Energy sustainable advanced materials

Energy storage materials and devices can reversibly store and release energy in different forms, which not only facilitates the economical conversion of energy, but also provides a balance between energy demand and supply, especially for renewable energy sources. In the TES system, thermal energy can be stored in PCMs via latent heat or in molten salts via sensible heat. Sensible heat is stored or retrieved when the TES medium increases or decreases its temperature over a temperature span whilst the latent heat of the TES medium is stored or retrieved in the process of phase transition undergoing no change in temperature. Besides, an indirect TES method called thermochemical energy storage in which a second fuid is needed to transfer heat to enable the reversible chemical storage process can also help store thermal energy with very high effciency. The TES system is applicable to be integrated into different applications categorised by low, medium and high temperature TES applications. Low and medium temperature TES applications mainly involve heating/cooling facilities at spatially comfort temperature or a little higher, such as solar water heating and air heating. High-temperature TES systems are usually incorporated in CSP plants to smooth the fuctuations of electricity demand between peak and off-peak hours in a day and minimise the impact of the intermittence as well as improve the energy security and effciency. Furthermore, a TES system designed primarily for storage of solar energy is not necessarily restricted to that source, but can also be used, for example, to harvest industrial waste heat and geothermal energy.