Thermochemical Energy Storage Based on Salt Hydrates: A Comprehensive Review

Tomasz Spietz (), Rafał Fryza, Janusz Lasek () and Jarosław Zuwała
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Tomasz Spietz: Institute of Energy and Fuel Processing Technology (ITPE), ul. Zamkowa 1, 41-803 Zabrze, Poland
Rafał Fryza: Institute of Energy and Fuel Processing Technology (ITPE), ul. Zamkowa 1, 41-803 Zabrze, Poland
Janusz Lasek: Institute of Energy and Fuel Processing Technology (ITPE), ul. Zamkowa 1, 41-803 Zabrze, Poland
Jarosław Zuwała: Institute of Energy and Fuel Processing Technology (ITPE), ul. Zamkowa 1, 41-803 Zabrze, Poland

Energies, 2025, vol. 18, issue 10, 1-81

Abstract: Thermal energy storage technologies are essential for balancing energy demand and supply. There are three main types: sensible heat, latent heat, and thermochemical energy storage. Among them, thermochemical energy storage offers the highest energy density (1–3 GJ/m 3 ) and long-term storage capability. Salt hydrates have attracted attention as energy storage materials due to their low cost, wide availability, and operating temperatures being well-suited for residential and low-temperature applications. This review focuses on the use of salt hydrates in sorption-based thermochemical energy storage systems. It summarizes the current state of knowledge, including screening studies of various salt hydrates, their thermodynamic and operational limitations, advantages, and performance in composite materials. This review also covers recent projects and common reactor designs used in TCES applications. Based on the literature analysis, the most promising salt hydrates for sorption-based TCES systems include SrCl 2 , SrBr 2 , K 2 CO 3 , MgSO 4 , MgCl 2 , and CaCl 2 . Despite the high theoretical energy density of many salt hydrates, future work should focus on experimental studies in large-scale reactor systems to better evaluate the practical discharge behavior of the energy storage system beyond theoretical hydration enthalpies or small-scale thermal analyses.

Keywords: energy storage; salt hydrates; sorption; porous matrix (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2025
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