Supported by the natural potential difference between anoxic sediment and oxic seawater, benthic microbial fuel cells (BMFCs) promise to be ideal power sources for certain low-power marine sensors and communication devices. In this study a chambered BMFC with a 0.25 m(2) footprint was used to power an acoustic modem interfaced with an oceanographic sensor that measures dissolved oxygen and temperature. The experiment was conducted in Yaquina Bay, Oregon over 50 days. Several improvements were made in the BMFC design and power management system based on lessons learned from earlier prototypes. The energy was harvested by a dynamic gain charge pump circuit that maintains a desired point on the BMFC's power curve and stores the energy in a 200 F supercapacitor. The system also used an ultralow power microcontroller and quartz clock to read the oxygen/temperature sensor hourly, store data with a time stamp, and perform daily polarizations. Data records were transmitted to the surface by the acoustic modem every 1-5 days after receiving an acoustic prompt from a surface hydrophone. After jump-starting energy production with supplemental macroalgae placed in the BMFC's anode chamber, the average power density of the BMFC adjusted to 44 mW/m(2) of seafloor area which is better than past demonstrations at this site. The highest power density was 158 mW/m(2), and the useful energy produced and stored was ≥ 1.7 times the energy required to operate the system.

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Wireless marine sensor networks support an assortment of services in industries ranging from national security and defense to communications and environmental stewardship. Expansion of marine sensor networks has been inhibited by the limited availability and high cost of long-term power sources. Benthic Microbial Fuel Cells (BMFCs) are a novel form of energy harvesting for marine environments. Through research conducted in-lab and by academic collaborators, Trophos Energy has developed a series of novel BMFC architectures to improve power generation capability and overall system robustness. When integrated with Trophos' power management electronics, BMFCs offer a robust, long-term power solution for a variety of remote marine applications. The discussions provided in this paper outline the architectural evolution of BMFC technology to date, recent experimental results that will govern future BMFC designs, and the present and future applicability of BMFC systems as power sources for wireless marine sensor networks.