Fig. 7

Long-term performance of a vapor-fed bio-hybrid FC versus run time, in days. Ethanol was stripped from a 125 mL yeast fermentation and fed into a FC (with area of 2.68 cm²). The FC current density (at 200 mV) was measured at intervals of 1 s, and is plotted as a black line, using the left-hand y-axis. The ethanol concentration of the fermentation was measured just prior to most feedings, and is plotted as red dots, using the right-hand y-axis (The red line is only a visual aid; it is not data.)