Molecules Harness Sun’s Energy, Even in Absence of Sunlight

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Detractors of solar energy are quick to criticize that it doesn’t work at night or on cloudy days, but now a new innovation from scientists at MIT has taken a step toward changing that. They have developed a material which can absorb heat from the sun and store it to be available at the flip of a switch. The results have been published in Nature Chemistry.

The material is made from photoswitches: molecules capable of existing in one of two conformations. A stimulus, such as electric current or heat from the sun, causes the photoswitch to change from one form into the other. The new change is able to hold in the heat energy, until it is instructed through another stimulus to give up the heat and return to the prior relaxed configuration. That stimulus to make the molecules release the heat can be controlled, creating a system capable of emitting heat under very controlled conditions.

This system was first theorized about three years ago. Since that computer model, the team has spent years trying to create the functional material. There were considerable challenges with cramming enough molecules close together to achieve the necessary energy density. Eventually, the team found that the structure of the molecules allowed them to be packed in tighter than they originally thought, and the functional material worked much more efficiently than the computer model had predicted.

Since it is storing heat, heat can then be outputted fairly readily for cooking or heating rooms. This could be life altering to many people in developing areas of the world who do not have access to cooking fuel or who can only burn animal dung, which is bad for a host of reasons including reducing air quality. Not only would this solar material preserve the quality of the air by being a zero-emission system, but it also doesn’t require the use of any resources which could be limited.

Of course, the system isn’t perfect as it cannot convert the heat energy into electricity very efficiently. The team will also continue to refine the technology and determine how to easily manufacture it.

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