Researchers have developed a hydrogen fuel cell that uses enzymes to power real-world devices. The enzymes used are isolated from naturally occurring bacteria that have evolved to use hydrogen in their metabolic process. The unique features of these enzymes are that they are highly selective and tolerant of gases that poison traditional fuel cell catalysts, such as carbon monoxide and hydrogen sulphide. Since the enzymes can be grown they represent a cheap and renewable alternative to the expensive platinum based catalysts used by others in hydrogen fuel cells. Dr Roger Welch from University of Oxford said: "We are delighted to see the invention powering a useful device, in this case a digital watch, and believe that this marks a milestone in the development process to improve the power density and lifetime of the enzymes. We are very excited about the commercial and environmental benefits of these latest developments since it has the potential to provide the world with a clean and cost effective way of locally generating electricity".