Microbial Energizers: Fuel Cells That Keep on Going Microbes that produce electricity by oxidizing organic compounds in biomass may someday power useful electronic devices

H as this happened to you? You have a layover between flights, would like to use your computer and cell phone, but both sets of batteries are drained and the nearby electrical outlets are being used. What if you could instead recharge your electronic devices with a little sugar from the nearby coffee stand? With help from electricity-producing microorganisms, known as electricigens, some day you might have new options for ignoring the current “grid” by generating electricity in an alternative, environmentally friendly manner. Electricigens are recently discovered microorganisms with the ability to oxidize organic compounds to carbon dioxide while transferring electrons to electrodes with extraordinarily high efficiencies. Electricigens make it possible to convert renewable biomass and organic wastes directly into electricity without combusting the fuel, which wastes substantial amounts of energy as heat. Efforts to eliminate the inefficiencies of combustion are behind the recent interest in hydrogen fuel cells, which oxidize hydrogen and reduce oxygen to water while producing electricity in a controlled chemical reaction. With electricigens, however, it becomes possible to make microbial fuel cells, which offer potential advantages over hydrogen fuel cells. For example, hydrogen fuel cells require a very pure source of a highly explosive gas that is difficult to store and distribute. Furthermore, hydrogen is derived mainly from fossil fuel rather than renewable sources. In contrast, the energy sources for microbial fuel cells are renewable organics, including some that are dirt cheap.