Oxford (UK) - British scientists outlined a method to recharge "biofuel cells" in air that contains a slightly elevated levels of hydrogen. Prototype version of such fuel cells have been built already and point towards a relatively inexpensive rechargeable fuel cell technology.
According to Fraser Armstrong and his research group at Oxford University, specially developed fuel cells can generate electricity from air than contains about 3% of hydrogen, which is just below the 4% mark that puts hydrogen into explosive territory. The biofuel itself uses hydrogenases, which are enzymes of naturally occurring (Ralstonia metallidurans) bacteria that use or oxidize hydrogen in their metabolism. Armstrong said that both electrodes of the cell are coated with the enzymes to achieve an electricity producing effect.
While the scientists said that the technology is "immensely developable," they explained that products that only require low amounts of power could be driven by such biofuel cells in the future. Prototype versions of the cell already produce enough power to run a "wristwatch and other electronic devices." A key advantage of hydrogen fuel cells is that they are fairly environmentally friendly as they produce water as their only waste. However, such fuel cells typically require a powerful catalyst, such as platinum which makes proton exchange membrane fuel cells expensive to manufacture. Armstrong said that hydrogenases can be produced at much lower cost than platinum-based catalysts. However, besides low power output, the researchers face several challenges with their biofuel cell technology, including durability of the device : The cell currently runs only for about two days.