A Potentially Cheap Way to Store Solar | MIT Technology Review

A Potentially Cheap Way to Store Solar | MIT Technology Review



A Potentially Cheap Way to Store Solar | MIT Technology Review



Researchers have developed a device that cheaply and efficiently converts the energy in sunlight into hydrogen, which can be used as a fuel and is easily stored.

Michael Graetzel, who directs the Laboratory of Photonics and Interfaces at the Ecole Polytechnique in Lausanne, Switzerland, along with colleagues in Korea and Singapore, built a device that uses electricity and catalyst materials to make hydrogen and oxygen from water. This new “water splitter,” as such devices are known, is highly efficient, uses cheap and abundant materials, and is easy to make.

Researchers have been pursuing solar-powered water splitting for decades, and while they’ve shown great performance in one or two parts of such a device, no one has built a complete system that’s practical.

The device uses novel, relatively high-voltage solar cells to generate the needed electricity, along with inexpensive new catalyst materials based on nickel and iron for two electrodes—one produces hydrogen and the other makes oxygen.

The solar water splitter stores 12.3 percent of the energy in sunlight in the form of hydrogen. That might seem like a small amount, but consider that most solar cells convert only 16 percent of the energy in sunlight into electricity, without the added step of turning that energy into easy-to-store hydrogen.

More work is needed before the device can be practical. Researchers aren’t sure why perovskite materials degrade quickly, but they’ve been making progress—such as by adding a layer of carbon or improving the way the solar cells are sealed against the elements. Researchers recently demonstrated a perovskite solar cell that lasted over a month.