Bioengineering
how do biological fuel cells work?
All living systems are in a sense a "biological fuel cell" because they convert compounds into energy. What I think you mean is how do man-made fuel cells use organic biological catalysts to convert sugars and alcohols to electricity. All fuel cells use a catalyst and two electrodes. When molecules are oxidized there is always a transfer of electrons. Biological fuel cells use enzymes to as catalysts to lower the activation energy of the oxidation process. The fuel is an organic molecule like methane, alcohol, methanol, or propanol, or a simple sugar like glucose. The oxidation takes place with 1/2 of the oxidation reaction happening at each electrode to force the electrons to flow. I hope this answer is what you were looking for.