Alternate Charging and Discharging of Capacitor to Enhance the Electron Production of Bioelectrochemical Systems

Abstract

A bioelectrochemical system (BES) can be operated in both "microbial fuel cell" (MFC) and "microbial electrolysis cell" (MEC) modes, in which power is delivered and invested respectively. To enhance the electric current production, a BES was operated in MFC mode first and a capacitor was used to collect power from the system. Then the charged capacitor discharged electrons to the system itself, switching into MEC mode. This alternate charging and discharging (ACD) mode helped the system produce 22-32% higher average current compared to an intermittent charging (IC) mode, in which the capacitor was first charged from an MFC and then discharged to a resistor, at 21.6 Ω external resistance, 3.3 F capacitance and 300 mV charging voltage. The effects of external resistance, capacitance and charging voltage on average current were studied. The average current reduced as the external resistance and charging voltage increased and was slightly affected by the capacitance. Acquisition of higher average current in the ACD mode was attributed to the shorter discharging time compared to the charging time, as well as a higher anode potential caused by discharging the capacitor. Results from circuit analysis and quantitatively calculation were consistent with the experimental observations.

Power electronic converters for microbial fuel cell energy extraction: Effects of inductance, duty ratio, and switching frequency

“…In this study, we investigated the energy extraction with different inductances, duty ratios, and switching frequencies to characterize how these parameters affect MFC energy output performance. The energy harvesting frequency or switching frequency of the power converter ranges from 100 to 5000 Hz, which means that our switching periods (10 msece200 msec) were orders of magnitude shorter than previous studies, which were in the range of hours [8], minutes [12] and seconds [9,10].…”

Anodic concentration loss and impedance characteristics in rotating disk electrode microbial fuel cells

“…EECs consist of common electric elements. The internal resistance in MFCs has been described by many researchers using EIS [34,35]. In this study, the capacitances were calculated by fitting the MFC EIS data.…”

Equivalent circuit modeling of microbial fuel cells using impedance spectroscopy

“…Till date, several EECs have been developed to suit a variety of MFCs [27][28][29][30][31]. A simulation of EEC R(QR)(QR) is reported to determine the internal resistance in upflow MFCs [19,26,32,33]. You et al [34] reported a simulation of EEC R(QR)(CR) to determine the internal resistance of MFCs.…”

“…You et al [34] reported a simulation of EEC R(QR)(CR) to determine the internal resistance of MFCs. The components of internal resistance of MFCs have been the focus of the aforementioned studies in recent years [32][33][34][35]. Equivalent circuit modelling and its experimental validation via EIS is well known in the literature for energy storage devices such as Lithium ion batteries [36,37] and MFCs [38,39].…”