MIT scientists develop polymer that harvests solar energy during day and releases heat at night

New Polymer Stores Solar Energy During Day And Releases Heat At Night-2

With countries slowly increasing their solar power capacity, researchers are actively looking for ways to develop efficient energy storage systems. A team of MIT scientists, for instance, has created an entirely new material that is capable of storing solar energy during daytime, and later releasing it as heat when needed. Unlike similar research, however, the study marks the first time that scientists have built a solid-state substance, in the form of transparent polymer film, which could be applied to a variety of surfaces, including clothing and windows.

Despite being an inexhaustible source of clean energy, the sun is not available in the night or during cloudy days. At present, energy storage systems focus mainly on harvesting and preserving solar power in the form of electricity. The new research, recently published in the Advanced Energy Materials journal, deals with a more efficient method, involving a specific chemical reaction that generates heat instead of power. Speaking about the project, Ted Sargent of the University of Toronto said:

This work presents an exciting avenue for simultaneous energy harvesting and storage within a single material. The approach is innovative and distinctive.

According to Jeffrey Grossman, a professor at MIT, and his team, the newly-developed chemical storage system ensures long-term, stable retention of sun’s energy, thus reducing loss of heat through dissipation. Central to the technology is a special molecule that remains stable in two specific configurations. Firstly, exposure to direct sunlight kicks these molecules into a “charged” mode, in which they can retain the solar heat for long periods of time. Later, in the presence of a particular trigger – like heat, electricity or light – the particles jolt back to their original configuration, releasing heat in the process.

New Polymer Stores Solar Energy During Day And Releases Heat At Night-1

While materials that store energy through chemical reaction, also called solar thermal fuels (STF), have been around for quite some time, such substances have until now existed mainly as liquid solutions. In the current research, the scientists have managed for the first time to create a durable, solid-state material that is inexpensive and also incredibly easy to manufacture. In addition to its remarkable energy storage capacity, this transparent polymer can be “incorporated into many different materials”, such as glass and fabric.

To develop the film, the team tweaked the properties of a special class of materials, known as azobenzenes. Capable of altering their molecular configuration when exposed to light of specific wavelengths, these substances can also be simulated with the help of heat, forcing them to return to their original configuration while releasing the stored energy as heat. To enhance its energy density, the researchers modified the material’s internal chemistry, including its responsiveness to thermal stimuli as well as its ability to form uniform, smooth layers.

The substance, the scientists believe, could have a range of applications. Being highly transparent, it could be used for de-icing windshields. When placed between two layers of glass, the material could help melt away the ice from car windows during the winter months. What is more, the polymer could be used to create clothing that keeps you warm by releasing tiny amounts of heat. This could in turn reduce the energy spent on central heating systems.

That is not all, however. The team is currently working to further improve the material’s properties, including its transparency and heat releasing capacity from 10°C up to 20°C. The technology could help increase the driving range of electric cars, by reducing the energy spent on heating during cold weather. Sargent added:

The approach is innovative and distinctive. The research is a major advance towards the practical application of solid-state energy-storage/heat-release materials from both a scientific and engineering point of view.

The research was conducted with the help of funding from German carmaker BMW and NSERC Canada Banting Fellowship.

Via: MIT News

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