A New Way to Store Thermal Energy

Estimated reading time: 4 minutes

“What we are doing technically,” Han explains, “is installing a new energy barrier, so the stored heat cannot be released immediately.” In its chemically stored form, the energy can remain for long periods until the optical trigger is activated. In their initial small-scale lab versions, they showed the stored heat can remain stable for at least 10 hours, whereas a device of similar size storing heat directly would dissipate it within a few minutes. And “there’s no fundamental reason why it can’t be tuned to go higher,” Han says.

In the initial proof-of-concept system “the temperature change or supercooling that we achieve for this thermal storage material can be up to 10 degrees C (18 F), and we hope we can go higher,” Grossman says.

Under a dark-field microscope, the microscale environment shows the rapid crystal growth can easily be monitored. (Grossman Group at MIT)

Already, in this version, “the energy density is quite significant, even though we’re using a conventional phase-change material,” Han says. The material can store about 200 joules per gram, which she says is “very good for any organic phase-change material.” And already, “people have shown interest in using this for cooking in rural India,” she says. Such systems could also be used for drying agricultural crops or for space heating.

“Our interest in this work was to show a proof of concept,” Grossman says, “but we believe there is a lot of potential for using light-activated materials to hijack the thermal storage properties of phase change materials.”

“This is highly creative research, where the key is that the scientists combine a thermally driven phase-change material with a photoswitching molecule, to build an energy barrier to stabilize the thermal energy storage,” says Junqiao Wu, a professor of materials science and engineering at the University of California at Berkeley, who was not involved in the research. “I think the work is significant, as it offers a practical way to store thermal energy, which has been challenging in the past.”

The work was supported by the Tata Center for Technology and Design within MIT’s Energy Initiative.

• < Previous Page