Researchers at Chalmers University in Sweden and Shanghai Jiao Tong University have come up with a technique for harvesting, storing and transmitting solar energy, and then extracting electricity from it. All this would be possible without the use of conventional PV cells or batteries.
Using MOST (Molecular Solar Thermal Energy Storage Systems) technology, the researchers succeeded in devising a method for storing solar energy. Energy as chemical energy within a special type of molecule, for up to 18 years. This molecule changes its chemical properties when it comes in contact with sunlight and stores some of that energy in new chemical bonds. This chemical energy can then be released in the form of heat energy with the addition of a catalyst where appropriate. The device can be used to store solar energy when sunlight is available and to provide thermal energy when it is not.
“The purpose of the project is to store solar energy into chemical energy inside organic molecules. And later when we want to use the stored solar energy, it is released as heat. And the next step was to convert this stored energy into electricity,” Zhihang Wang, a postdoc at Chalmers University in Sweden and lead author of the paper. The chip-based device has been used to convert the emitted thermal energy into electrical energy, albeit in the nanowatt range. This new technology is documented in a separate paper, “Wafer-Scale Solar Thermal Electric Power Generation,” published in Cell Reports Physical Science. The researchers envision many uses for the MOST combined system and new solution for wafer-scale electricity generation.
This combined system can also be useful in locations near the North Pole or the South Pole, which get continuous months of sunlight followed by months of darkness. In such cases, most technologies can be used to store solar energy when sunlight is present, and release it during the months when it is not there.
While the technology is still in its infancy, it holds a lot of promise in a variety of applications. For example, Wang didn’t rule out the possibility of using the chip-scale thermal electricity harvesting device in mobile devices, where it can repurpose the heat from the device’s internals and convert it back into electricity. However, such an application lies outside the research interests of the team.