Silver increases the effectiveness of bacterial batteries

New Scientist : Bacterial batteries that process waste to release electricity have been under development for several years. Current versions of the batteries use oxygen gas to collect the electrons that the bacteria release. However, gases are hard to control and can cause a variety of problems that reduce the batteries’ efficiency. Craig Criddle of Stanford University and his colleagues have created a new bacterial battery that uses solid silver oxide instead of the oxygen gas. The solid, which serves as the battery’s cathode, converts to silver as the oxygen collects the electrons. When the cathode is fully converted, it can be removed, processed back into silver oxide, and reused. The biggest downside is that silver is expensive, and that waste treatment plants would need large batteries and large amounts of silver. The larger batteries may also not be as efficient as Criddle’s demonstration, which converted 30% of the energy contained in the waste, comparable to other energy-harvesting technologies.