Oceanic Redox Powers Monitoring Instruments

Microbial fuel cells that run on ocean redox chemistry will never create enough power to solve the global energy crisis, but Oregon State University researchers report a novel chambered design with the potential to replace batteries currently used in oceanographic monitoring equipment. In other benthic fuel-cell prototypes, the anode is buried in sediment, where microorganisms oxidize organic matter to produce sulfide and methane. The electrons liberated in the process pass through a circuit and combine with hydrogen ions and dissolved oxygen at the cathode, generating water and electricity. But the diffusion of sulfide and methane in these systems is too slow. Mark E. Nielsen, Clare E. Reimers, and Hilmar A. Stecher III at Oregon State now have field-tested a design in which the anode is enclosed in a chamber above the sediment, which promotes better circulation of sulfide and methane (Environ. Sci. Technol., DOI: 10.1021/es071740b). When positioned near a deep-sea vent that aids circulation, the fuel cell produced 60 mW of sustained power. This output is a fivefold increase relative to other systems and high enough to run various oceanographic sensors continuously.