Microbial Battery: A New Possibility of Self-Recharging Devices

Today's energy needs are an issue that is gaining much boom, ways of generating energy these days are very wide, in this one there are ways that may seem very strange to us but the human mind doesn't apparently has limits is only a matter of reinventing what nature already does by itself.

Among the alternatives to generate electricity is common to mention solar, wind, hydro, biomass, geothermal, nuclear, microbial cells, between many others. However it is last one sounds a little familiar with a slight change, the use of microorganisms. Harnessing energy from microorganisms sounds illogical, it is difficult to imagine in the mind, How something we can't see with the naked eye can produce more electricity than a conventional alkaline battery? these microorganisms allow us to use the oxidizing power generated when oxidize organic matter.

The idea is not as present, there are registers since 1911, when the botanist Michael Cressé Potter carried out the first attempt to use microorganisms to produce electricity, demonstrating that the breakdown of organic compounds by microorganisms is accompanied by the release of electricity that saw influenced by factors such as temperature, nutrient concentration of the media and the number of active microorganisms inducing the electricity production in microbial cells with a range of 0.3 to 0.5 Volt.

Microbial battery: microorganisms are attached to the carbon filaments of the battery

These results have been the basis of much research that handle electrochemical and engineering aspects that have allowed the development of microbial batteries as an alternative energy that can purify wastewater and recover the energy contained in it, if we compare with alkaline fuel cells in the market that can generate about 1.5 to 12 V, one of these can contaminate near 175,000 liters of water, and contain toxic substances such as zinc, manganese, bismuth, copper and silver, which produce various alterations human health while the microbial cells offer an option for direct power generation from oxidized donor and recovery of electricity from domestic wastewater, caring for the environment.

Pollution by alkaline baterries

 In 2013, Xie Xing introduced a microbial battery (MB) with modifications that promises to be more successful. In their MB prototyp the anode is colonized by microorganisms that oxidize domestic wastewater or glucose releasing electrons to an external circuit. The electrons enter a reoxidable silver oxide electrode solid-state (cathode), where the O2 is reduced making limited energy recovery by a voltage loss in this reaction. The molecular oxygen is not introduced into the battery and the ion exchange membranes is avoided which allows a high conversion efficiency of 49% power. The key of this device is the use in cathode functioning as a rechargable battery, in the next figure we can observe the operation of the microbial battery.

Schematic of two-step energy generation process using microbial batteries

This new contribution is not only to consider replacing domestic batteries whether not as a new deployment strategy batteries in cell phones or computers. Who has dreamed of having an electronic device that doesn't discharge? I would be very happy with something and maybe missing a lot for that but this progress is very promising so I don't rule out the possibility.