Benthic microbial fuel cell systems for marine applications

Energy sources that may be converted to electric power are elusive at the seafloor. This communication describes the design of a compact benthic microbial fuel cell (BMFC) and a power management platform (PMP) that have been used to recharge lithium-ion batteries with energy harvested in situ from biomass enclosed in the BMFC's anode chamber. The primary power produced was typically between 5 and 50 mW with 42% of the energy transferred to battery storage. The batteries in turn were used to sustain environmental sensors and acoustic communication devices during three experiments in contrasting marine locations. The programmable PMP permitted control of sensor duty cycles and monitoring of BMFC performance. One of the experiments occurred at an ocean depth of 580 m for 1,045 days. It suggested a need for longer lasting biomass supplies to sustain elevated power levels beyond 2–3 years. Based on the lessons learned from these experiments, we conclude that BMFC systems are now sufficiently mature to be applied within marine observing networks. They represent an alternative power source that may be integrated readily with many kinds of innovative sensors.