Researchers from the Massachusetts Institute of Technology (MIT) have developed a new material capable of storing solar energy during the day and release it as heat as needed.
The new transparent polymer film can be applied to many different surfaces including window glass or clothing,
According to the findings of MIT professor Jeffrey Grossman, postdoc student David Zhitomirsky, and graduate student Eugene Cho, the long-term stable storage of solar heat can be achieved by storing it in the form of a chemical change rather than storing the heat itself.
The researchers say that the chemical storage system can retain the energy indefinitely in a stable molecular configuration, until its release is triggered by a small jolt of heat (or light or electricity)
For the chemical storage to work, it needs a molecule that can remain stable in either of two different configurations.
When exposed to sunlight, the energy of the light kicks the molecules into their "charged" configuration, and they can stay that way for long periods, the researchers said.
The findings have been published in a paper in the journal Advanced Energy Materials.
University of Toronto professor Ted Sargent said: "This work presents an exciting avenue for simultaneous energy harvesting and storage within a single material."
In order to enable storing a useful amount of heat while ensuring its easy and reliable for manufacturing, the team developed materials, known as azobenzenes.
However, chemistry of the azobenzenes, which are capable of changing their molecular configuration in response to light, was modified by the researchers to improve its energy density.
Sargent: "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 work has been backed by a Natural Sciences and Engineering Research Council (NSERC) Canada Banting Fellowship and BMW.
Grossman said that the research team is currently working on the technology to improve the film’s properties including its transparency.
Although the new polymer material currently has ability to produce heat of about 10 degrees Celsius, the team is planning to improve its capacity to 20 degrees.
Image: The layer-by-layer solar thermal fuel polymer film. Photo: Courtesy of the researchers/ Massachusetts Institute of Technology.