According to a research done by an MIT team, a bacteria-powered fuel cell may be the answer to cell phone-charging blues in rural areas where lack of electricity is a major hassle. The BioVolt system uses grass, silage and other cellulose-rich material to provide fodder for the germs, whose digestion completes an electrochemical reaction that produces power. The output is very week; it will take six months to charge a cell phone with the current prototype of the device.

But we are sure, with improvements in the technicalities will increase the power output to a satisfactory level.
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