Fuel Cells: Microbial

A microbial fuel cell (MFC) is a new concept that marries fuel-cell technology to biofilm technology. A biofilm growing on the anode of a fuel cell oxidizes organic material and transfers the electrons to the anode. Microbial catalysis at the anode opens up the possibility to use any organic material as a fuel-cell fuel, not just H₂, as with a conventional fuel cell. Only recently have researchers shown that some bacteria are capable of oxidizing organic matter and transferring the electrons to an anode. An MFC could have an energy-capture efficiency as high as 75%, and one study showed 65% already. Thus, the MFC offers the highest potential energy-capture efficiency, as well as a much wider range of fuels than a conventional fuel cell. The science and engineering of MFCs are at the early stages. While the concept is demonstrated, the goal is to move it from an exciting scientific novelty to a practical technology.

A recent development in the MFC field is making H₂ at the cathode the energy output, instead of direct bioelectricity. This has been called a microbial electrolytic cell, or MEC. When coupled with a highly efficient H₂-based fuel cell, the H₂-generating MEC may offer the greatest potential and will be a major focus of our research effort on bio-hydrogen.