Energy & Power
Have EPFL and CSEM cracked simple solar energy storage via hydrogen?
By Anthony Capkun
August 29, 2016 – One solution for storing solar energy for periods when the sun doesn’t shine is to convert it into hydrogen through water electrolysis. The idea is to use the electrical current produced by a solar panel to split water molecules into hydrogen and oxygen. But it’s not as easy as it sounds.
Hydrogen can be stored for future use to produce electricity on demand, or even as a fuel, but while different hydrogen-production technologies have provided promising results in the lab, they are still too unstable or expensive, and need further development to go commercial.
So, using commercially available solar cells and none of the usual rare metals, researchers at École polytechnique fédérale de Lausanne and Centre Suisse d’Electronique et de Microtechnique designed a device that, they feel, outperforms in stability, efficiency and cost.
The approach taken by EPFL and CSEM researchers is to combine components that have already proved effective in industry. Their prototype is made up of three interconnected, new-generation, crystalline silicon solar cells attached to an electrolysis system that does not rely on rare metals.
The device is able to convert solar energy into hydrogen at a rate of 14.2%, and has already been run for more than 100 hours straight under test conditions. Their method is published in the Journal of The Electrochemical Society.
“A 12-14 m2 system installed in Switzerland would allow the generation and storage of enough hydrogen to power a fuel cell car over 10,000 km every year,” said Christophe Ballif, who co-authored the paper. In terms of performance, the researchers say this is a world record for silicon solar cells and for hydrogen production without using rare metals. It also promises a high level of stability.
“We wanted to develop a high-performance system that can work under current conditions,” said Jan-Willem Schüttauf, a researcher at CSEM and co-author of the paper. “The heterojunction cells that we use belong to the family of crystalline silicon cells, which alone account for about 90% of the solar panel market. It is a well-known and robust technology whose lifespan exceeds 25 years.”
PHOTO: The device is able to convert solar energy into hydrogen at a rate of 14.2%, and has already been run for more than 100 hours straight. Courtesy Infini Lab/EPFL.