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

• Published in: Environmental science & technology Vol. 40; no. 10; pp. 3388 - 3394
• Main Authors: Aelterman, Peter, Rabaey, Korneel, Pham, Hai The, Boon, Nico, Verstraete, Willy
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 15.05.2006
• Subjects: Applied sciences; Bacteria - isolation & purification; Bacteria - metabolism; Biodegradation, Environmental; Bioelectric Energy Sources; Bioreactors; Electric resistance; Electricity; Electricity generation; Electrodes; Electrons; Energy; Energy. Thermal use of fuels; Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc; Exact sciences and technology; Experiments; Ferrocyanides - chemistry; Fuel cells; Microbiology; Sewage - chemistry; Sewage - microbiology; Water Purification - methods; Series connection; Electrochemical properties; Voltage current curve; Ferrates; Performance; Microbiological engineering; Fuel cell
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es0525511

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 Ω. 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.