Web Release Date: April 11,
Continuous Electricity Generation at High Voltages and Currents Using Stacked Microbial Fuel Cells
Laboratory of Microbial Ecology and Technology (LabMET), Ghent University, Coupure Links 653, B-9000 Ghent, Belgium
Received for review December 20, 2005
Revised manuscript received March 14, 2006
Accepted March 16, 2006
Abstract:
Connecting several microbial fuel cell (MFC) units in
series or parallel can increase voltage and current; the
effect on the microbial electricity generation was as yet
unknown. Six individual continuous MFC units in a stacked
configuration produced a maximum hourly averaged
power output of 258 W m-3 using a hexacyanoferrate
cathode. The connection of the 6 MFC units in series and
parallel enabled an increase of the voltages (2.02 V at
228 W m-3) and the currents (255 mA at 248 W m-3), while
retaining high power outputs. During the connection in
series, the individual MFC voltages diverged due to microbial
limitations at increasing currents. With time, the initial
microbial community decreased in diversity and Gram-positive species became dominant. The shift of the microbial
community accompanied a tripling of the short time
power output of the individual MFCs from 73 W m-3 to
275 W m-3, a decrease of the mass transfer limitations and
a lowering of the MFC internal resistance from 6.5 ± 1.0
to 3.9 ± 0.5 
. This study demonstrates a clear relation
between the electrochemical performance and the
microbial composition of MFCs and further substantiates
the potential to generate useful energy by means of MFCs.
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