Efficiency Of Solar-Powered Electrolysis Doubled

Having reached a solar-to-hydrogen efficiency of more than 24 percent, it may soon be feasible to harness the sun to split water.

AsianScientist (Oct. 13, 2015) – Researchers at the University of Tokyo and Miyazaki University have produced hydrogen under natural sunlight at an energy conversion efficiency of 24.4 percent, the highest ever achieved, using high efficiency solar cells to power water electrolysis. Their results, published in Applied Physics Express, is a significant step toward the substitution of fossil fuels with solar hydrogen.

The demand for hydrogen as a clean fuel for vehicles and other applications is expected to increase. Unfortunately, it is currently produced from fossil fuel. Conventional approaches to hydrogen production using solar-powered photocatalysts have achieved a solar-to-hydrogen energy conversion efficiency of less than ten percent, requiring improvements for real-world applications.

A team of researchers led by Associate Professor Masakazu Sugiyama and Project Professor Katsushi Fujii from The University of Tokyo and Associate Professor Kensuke Nishioka from Miyazaki University have now more than doubled the solar conversion efficiency to 24.4 percent.

They used concentrator photovoltaic (CPV) modules, which includes a photovoltaic cell using a high-quality semiconductor crystal similar to the ones for lasers and LEDs operating under the focal point of an optical lens. The solar-to-electricity conversion efficiency of this CPV module is as high as 31 percent. The researchers also reduced energy loss by improving the connection between the CPV modules and electrolyzers, resulting in a solar-to-hydrogen energy conversion efficiency above 24 percent.

“The CPV modules and the electrolyzers used in this experiment are commercially available and it is possible to produce hydrogen under sunlight at a high efficiency with an appropriate system design for each installation,” said Sugiyama.

“The CPV modules are comparatively expensive but if operated in countries with high solar irradiance it would be possible to generate solar electricity at low cost owing to the high energy conversion efficiency. In the near future, the cost of hydrogen produced by CPV modules and electrolyzes is expected to be below the target price of the United States Department of Energy of US$4 per kilogram.”

The article can be found at: Nakamura et al. (2015) A 24.4% Solar to Hydrogen Energy Conversion Efficiency by Combining Concentrator Photovoltaic Modules and Electrochemical Cells.


Source: University of Tokyo.
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