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Biomimicry low solar cell creates hydrogen for fuel cell

Published on April 11th, 2013 | by Tina Casey


“Artificial Leaf” Makes Clean Energy From Dirty Water

April 11th, 2013 by  

What’s all this fuss about silly federal research projects? If one day in the not too distant future you can go to the dollar store, buy a thin, flat device the size of a playing card, dunk it in a quart of dirty bath water and use it to generate about 100 watts of electricity 24 hours a day, you can thank the Air Force. Along with other federal agencies, the Air Force Office of Scientific Research has been pouring funds into the development of an “artificial leaf,” a low cost solar-powered device that splits water into hydrogen and oxygen, for powering fuel cells.

Clean Energy From Dirty Water

We first noticed the artificial leaf concept a couple of years ago, when lead researcher Daniel Nocera (formerly of MIT, now at Harvard) called it “one of the Holy Grails of science.”

The device, which really is about the size of a playing card or a medium-sized leaf, is a stripped-down version of the process by which leaves create energy from sunlight and water.

Its simple design consists of a slim wafer of silicon coated with catalysts that break water molecules into hydrogen and oxygen gases, which can then be stored in tanks and used as fuel in hydrogen fuel cells.

The initial research resulted in a “practical artificial leaf” with commercial potential, but it required purified water. Otherwise, naturally occurring bacteria create a film on the wafer, which interferes with its efficiency and eventually prevents it from working altogether.

In the latest twist, which was just unveiled at a convention of the American Chemical Society, Nocera revealed a new iteration of the device that has the ability to keep chugging along in contaminated water.

The trick was to “tweak” the catalyst so that it creates a rough surface, preventing biofilm from forming. While that involves making part of the  catalyst fall apart, it also has the capability to heal and reassemble itself.

Low Cost Solar Power For Everybody

The artificial leaf is not particularly efficient, but the driving force behind Nocera’s research is not to create the most efficient device. The aim was to develop a simple, durable device that could help provide affordable, renewable energy to the billions of people (3 billion and counting) who currently don’t have reliable access to conventional energy and clean water.

Aside from general quality of life improvement, low cost devices like the artificial leaf could help provide sustainable alternatives to the widespread use of primitive cookstoves, which cumulatively have a significant impact on the global climate with a double whammy of “black carbon” emissions and deforestation.

With population movement already linked to climate change, affordable renewable energy devices will also play an important future role in relocation and disaster relief.

The combination of fuel production and energy storage also lends itself to any number of uses in the developed world that lack ready access to transmission lines and other forms of energy transportation.

Silly Federal Research Projects

That brings us right around to this whole idea of mocking federal research projects. It’s not a particularly new or original trend (National Geographic’s Carl Zimmer has a great article on the topic), but until recently it occurred within a social context of general respect for scientific method.

The current version is a different animal altogether, given the willful ignorance of settled science that has been aggressively promoted into the mainstream by political partisans, most infamously in the form of climate change “skepticism,” a fringe concept that made its way into the last presidential campaign and continues to bubble around certain members of Congress.

In that context, while the artificial leaf could find itself next in line for mockery, the last laugh you hear will probably be from Nocera and his team, which is already looking into using the device as a first step to creating liquid fuel.

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About the Author

specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Tina’s articles are reposted frequently on Reuters, Scientific American, and many other sites. Views expressed are her own. Follow her on Twitter @TinaMCasey and Google+.

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