Energy Harvesting, Electrode Processes and the Partitioning and Speciation of Solid Phase Iron and Sulfur in Marine Sediments

摘要

Fuel cells that facilitate electrochemical reactions in the marine environment are under development as future long-term power sources for marine instrumentation. This research focused on anode processes and small-scale environmental impacts of fuel cells operated across sediment-water interfaces in laboratory microcosms and at coastal field sites. Sediment, pore water and electrode surface analyses indicated that electricity product ion is coupled to the oxidation of dissolved and solid-phase forms of reduced sulfur supplied from the sediments. Sustainable power densities were observed to increase with time under load by 3-6 times compared to yields from graphite electrodes with no history of passing current. Anode modifications, sediment chemical changes, and the associated enhancement of performance suggest fuel cells promote the development of a localized biogeochemical cycle. Bacteria driving the cycle appear to use elemental sulfur as an energy substrate and may transfer electrons within biofilms.