Imagine your clothing could release enough heat to keep you warm and cozy, allowing you to stay comfortable in a cooler room. Or, picture a car windshield that stores the sun's energy and then releases it as heat to make the ice on the windshield disappear.
According to a team of researchers at MIT, both cases may be possible before long, thanks to a new material that can store solar energy during the day and release it later as heat. This transparent polymer film could be applied to many different surfaces, such as window glass or clothing.
Solar energy is only available about half the time we need it — during daylight. For the sun to become a major power provider for human needs, there has to be an efficient way to save it up for use during nighttime and stormy days. Most such efforts have focused on storing and recovering solar energy in the form of electricity, but the new finding, by MlI professor Jeffrey Grossman, Postdoc David Zhitomirsky and graduate student Eugene Cho, could provide a highly efficient method for storing the sun's energy through a chemical reaction and releasing it later as heat.
The key to enabling long-term, stable storage of solar heat, the team said, is to store it in the form of a chemical change rather than storing the heat itself. But heat will disappear over time no matter how good the material around it is, so the team set up a chemical storage system that can keep the energy in a stable molecular configuration. When exposed to sunlight, the molecules can stay that way for long periods Then, when triggered (触发)by a very specific temperature or something else, the molecules return to their original shape , giving off heat in the process.
Such chemically-based storage materials, known as Solar Thermal Fuels(STF), have been developed before. But those earlier efforts were designed to be used in liquid solutions and not able to make durable (耐用的) 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 production technology.
