Portland, Ore. -- Have you ever wondered why all the ingredients for fuel--hydrogen and oxygen--can't be harvested from air? Oxford University researchers wondered, too. In searching for the answer, the team discovered living enzymes that had already evolved to harvest hydrogen and oxygen from air. By fashioning a battery anode from a metal impregnated with that microbe, the researchers were able to demonstrate a biofuel cell with enough capacity to power a digital watch.
"Our technology has broad applications where cost is a major issue, clean fuel sources cannot be guaranteed and instant power is required," said Oxford professor Fraser Armstrong.
The team used two enzymes. One was a catalyst for the anode, which harvests hydrogen by freeing its electrons to flow out the anode to the load. A second enzyme on the cathode uses the return line from the load to bond oxygen to the leftover fuel's free hydrogen.
The biofuel cell costs less than a conventional fuel cell because it does not require a membrane separating the anode from the cathode chambers. Since the enzymes coating the anode and cathode are extremely selective, they can share the same electrolyte chamber, like a lead-acid battery. And the metals also don't have to be the expensive platinum that is used in conventional fuel cells. To power the cell, however, the researchers had to add a small amount of hydrogen to normal air.
The University of Oxford's technology transfer company, Isis Innovation Ltd., is currently shopping the technology around in an attempt to find a manufacturing licensee.
This demonstration "marks a milestone in the development process to improve the power density and lifetime of the enzymes," said an Isis Innovation spokesman, Roger Welch. These developments "have the potential to provide the world with a clean and cost-effective way of locally generating electricity."