A new heat storage material can help significantly improve the energy efficiency of buildings. Developed by researchers at Martin Luther University Halle-Wittenberg (MLU) and the University of Leipzig, it can be used to store excess heat and release it back into the environment when needed. Unlike existing materials, the new one can absorb significantly more heat, is more stable and is made from harmless substances. In the Magazine for Energy Storage the team describes the forming mechanism of the material.
The invention is a so-called shape-stabilized phase change material. It can absorb large amounts of heat by changing its physical state from solid to liquid. The stored heat is then released again when the material hardens. “Many people are familiar with this principle of hand warmers,” explains Professor Thomas Hahn of the Institute of Chemistry at MLU. However, Halle’s invention will not be used in coat pockets. Instead, it can be used by the construction industry as large panels that can be integrated into walls. It will then absorb heat during the sunny hours of the day and release it again later when the temperature drops. It can save a lot of energy: The researchers calculated that when the new material heats up, it can – under the right conditions – store up to 24 times per 10 degrees Celsius more heat than conventional concrete or wallboard.
Unlike hand heaters, the panels made from this material blend do not melt when they absorb heat. “In our invention, the heat storage material is enclosed in a solid silicate framework and cannot escape due to high capillary forces,” Hahn explains. Most importantly, the substances used in its production are environmentally friendly: harmless fatty acids such as those found in soaps and creams. Even the additives that give the material its strength and increased thermal conductivity can be obtained from rice husks.
In the present study, the team describes the steps involved in creating the structure of the material and how the different chemicals affect each other. For this, the team received support from a group of researchers led by Professor Kirsten Bacia of MLU, who used fluorescence microscopy to visualize the mechanism. “The knowledge we gain can be used to further optimize the material and to possibly manufacture it on an industrial scale,” says Felix Marske, who drove the development forward as part of his doctorate with Thomas Hahn. Until now, the material has only been produced in small quantities in the laboratory. In the future, it can be combined with other steps to make buildings significantly more energy efficient or to passively cool photovoltaic systems and batteries and thus increase their efficiency.
Material provided by Martin Luther University Halle-Wittenberg. Note: Content can be edited for style and length.