Improved Performance of Soil Microbial Fuel Cell by Adding Earthworms

Soil microbial fuel cells (SMFCs) are expected as an application to produce sustainable energy. Here, we focused on soil ecosystems, specifically the earthworms which are known to improve soil-fertility by degrading fallen leaves or plant litter. The aim of this study was to investigate the effect of earthworm on power generation of the SMFC. The maximum power density and the internal resistance were compared to the SMFC with and without earthworms. The power density increased by about 800% and the internal resistance decreased by about 90%. The soil structure of each SMFC was different and the clear soil aggregate structure was found in the SMFC with earthworms, which had been made with the passage of soil through the earthworm gut. The results indicated that adding earthworms had a significant effect on the SMFC performance, especially the power and soil structure. It is considered that the soil environments were changed biologically and physicochemically by adding earthworms into SMFC and these changes had a positive influence on SMFC. There is no report of hybrid type SMFC combined with earthworm. This is a very novel approach to use earthworms as enhanced power generation through the SMFC.