Silver is the Key

September 27, 2013 at 08:23

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The addition of silver has been shown to be an important additive for helping microbes turn sewage into power and to create bio-batteries.

The latest step in the quest for ‘clean electricity’ has shown that proteins on the surface of bacteria can produce an electric current by simply touching a mineral surface. It is possible for bacteria to lie directly on the surface of a metal or mineral and transfer electrical charge through their cell membranes. In theory, it should be possible to ‘tether’ bacteria directly to electrodes. With the process, microorganisms attached to the anode then start snatching electrons from organic compounds dissolved in the waste water to produce carbon dioxide and clean water.

All microbe-based batteries and fuel cells need a place to send electrons, a fact that has proved to be technically challenging. With some new research, scientists at Stanford University have replaced bubbling oxygen with a solid silver oxide that consumes electrons, making a more reliable, rechargeable bacterial battery. Silver possesses the highest electrical conductivity of any element and the highest thermal conductivity of any metal. Silver is found in native form, as an alloy with gold (electrum), and in ores containing sulfur, arsenic, antimony or chlorine.

Another advantage with silver it has a high efficiency in terms of the amount of power produced. The downside is that silver is relatively expensive and the cost would be high, should this be reproduced on an industrial scale.
The research has been published in the Proceedings of the National Academy of Sciences. The paper is titled “Microbial battery for efficient energy recovery.”