The layer-by-layer solar thermal fuel polymer film comprises three distinct layers (4 to 5 microns in thickness for each). Cross-linking after each layer enables building up films of tunable thickness.

Engineers from MIT have developed a new material could harvest sunlight by day and release heat on demand hours or days later.

Pocket full of sunshine: A new way to store solar energy

Picture for a moment, a world where your clothes could release heat on demand no matter the weather so you could be warm and comfy in a cool environment or if your windscreen could store enough energy to melt a layer of ice on those cold mornings? Well according to a team of researchers at MIT both of these possibilities could indeed be possible before long. Thanks to a new material, storing the suns energy during the day and releasing it as heat at a later stage when it’s needed could very well become a reality. This transparent polymer could be applied to different surfaces, such as window glass or clothing . The applications for such a polymer would revolutionise the way we use and store energy.( 2016)

Despite the sun being a virtually inextinguishable source of energy, it is only available half of the time i.e.: during the day. In order for the sun to become a major source of energy for human needs, a sustainable and efficient way to store it up for night and/or stormy day time usage has to be engineered. The majority of the methods focus on storing and recovering solar energy for electrical usage but due to this discovery one could provide a highly efficient system for storing the sun’s energy through a chemical reaction and releasing it later as heat.

The discovery made by MIT professor Jeffery Grossman, postdoc David Zhitomirsky, and graduate student Eugene Cho can be found in a paper in the journal: Advanced Energy Materials. According to the research team, the key to enabling prolonged, stable solar energy storage is not to store the heat it self but rather to store it as a chemical change. The principle of heat storage is that it will inevitably dissipate, despite the quality of insulation around it whereas a chemical storage system can in-fact retain the energy almost indefinitely in a stable molecular state, until such a time its release is triggered; either by a small jolt of heat or light or even electricity.


In the researchers’ platform for testing macroscopic heat release, a heating element provides sufficient energy to trigger the solar thermal fuel materials, while an infrared camera monitors the temperature. The charged film (right) releases heat enabling a higher temperature relative to the uncharged film (left).

Molecules with two configurations

The key is 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. Then, when triggered by a very specific temperature or other stimulus, the molecules snap back to their original shape, giving off a burst of heat in the process.

Such chemically-based storage materials, known as solar thermal fuels (STF), have been developed before, including in previous work by Grossman and his team. According to Zhitomirsky , those earlier efforts “had limited utility in solid-state applications” because they were designed to be used in liquid solutions and not capable of making durable solid-state films. The new approach is the first based on a solid-state material, in this case a polymer, and the first based on inexpensive materials and widespread manufacturing technology. ( 2016)

Publication: David Zhitomirsky, et al., “Solid-State Solar Thermal Fuels for Heat Release Applications,” Advanced Energy Materials, 2016; DOI: 10.1002/aenm.201502006

Full Article can be found here:

Original Source: David L. Chandler, MIT News

Article Source: Scitech Daily