Power generation in a plant-microbial fuel cell assembly with graphite and stainless steel electrodes growing Vigna Radiata

Abstract

Plant-microbial fuel cells (PMFCs) are an interesting renewable energy technology that has the potential to generate clean electricity without competing with agriculture for land space. In this study, the electricity generation potential of mung beans (Vigna radiata) in a PMFC set-up with different electrode materials was explored. Three types of set-ups were prepared with five replicates each: PMFCs with stainless steel electrodes, PMFCs with graphite electrodes, and control pots without electrodes. This experimental set-up allowed for the evaluation of the better electrode material, and whether the PMFC environment harms or benefits the plants. The voltage gathered suggests that the potential difference generated in the PMFCs with differing types of electrodes were statistically the same (α = 0.05). The same can be said for power and power density, although the system with stainless steel electrodes generated more power towards the end of the experiment. It was also evident that PMFCs with stainless steel electrodes experienced prolonged time lags due to the reduced biocompatibility of stainless steel. Polarization studies showed that a single PMFC is capable of generating power densities of 0.35 mW/m2 and 0.12 mW/m2 for stainless steel and graphite systems, respectively. The increased power density of PMFCs with stainless steel indicate the lowering of internal resistance brought by the stainless steel. Plants in the PMFCs set-ups were seen to grow faster, taller, and have higher pod output than those in the control set-up. These results indicate that the PMFC technology can be implemented in agricultural land for the continuous generation of passive electricity while growing food crops, eliminating the competition between energy generation and agriculture.