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

Abstract

The soil is beginning to receive attention as suitable inoculums for Microbial Fuel Cells (MFCs) designed for remediation and for electricity generation because of its high microbial load. However, not much has been done in this aspect beyond laboratory-based experiments. This study is aimed at generating electricity from agricultural soil, utilizing the microorganisms already present and the soil nutrients as the sole substrates and to investigate the performance of the soil Microbial Fuel Cell (MFC) across varied external loads. The study used the mud watt MFC kit inoculated with mud prepared from topsoil, collected from a garden where crops have been cultivated over the years. The electrodes (anode and cathode, 7cm diameter each), made of carbon felt material with conducting wires made of graphite, were housed in the same chamber and placed 4 cm apart. Voltage drop across seven external resistances 4670 , 2190 , 1000 , 470 , 220 , 100 and 47 , 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 mW/m2 at a current density of 190.1 mAm-2. The optimum performance of the MFC was achieved with the 470 which is an indication that the internal resistance of the soil MFC of this present study is close to 470. This study revealed that MFCs constructed from agricultural topsoil are capable of producing electrical power continuously, across different external loads, without the addition of any substrate.