Concurrent Control of Power Overshoot and Voltage Reversal with Series Connection of Parallel-Connected Microbial Fuel Cells

One in four microbial fuel cell (MFC) units suffers from power overshoot. Series connection of the unit to a high-current-producing unit showed significant current loss (57%) due to power overshoot and the resultant voltage reversal. To concurrently control the power overshoot and voltage reversal, the two MFC units in series were converted to parallel connection, and this was then connected in series with another parallel-connected MFC group. The current loss for series connection of the two parallel-connected MFCs was as small as 3% compared to the sum of the maximum current of the four individual MFC units, without power overshoot; the anode potentials in the units were kept low between -0.24 V and -0.10 V at which electrochemically active bacteria can be easily grown. These results show that series connection of parallel-connected MFCs could be a readily applicable way for concurrently controlling the power overshoot and voltage reversal in MFC systems.