Power-Generation from Biorenewable Resources. Biocatalysis in Biofuel Cells.

This chapter examines the function of and challenges for biocatalysis in biofuel cells. Compared with chemical fuel cells, biofuel cells afford more fuel options, bio-compatibility, and mild operation conditions. Although the power density of biofuel cells is usually 2-3 orders of magnitude lower than that of chemical fuel cells, they are attractive for special applications such as implantable devices, sensors, drug delivery, microchips, and portable power supplies. Microbial biofuel cells also have great potential in digesting organic wastes and biomass for power generation. Exciting technical advances in the field of biofuel cells have recently emerged. Compared to noble metal-catalyzed fuel cells, biofuel cells offer ambient operation conditions and can eventually be cheaper as the production cost of the key biocatalysts continues to drop as a result of developments in genetic engineering. Biocatalysts are capable of catalyzing the oxidation of most of the conventional fuels. They are also efficient in oxidizing more complicated chemicals such as carbohydrates and various organic wastes for electricity generation. Biofuel cells afford a much broader range of fuel options. Hydrogen and methanol are the most popular fuels examined for general-purpose fuel cells. Other chemicals such as ammonia, hydrocarbons, ethanol, propanol, ethylene glycol, glycerol, cyclic alcohols, formic acid, and formate have also been investigated.