LiOH and energy transition: key material for thermal storage

Thermal energy, or heat, is the earliest form of exogenous energy exploited by humans following the domestication of fire. Alongside pressure, heat remains a dominant transformation process in industrial operations. Heat can either be used directly, converted into electricity, or stored. Storage involves retaining a quantity of matter containing energy or a quantity of energy produced, for a later use. The aim is ensuring a balanced production/consumption relationship to optimise costs by reducing losses. Today, heat storage technologies are recognised among the most promising approaches for deploying an “intelligent” energy mix, incorporating greater proportions of renewable energy resources.

On a macroscopic scale, three physical principles allow some of materials storing (or releasing) heat without their decomposition :

– sensible heat $Q_{\mathrm{ s}}={\displaystyle {\int }_{T_{\mathrm{i}}}^{T_{\mathrm{f}}}V\rho \mathrm{\hspace{0.17em}}{C}_{\mathrm{sp}\mathrm{.}}^{\mathrm{l}}\left(T\right)\mathrm{d}T}$ which occurs during heating (or cooling) within a given temperature range,

– latent heat $Q_{\mathrm{ L}}=L=m\mathrm{\hspace{0.17em}}\mathrm{\Delta }{H}_{\mathrm{s}\rightleftarrows \mathrm{l}}$ which is exchanged at near-constant temperature during phase transitions (solid/solid, solid/liquid, liquid/gas and so on and so forth) in the so-called “Phase Change Materials (PCMs)”,

– thermochemical heat related to the dissociation/recombination of, at least, two materials during endothermic and exothermic thermochemical reactions, typically involving solid-gas transformations.

Sensible heat storage, historically the most widely employed method, is also the least expensive. Even before our era, the Romans use the “hypocaust”, a precursor of central heating systems powered by charcoal. This system circulated hot air beneath the floor, raising room temperature up to 30°C. A suspended floor, known as the “suspensura”, comprising a thick mortar layer of crushed tiles and lime, ensured optimal...