Continuous Electricity Generation at High Voltages and Currents Using Stacked Microbial Fuel Cells

摘要

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 Wm~(-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 tOMEGA.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.