Up to 399 mV bioelectricity generated by a rice paddy-planted microbial fuel cell assisted with a blue-green algal cathode

Microbial fuel cells are used as an alternative source of energy and for microbial degradation of waste and pollutants. Different types of microbial fuel cells include sediment microbial fuel cells, waste treatment microbial fuel cells, constructed wetland microbial fuel cells and plant microbial fuel cells. Plant microbial fuel cells use plant–microbe relationships for producing bioelectricity. For this cell, the development of efficient, low-cost cathode is a key challenge. Here, a plant microbial fuel cell using algal-assisted cathode was designed. This cell uses rhizodeposits of plants as carbon source in the anode chamber and photosynthesis of algae to generate the oxygen that acts as a terminal electron acceptor in the cathode chamber. Results show that a maximum power density of 29.78 mW/m³ and a current density of 610 mA/m³ were recorded from the polarization curve during the light phase. The maximum voltage recorded was 399 mV in the light phase and 390 mV in the dark phase. This is the first design of a rice paddy-planted microbial fuel cell assisted with a blue-green algal cathode, capable of operating in self-sustainable mode using entirely natural processes without any external input of organics or oxidant.