The so-called "artificial leaf" is continuing to grow up, with an announcement this week at the American Chemical Society meeting that the device can essentially heal damage it sustains during energy generation processes on its own. This would allow Sun Catalytix's device—a "catalyst-coated wafer of silicon"—to run in the impure, bacteria-laden water found out in the world instead of just in pristine laboratory conditions.
The artificial leaf actually mimics only a part of the photosynthetic process found in plants. Drop the leaf into some water and expose it to sunlight, and the catalysts on its surface break down water into hydrogen and oxygen. Those bubbling gases can be collected and stored to be used as energy.
"We figured out a way to tweak the conditions so that part of the catalyst falls apart, denying bacteria the smooth surfaced needed to form a biofilm. Then the catalyst can heal and re-assemble," said Daniel Nocera, founder of Sun Catalytix and a professor at MIT, according to a press release.
The company has been touting the leaf as a cheap and easy solution to global issues of energy poverty. Nocera says that as many as 3 billion people lack access to "traditional electric production and distribution systems," and that a simple device one drops in a bucket of water—even dirty water, with the latest development—could provide standalone electricity to those multitudes. A couple of years ago, the company's chief technology officer Tom Jarvi told me a bit more cautiously that because "the inputs are light and water, and the output is fuel, one can certainly see the applicability of something like that to the developing world." The economics of really reaching such an audience are probably still in question, and there is still a step missing: convert the fuel the leaf creates into something readily usable in generators or even cars. The leaf is also relatively inefficient, well below 10 percent, compared to 15 to 20 percent efficiency for solar panels.
Still, back in 2011 I wrote this about the Sun Catalytix leaf:
Jarvi says the company expects to be able to bring the device to the point where a kilogram of hydrogen could be produced for about US $3. Given that a gallon of gasoline contains about the same amount of energy as 1 kg of hydrogen, as long as gas prices stay north of $3 per gallon, this would make a cost-effective fuel source.
Let's see, what have U.S. gas prices done since then? Okay: never dropped below $3.22 and scared $4.00 once or twice. Looks like we're still on track there.