite materials, meanwhile, attract attention as hybrid solutions that balance performance and stability across these different approaches.