Researchers at Lancaster University in the UK studied a crystalline material – a solid material with parts such as atoms, molecules or ions arranged in a highly ordered microscopic structure – and discovered that it has properties that make it possible to capture solar energy. The energy can be stored for several months at room temperature, and it can be released on request in the form of heat.
Solar energy storage
With further development, these materials can offer the potential to capture solar energy during the summer months and store it for use in the winter when less solar energy is available.
This would be invaluable for such things as heating systems in off-grid systems or remote locations or as an environmentally friendly supplement to conventional heating in homes and offices. It can potentially also be produced as a thin coating and applied to the surface of buildings.
The study, entitled “Long-term storage of solar energy under ambient conditions in a MOF-based solid ̵
How it works
The crystalline material is based on a type of “metal-organic framework” (MOF), which consists of a network of metal ions – atoms or molecules with a net electrical charge – bound by carbon-based molecules to form 3D structures. MOFs are porous so that they can form composite materials by hosting other small molecules in the structures. MOF composite is a solid, so it is chemically stable and easily contained.
The Lancaster research team wanted to find out if a MOF composite known as DMOF1, previously developed by a research team at Japan’s Kyoto University, could be used to store energy. It had never been investigated before.
The MOF pores were loaded with molecules of azobenzene, a compound that strongly absorbs light. These molecules act as light switches that can change shape when an external stimulus, such as light or heat, is applied. The researchers exposed the material to UV light, which caused the azobenzene molecules to change shape into a strained configuration inside the MOF pores, like a bent spring. The narrow MOF pores trap the azobenzene molecules in their strained form, so that the potential energy can be stored for long periods at room temperature.
When external heat is applied as a trigger to “switch” the state, the energy is released again, like a spring that breaks straight. This provides heat that can be used to heat other materials.
The exciting part is that further tests showed that the material was able to store energy for at least four months.
Dr. John Griffin, co-lead researcher of the study, said:
The material works a bit like phase-shifting materials, which are used to supply heat in hand heaters. While hand warmers need to be heated to charge them, the nice thing about this material, however, is that it captures ‘free’ energy directly from the sun. It also has no moving or electronic parts, and there is no loss involved in storing and releasing solar energy.
We hope that with further development we will be able to create other materials that store even more energy.
The next step is to investigate other MOF structures as well as alternative types of crystalline materials with greater energy storage potential.
Innovations like these are urgently needed as we are rapidly shifting to green energy and away from fossil fuels. Imagine having solar panels and the ability to store solar energy that came from these panels months.
For a game changer who would be in the energy world, and especially for people who live in seasonal climates, such as in Northern Europe, where it tends to be sunny in summer and gray in winter.
This is a very exciting development, and definitely one to look at to see what the next step forward is.
Photo: Pixabay / Pexels.com
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