Researchers in India are combining solar energy generation and storage for easy use on the go.
If we are going to continue harvesting more of our energy from renewable sources such as solar, storage is the next big challenge. Promising candidates include supercapacitors, which are popping up in all sorts of everyday applications – from flashlights to road signs. These devices have a lifetime of up to 20 years, whereas batteries only last a few years.
Going a step further, researchers in India have developed a prototype that combines photovoltaic (PV) generation and a supercapacitor in one. Following exposure to the sun for four hours, the Amrita Smart solar tile can charge laptops and mobile phones in two hours, and store the energy for seven days – although the aim is to extend this capacity to 30 days.
"This should be thought of as the first product in its generation", says Dr Shantikumar Nair, Director of the Amrita Center for Nanoscience and Molecular Medicine in Kochi, "with future devices becoming thinner, even flexible, and with improved storage capacity."
Nair sees "tremendous opportunity for such technology". He explains: "There is a need for off-grid electricity, which PV can provide, but also for storing this energy for use when required. Having one device that does all this is better than separate constituents like the panel and the battery."
Professor Yury Gogotsi at Drexel Nanotechnology Institute, Philadelphia, agrees that combining solar energy generation and storage is a good idea (albeit not a new one): "In applications where space is restricted it is desirable to have a generation and storage device in one rather than, say, a panel and a separate battery."
There are challenges. Such as "getting sufficient energy density without making the device too bulky", says Gogotsi, who has worked on thin film carbon supercapacitors for integration with solar cells and other devices at Drexel Nanotechnology Institute, Philadelphia. "And there's the need to protect against overheating." But, he adds, "the bottom line is Amrita's prototype is a step in the right direction". – Sara Ver-Bruggen