Researchers invent new way to store thermal energy
CAMBRIDGE, Massachusetts: MIT researchers have created material for a chemical heat “battery” that could release its energy on demand.
The new chemical composite could be used to store heat from the sun or any other source during the day in a kind of thermal battery, and it could release the heat when needed, for example for cooking or heating after dark.
A common approach to thermal storage is to use what is known as a phase change material (PCM), where input heat melts the material and its phase change – from solid to liquid – stores energy.
When the PCM is cooled back down below its melting point, it turns back into a solid, at which point the stored energy is released as heat. There are many examples of these materials, including waxes or fatty acids used for low-temperature applications, and molten salts used at high temperatures.
But all current PCMs require a great deal of insulation, and they pass through that phase change temperature uncontrollably, losing their stored heat relatively rapidly.
Instead, the new system uses molecular switches that change shape in response to light; when integrated into the PCM, the phase-change temperature of the hybrid material can be adjusted with light, allowing the thermal energy of the phase change to be maintained even well below the melting point of the original material.
The new findings, by MIT post-doctoral students Grace Han and Li Huashan and Professor Jeffrey Grossman, are reported in the journal Nature Communications. — Newswise