A team of researchers at the University of Oxford have developed an enzyme based biological fuel cell that takes oxygen and hydrogen from an atmosphere to power electrical devices. The enzymes used were isolated from bacteria that evolved naturally to use hydrogen in their metabolic process. The enzymes are highly selective and tolerant of gases that poison traditional fuel cell catalysts. The advantage is that the enzymes are a cheap and renewable alternative to expensive platinum catalysts normally used in fuel cells.
Professor Fraser Armstrong and his colleagues built a fuel cell consisting of two electrodes coated with the enzymes in a small gas tank containing air with a few percent added hydrogen. The fuel cell was used to power a digital watch and the researchers believe that this development marks a milestone in the development process to improve the power density and lifetime of the enzymes.
According to a NREL website, other researchers are attempting to develop microbes to produce hydrogen from water, but as they produce oxygen as well as hydrogen and the hydrogen-evolving microbes are oxygen sensitive, this limitation must be overcome before a biological fuel cell that is fed by nothing but water could be developed.
Milestone Achieved in the Development of Biological Fuel Cells, Newswise via Fuel Cell Today, April, 1, 2006
Hydrogen Production and Delivery, NREL R&D, Hydrogen and Fuel Cell Research website