Fuel cell technology: Fuel from an ‘artificial leaf’

Visions of catchy titles danced in my head: “Alternative energy turns over a new leaf,” for example. It sounds like a perfect story for a world growing ever more skittish about the future of energy. (As Fukushima continues to radiate danger and fuel prices head into economy busting territory.) The idea is to produce energy using a device that mimics the photosynthetic abilities of nature – an artificial leaf.

The “leaf” in this case is a silicon-based square about the size of a large business card. Drop it into water with plenty of direct sunlight and its catalytic properties split the molecules of water (H20) into hydrogen and oxygen gas. Anyone who follows alternative energy will immediately recognize what this means – fuel cell. The hydrogen gas is the primary source of energy for fuel cells, one of the big hopes for the future of clean “green” energy.

Unfortunately, color me skeptical, not green.

There are labs all over the world working on various forms of artificial photosynthesis. This particular artificial leaf idea comes with good pedigree from the lab of Daniel Nocera at the Massachusetts Institute of Technology (USA). He got the idea from researchers at the U.S. National Renewable Energy Laboratory (Boulder, Colorado), who developed a similar device in 1998 but used platinum, or other similarly expensive materials for catalysts and which did not last a day. The achievement for the MIT lab was to use much less expensive materials, nickel and cobalt, to operate continuously and at a high level of output for around 45 hours. The key is that this ‘artificial leaf’ produces gasses that can be stored and used in a fuel cell system – there is no need for electrical storage such as a battery.

This sounds great and the researchers are not bashful about it:

“A practical artificial leaf has been one of the Holy Grails of science for decades. We believe we have done it. The artificial leaf shows particular promise as an inexpensive source of electricity for homes of the poor in developing countries. Our goal is to make each home its own power station.”

[Source: EurekAlert]

The claim is that the ‘leaf’ could provide up to 30 kilowatt-hours of electricity per day, roughly equivalent to the electrical use of an American household.

This would indeed be quite wonderful, revolutionary, in fact. I wish, however, that the accompanying press release and most of the coverage this has received would also emphasize that:

- This is a presentation of a concept (at the American Chemical Society convention), with a prototype catalytic device.
- The findings for the newest device are not yet published in a peer reviewed journal.
- This is not a working device in the sense that it hasn’t been paired with a functional fuel cell environment.
- A production-ready fuel cell based on this technology is years away (actually, the researchers do mention this).
- One of the known hurdles for all such technology is the ability to ‘scale,’ that is, can it be manufactured in large quantities?
- Like traditional solar cells, this device requires direct sunlight – what are the specific necessary operating conditions for long-term high output?

There are always questions about technology that supposedly has a major impact. Not addressing them squarely leads to skepticism. It’s a standing notion in science that extraordinary discoveries require extraordinary evidence. That level of detail and planning has not accompanied this announcement of technology.

Note these are reservations that should apply to any significant technology at this early stage of its development. In defense of Dr. Nocera and the researchers at MIT – who do have a good idea of science and technology requirements – the ‘artificial leaf’ has been in the works for several years, and practicality has always been the focus. It is also true that Dr. Nocera and MIT inked an agreement in October of 2010 with the Tata Group of India (the company that developed the world’s least expensive car) for further development of the concept. So somebody (big) is putting money where their mouth is. All to the good. The world sorely needs inexpensive, small-scale, minimal polluting sources of energy.

Research Spectrum

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