Enhanced power from chambered benthic microbial fuel cells

We describe a new chamber-based benthic microbial fuel cell (BMFC) that incorporates a suspended, high surface area and semi-enclosed anode to improve performance. In Yaquina Bay, OR, two chambered BMFC prototypes generated current continuously for over 200 days. One BMFC was pumped intermittently, which produced power densities more than an order of magnitude greater than those achieved by previous BMFCs with single buried graphite-plate anodes. On average, the continuous power densities with pumping were 233 mW/m(2) (2.3 W/m(3)); peak values were 380 mW/m(2) (3.8 W/m(3)), and performance improved over the time of the deployments. Without pumping, high power densities could similarly be achieved after either BMFC was allowed to rest at open circuit. A third chambered BMFC with a 0.4 m(2) footprint was deployed at a cold seep in Monterey Canyon, CA to test the new design in an environment with natural advection. The power density increased 5-fold (140 mW/m(2) vs 28 mW/m(2)) when low-pressure check valves allowed unidirectional flow through the chamber.