Harvesting energy from the marine sediment-water interface

Pairs of platinum mesh or graphite fiber-based electrodes, one embedded in marine sediment (anode), the other in proximal seawater (cathode), have bee n used to harvest low-level power from natural, microbe established, voltag e gradients at marine sediment-seawater interfaces in laboratory aquaria. T he sustained power harvested thus far has been on the order of 0.01 W/m(2) of electrode geometric area but is dependent on electrode design, sediment composition, and temperature. It is proposed that the sediment/anode-seawat er/cathode configuration constitutes a microbial fuel cell in which power r esults from the net oxidation of sediment organic matter by dissolved seawa ter oxygen. Considering typical sediment organic carbon contents, typical f luxes of additional reduced carbon by sedimentation to sea floors < 1000 m deep, and the proven viability of dissolved seawater oxygen as an oxidant f or power generation by seawater batteries, it is calculated that optimized power supplies based on the phenomenon demonstrated here could power oceano graphic instruments deployed for routine long-term monitoring operations in the coastal ocean.