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New Enzyme-Based Fuel Cell Produces Electricity from Hydrogen in Plain Air

26 March 2007

Fuelcellenzymes
Schematic representation of a bio fuel cell involving hydrogenase and laccase enzymes. Click to enlarge. Source: Armstrong Research Group

Researchers at Oxford University have developed an enzyme-based fuel cell that produces electricity from ordinary air spiked with small amounts of hydrogen. The new type of cell would be an inexpensive alternative to the costly platinum-based fuel cells that are a primary focus today.

The “bio fuel cell” uses an anode coated with oxygen-tolerant hydrogenases—enzymes from a naturally occurring bacterium that oxidize hydrogen in its metabolism—coupled with a cathode modified with the fungal oxygen reductase, laccase. Laccase catalyses the reduction of oxygen to water.

The enzyme-coated electrodes are placed inside a container of ordinary air with 3% added hydrogen.

The research established for the first time that it is possible to generate electricity from such low levels of hydrogen in air, according to Fraser Armstrong, the research leader.

Prototype versions of the cell produced enough electricity to power a wristwatch and other electronic devices. Armstrong foresees advanced versions of the device as potential power sources for an array of other electronic products that only require low amounts of power.

The technology is immensely developable. We are at the tip of a large iceberg, with important consequences for the future, but there is still much to do before this generation of enzyme-based fuel cells becomes commercially viable. The idea of electricity from hydrogen in air, using an oxygen-tolerant hydrogenase is new, although other scientists have been investigating enzymes as electrocatalysts for years. Most hydrogenases have fragile active sites that are destroyed by even traces of oxygen, but oxygen tolerant hydrogenases have evolved to resist attack.

—Fraser Armstrong

Platinum-based fuel cell technology is hampered by the cost of the metal—platinum is more costly than gold, with recent prices topping $1,000 per ounce. In addition, platinum catalysts are easily poisoned or inactivated by carbon monoxide that often exists as an impurity in industrially produced hydrogen. Carbon monoxide can be removed, but that further increases the cost of conventional fuel cells.

By contrast, naturally occurring hydrogenase enzymes can be produced at lower cost, with carbon-monoxide poisoning not being a problem. Since the hydrogenases are chemically selective and tolerant, they work in mixtures of hydrogen and oxygen, avoiding the need for expensive fuel-separation membranes required in other types of fuel cells. Hydrogenases are able to oxidize H2 at rates that are comparable to or higher than platinum-based catalysts, according to the researchers.

The biofuel cell uses enzymes from Ralstonia metallidurans, an ancient bacterium believed to have been one of the first forms of life on Earth. It evolved 2.5 billion years ago, when there was no oxygen in Earth’s atmosphere, and survived by metabolizing hydrogen.

One focus of Armstrong’s research is understanding how the active site of the R. metallidurans hydrogenase developed the ability to cope with oxygen as Earth’s atmosphere changed. That could enable scientists to adapt the chemistry in the active site into bio fuel cells that are more tolerant of oxygen. In the current version of the cell, the enzyme is not attached tightly to the electrode and the cell runs for only about two days. The researchers also are investigating the use of enzymes from other organisms.

The Armstrong Research Group at Oxford is working closely with Prof. Bärbel Friedrich, of the Humboldt University in Berlin, who is investigating the molecular biology of hydrogenases that can tolerate oxygen.

A paper on this research was presented at the 233rd national meeting of the American Chemical Society.

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March 26, 2007 in Biotech, Enzymes, Fuel Cells | Permalink | Comments (7) | TrackBack (0)

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Comments

To all those who said hydrogen fuel cells could never work.

I don't think anyone (who's reasonable) said they'd never work. The main reason for criticism has been their economics and difficulty of implementation (particularly storage and distribution) in comparison to some of their competition (BEVs, PHEVs and bio-fuels)

Its a low pwer fuel cell not something that would ever power a car. Still much like the ethanol fuel cell its a good tech to have.

The old phrase "may you live in interesting times" comes to mind. With today's technology we can come up with many new things more quickly than in the past. Some problem solutions may remain elusive, but when you have people from many fields like biology as well as physics working on a problem, you can come up with some interesting stuff.

"Prototype versions of the cell produced enough electricity to power a wristwatch and other electronic devices. Armstrong foresees advanced versions of the device as potential power sources for an array of other electronic products that only require low amounts of power."

This is absolutely what the world needs, a new power source for those damn wristwatches which lose power every, uh, can we say almost never? From my experience, what we really need is a better way of marking the buttons on my wristwatch and the watchband; these fade and wear out well before the battery dies. Excuse me for my sarcasm, but it appears that the Spring snows here in my part of Colorado have gone the way of the dodo bird. Global warming my have finally acheived its knockout blow to the Spring snows which used to provide a significant part of our snow pack. And we are talking about never, never land technology to power wrist watches?

40 Years ago, you would have thought current 'state of the art' computing technology was amazing. If you saw it today, you'd laugh. There has been a huge journey to get to where we are today, but people often take that journey for granted. They think that in order for new technology to be worthy of consideration in 2007, it must start off it's technological life at a level matching current technology.

This is such a flawed perception and people need to get over it. In all probability, nobody is going to discover a 'big bang' source of renewable energy. Scientists are going to discover small areas with potential and improve on them over time, just like the computer was improved over time.


Read "Prototype versions of the cell produced enough electricity to power a wristwatch". "Prototype" being the operative word.

Further on, read "We are at the tip of a large iceberg"


This technology could turn out to be a dud, yes. But it could also turn out to be something huge. Give the product time to mature please! Could you say about a newborn baby that "They will never make a good leader"?

The chip industry started with logic chips for the military. Then on to calculators and digital watches. As long as there is an application that can fund the growth of an innovative company, there is a chance that they can produce something even more useful in other applications.

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