Performance of a Single Chamber Soil Microbial Fuel Cell at Varied External Resistances for Electric Power Generation

Soil is beginning to attract research attention as suitable inoculums for Microbial Fuel Cells (MFCs) designed for remediation and for electricity generation probably due to its high microbial load. However, not much has been done in this aspect beyond laboratory based experiment. This study was aimed at generating electricity from agricultural soil, utilizing the microorganisms present in the soil, and investigating the performance of the soil MFC across varied external loads. The study used the mud watt MFC kit inoculated with mud prepared from topsoil collected from a garden. The electrodes, made from carbon felt material with conducting wires made from graphite, were housed in the same chamber and placed 4cm apart. Voltage drop across seven external resistances of 4670, 2190, 1000, 470, 220, 100, and 47 Ω were measured every 24 hours, with a digital multi-meter, for 40 days. The maximum open circuit voltage from this study was 731 mV, whereas the maximum power density was 65.40 m/Wm2 at a current density of 190.1mA/m2. The optimum performance of the MFC was achieved with the 470Ω at an internal resistance of 484.14 Ω. This study revealed that MFCs constructed from agricultural topsoil are capable of producing electrical power continuously, across different external loads, without addition of any substrate. However, there is need for further studies to keep the MFC output constant at the maximum achievable power.