“One of the main contributions of this work lays in the introduction of a completely novel “in situ” protocol for the composite material synthesis that consists in preparing porous cement with the salt already embedded within”Eliodoro Chiavazzo
Italian researchers have developed a new material that could help in the take-up of renewable energy-based systems. The material, which is based on inexpensive technology using a combination of cement, salt and water for thermochemical energy storage, can store heat over the summer months for use in winter, and could lead to a new class of composite materials.
With about 90% of the total energy used worldwide involving processes where thermal energy is either generated or manipulated, it is imperative that the time gap between the energy surplus and the peaks of demand are resolved. This makes it key to more effectively exploit renewable energy sources by integrating inexpensive storage systems to help balance usage.
The team, from Turin University and the Institute for Advanced Energy Technologies of the Italian National Research Center, has been exploring technologies that allow for storing of heat with high density over long time periods and without unacceptable losses. As reported in Scientific Reports [Lavagna et al. Sci. Rep. (2020) DOI: 10.1038/s41598-020-69502-0], they demonstrated the potential for producing heat through the hydration of salt present inside the pores of cement, an approach that compares well with most of the known materials regarding stored energy costs.
Similar to how in dissolving salt in a glass of water, some salts will heat the glass while others will cool it, instead of liquid water they used aqueous vapor without dissolving the salt, which interacts with the salt to produce heat. Once completely hydrated, it is possible to revert the salt to its starting state just by drying it, eliminating the surplus water.
The properly tuned cement-based host matrices in composite materials for thermochemical heat storage were shown to be viable and much cheaper for stored energy. The total cost of the used materials is very low, and the energy behavior is good – offering great stability, even after hundreds of heating/cooling cycles.
As team leader Eliodoro Chiavazzo told Materials Today, “One of the main contributions of this work lays in the introduction of a completely novel “in situ” protocol for the composite material synthesis that consists in preparing porous cement with the salt already embedded within”. The use of cement as a matrix, with its complex chemical composition and interactions, can be also useful to further understand the long-term behavior of sorbent composite materials.
The team now hope to introduce a systematic optimization procedure of the base components of the composite to further improve the materials, including for water uptake, heat release, temperature lift and also reducing cost of the stored energy while keeping within acceptable stability limits in terms of time and number of cycles.
"Combination of cement, salt and water towards cheaper thermochemical energy storage".