Acetic Acid Tolerance in Bio-Hybrid Fuel Cells

Given the high energy efficiency of some known organisms and their wide range of acceptable ‘food’ molecules, interesting possibilities for clean power generation have arisen.  A number of genera (such as yeast and some types of bacteria) are capable of using macroscopic electrodes in place of oxygen as electron acceptors.  These electrodes can facilitate the use of a Microbial Fuel Cell (MFC) to generate current.  MFCs hold much promise for clean energy and waste remediation, but they do have limitations. One of these is the rate of electron transfer at the cell membranes of the organisms being used.  The other may be the effect of electron transfer on the production of ethanol as a by-product.

Taking advantage of glucose oxidation into ethanol, bio-hybrid fuel cells were tested in direct ethanol fuel cells (DAFC). Although this technique is promising, a variety of variables have been shown to influence fuel cell performance. One of these variables is acetic acid production by ethanol oxidation at the fuel cell’s cathode.  Using amperometry and linear sweep voltammetry (LSV), the fuel cell’s reaction to a variety of acetic acid concentrations was examined. It was determined that low pH can aid the performance of the proton exchange membrane (PEM), but also degrades the performance of the platinum catalyst and can be catastrophic to fuel cell power output.