Design and performance considerations for benthic microbial fuel cells

Benthic Microbial Fuel Cells (BMFCs) ability to provide long-lasting power is an attractive trait for powering oceanographic equipment requiring long duration deployments. Recent work to scale up BMFC power output with large surface areas (greater than 1 meter squared) has revealed a need to improve power output to make BMFCs viable power sources for a wider breadth of undersea equipment. To improve power output of large surface area BMFCs, experiments were conducted to (1) evaluate different carbon based electrodes; (2) examine alternative materials as current collectors; and (3) determine effects of sediment chemistry and grain size on BMFC power production by testing various mixtures of sand and silt laden sediments. Experiments showed that (1) despite more specific surface area, carbon felt did not generate more power; (2) gold plated copper and titanium current collectors were most capable of reliable connections; and (3) achieving the highest power appears to be a balanced mixture of both fine and coarse sediment. This research provides several important design considerations that demonstrating the importance of the sediment quality at deployment sites for sustaining power output levels capable of powering oceanographic instruments.