Researchers analyse the beneficial uses of phase changing materials for thermal energy storage to help mitigate climate change effects.
As the world searches for practical ways to decarbonise our activities and mitigate associated climate change effects, approaches to alternative energy are hampered by the intermittent nature of energy sources, such as solar and wind.
One possible solution to help boost reliability and adoption of such renewable energy sources is improved energy storage capabilities. In the Journal of Applied Physics, a collaboration of researchers from Lawrence Berkeley National Laboratory, Georgia Institute of Technology, and the University of California, Berkeley, illustrate advances in understanding the fundamental physics of phase change materials used for energy storage.
Phase change materials
Phase change materials absorb thermal energy as they melt, and obtain that energy until the material is again solidified. Gaining a better understanding of the liquid state physics for this type of thermal storage may help to accelerate technology development for the energy sector.
“Modelling the physics of gases and solids is easier than liquids,” said co-author Ravi Prasher. “Gases are free moving, and solids merely vibrate, but liquids behave more like a solid when melting and more like a vapor as they heat up.”
This behaviour makes it difficult to model and predict storage-system behaviour during the phase change that is critical to its function.
Thermal energy storage advances
To take advantage of phase change phenomena of materials for thermal storage, material parameters, including molecular motion and entropy, must be mathematically described, so that behaviour and theoretical limits can be predicted.
The researchers illustrated a step toward this predictive power by discussing past literature and new developments in the field of liquid state physics.
“The amount of energy that gets stored during phase change depends on the entropy of melting,” explained Prasher. “Once you know how to predict the entropy change, you know how to design materials that will cater to specific needs.”
Developing high-performance thermal energy storage material is important, as heat energy is the dominant energy that is used in building and manufacturing. Thermal storage is also a safer option than many other forms of energy storage, as it does not have the capability to release stored energy rapidly and destructively in the case of a malfunction.
Finally, thermal storage holds promise for functioning at large scales and over long durations, and individualised and/or novel materials can be manufactured to suite specific needs. More sophisticated models are needed to further aid in the ability to screen and create materials for optimal thermal energy storage applications.