Operation of biological fuel cells

Unlike chemical fuel cells, biological fuel cells operate under mild reaction conditions, namely ambient operational temperature and pressure. They also employ neutral electrolyte and use inexpensive catalysts. In biological fuel cells, the catalyst is either a microorganism as simple as Baker’s yeast or an enzyme. Biological fuel cells convert the chemical energy of carbohydrates, such as sugars and alcohols, directly into electric energy. As most organic substrates undergo combustion with the evolutionof energy, bio-catalysed oxidation of organic substances by oxygen at the two electrode interfaces provides a means for the conversion of chemical energy into electrical energy. In normal microbial catabolism, a substrate such as carbohydrate is oxidized initially without participation of oxygen, while its electrons are taken up by an enzyme-active site, which acts as a reduced intermediate.