Researchers at the Massachusetts Institute of Technology (MIT) say they have created a material that provides a new way to harvest, store and use solar heat.
The new material, a polymer film, can soak up the energy of the sun during the day, store it, then release it when needed at a later time when necessary, the researchers say.
Storing solar energy involves harvesting heat from the sun and storing it in the form of electricity. Unlike these existing technologies, MIT's transparent film saves the sun's energy in a chemical state, and a simple chemical reaction can subsequently release it.
Stored heat is dispersed over time even with good insulation, the researchers explain. However, when a chemical storage system is used, the energy is retained in a stable molecular configuration. A bit of light, heat or electricity is all that's needed to activate it.
In the film material, chemical compounds known as azobenzenes are altered at the molecular level when exposed to the sun's energy and maintain that altered state indefinitely.
Then a small stimulus such as a burst of temperature causes the compounds to revert to the original molecular state, releasing the stored heat. That release can warm up a surface by as much as 60 degrees Fahrenheit, the researchers say.
The polymer film could easily be integrated into everyday products like window glass or clothing or in industrial processes, they point out.
Chemical-based storage systems had been created before, but because they were liquid-based systems they "had limited utility in solid-state applications," says MIT postdoctoral researcher David Zhitomirsky.
The MIT effort is the first to use an inexpensive solid-state material that can be made using widely available manufacturing technologies.
The polymer film can be manufactured in a simple two-step process that would be "very simple and very scalable," says MIT graduate student Eugene Cho.
Other experts were quick to take note of the possibilities.
"This work presents an exciting avenue for simultaneous energy harvesting and storage within a single material," says Ted Sargent, a University of Toronto professor who was not involved in the research.
