Abstract
In recent years, microbial fuel cells (MFCs), which utilize microorganisms in the soil, have been attracting attention as a new environmental power generation technology. Fuel cells (FCs), which have already been put to practical use in power generators and automobiles, use hydrogen as fuel and generate electric current using hydrogen's electrons. On the other hand, MFCs have the same principle as fuel cells but use organic materials as fuel. Microorganisms break down the organic materials to extract electrons. Various organic materials can be used as fuel, including sugars, carbohydrates, alcohols, agricultural wastewater, and sewage sludge. To expand the application of this technology, it is essential to study the use of freshwater with low conductivity and the optimal conditions of the soil environment. In this study, we focused on the moisture content of the soil to improve the efficiency of microbial fuel cells in freshwater. Soils with different moisture contents were prepared and used in microbial fuel cells to quantitatively evaluate the effect of moisture content on microbial power generation. Under conditions of MFC moisture content up to 82 %, the open-circuit voltage tended to increase with increasing moisture content; when MFC was kept stationary for five days, the highest power generation was observed at 86 % moisture content in the high moisture content region, and power generation tended to decrease as moisture content increased to 91 %. When MFCs with similar moisture content were mixed once a day, the amount of electricity generated grew higher when the moisture content was 91 % than when the moisture content was 86 %.
