The performance of sediment microbial fuel cells (SMFCs) in the field must be evaluated prior to their being relied on as a power source for sensor networks. Currently, the ability to perform such evaluation is limited. The goal of this work was to develop an autonomous, battery-powered, low-cost device (a remote sediment microbial fuel cell tester, or RSMFCT) that can evaluate the field performance of SMFCs charging capacitors in remote areas. The developed RSMFCT allows an SMFC to charge a capacitor between preset charge and discharge potentials and monitors anode and cathode potentials, capacitor potential, and temperature. The RSMFCT was tested at a remote location in the Hot Lake Research Natural Area, near Oroville,WA, USA and used to evaluate the optimum conditions for operating an SMFC. Using the recorded data, the average power and frequency of cycle were determined. We found that SMFCs deployed in Hot Lake operated optimally when charging a 5-F capacitor from 300 mV to 400 mV. Under these conditions, the SMFCs produced an average daily power of 10.28 μW and required an average capacitor charging time of 3.08 hours. We conclude that the RSMFCT is practical for: 1) determining the optimum operation parameters, those that maximize the power output of SMFCs in field operation, and 2) reliably incorporating individual SMFCs as power sources for remote sensor networks by allowing the prediction of their power output and frequency of charge cycles. Several studies have demonstrated that sediment microbial fuel cells (SMFCs) can be used to operate remote sensors in the field.
1-6SMFCs provide cost-effective, long-term power for sensor networks monitoring changes in environmental conditions. SMFCs utilize natural microorganisms and in situ nutrients to convert chemical energy in organic compounds into useful electrical energy.7-9 Accordingly, SMFCs are especially attractive for long-term use because natural organic compounds are continuously renewed by natural processes and inert electrodes and electronic components have a long operation life. The drawback of using SMFCs is that the power generated using SMFCs is relatively low and cannot be used to power most electronic devices continuously. 10,11 The power generated by an SMFC powering sensors varies between 3.4 and 36 mW. 10 However, it is possible to obtain power on the order of hundreds of milliwatts by using large SMFC systems with footprint more than decades of square meters.
12Because of the limitations on SMFC scale-up, directly increasing the size of SMFC electrodes does not result in significant increases in power production. 13,14 On the other hand, the power requirements for remote sensors vary between 10 μW and 85 W, and the sensors most commonly used for environmental monitoring require upwards of 50 mW.10,15 For example, Diamond et al. reported the power required for operating an electrochemical pH electrode is 50 mW. 16 Moreover, a viable deployment strategy for environmental sensor networks requires using wireless communication devices to tran...