Recent Status and Prospects on Thermochemical Heat Storage Processes and Applications

Abstract

Recent contributions to thermochemical heat storage (TCHS) technology have been reviewed and have revealed that there are four main branches whose mastery could significantly contribute to the field. These are the control of the processes to store or release heat, a perfect understanding and designing of the materials used for each storage process, the good sizing of the reactor, and the mastery of the whole system connected to design an efficient system. The above-mentioned fields constitute a very complex area of investigation, and most of the works focus on one of the branches to deepen their research. For this purpose, significant contributions have been and continue to be made. However, the technology is still not mature, and, up to now, no definitive, efficient, autonomous, practical, and commercial TCHS device is available. This paper highlights several issues that impede the maturity of the technology. These are the limited number of research works dedicated to the topic, the simulation results that are too illusory and impossible to implement in real prototypes, the incomplete analysis of the proposed works (simulation works without experimentation or experimentations without prior simulation study), and the endless problem of heat and mass transfer limitation. This paper provides insights and recommendations to better analyze and solve the problems that still challenge the technology.

A new heat and cold storage system to enhance the thermal autonomy of residential buildings

“…The thermochemical storage, still in the phase of basic research, has the highest storage density potential and relies either on sorption processes or on reversible chemical reactions [8]. The sorption processes require complex systems of condensers, evaporators, absorbate and solution storage tanks.…”

“…The sorption processes require complex systems of condensers, evaporators, absorbate and solution storage tanks. The chemical reactions, used for high temperature generation, suffer from poor material stability and high operating cost [8]. PCMs have been studied since the 1970's [1,2] and benefit from an early maturity, high storage density and low loss.…”

Effects of porous carbon materials on heat storage performance of CaCl2 hydrate for low-grade thermal energy

“…10 During the charging step, thermal energy is converted into chemical potential by breaking the binding force between the compounds. 11,12 Compared with SHS or LHS technology, TES technology offers some unique characteristics including: high energy densities, ambient storage, long-term storage, transportability, heat pumping, and low capacity costs. 13 As far as volume efficiency is concerned, thermochemical heat storage is more favourable with great energy storage density that is approximately 8-10 higher than sensible energy storage, and 2 times higher than latent energy storage.…”

Optimization of the Coating Process of a Ca(OH)2‐Based Thermochemical Energy Storage Material

“…Due to the enormous storage potential, there are already first pilot tests to use TCES as storage systems for load balancing in district heating networks or as solar‐powered seasonal heat storage systems 6. Possible TCES systems 9, 10 can be found, for instance, within the groups of inorganic hydroxides 11, 12, carbonates 13, metal hydrides 14, or other reaction systems like ammonia 15 or sulfur trioxide 16.…”

“…One of the most promising TCES systems within the group of hydroxides is the well-researched system CaO/Ca(OH) 2 [10,12,[17][18][19]. The raw materials are available almost worldwide, can be stored stable for an arbitrary period of time, are environmentally compatible [9,18,[20][21][22] and cost efficient (on average 160 USD t -1 Ca(OH) 2 in the US in 2022 [23]).…”