Abstract
Here we present an approach to predicting sediment microbial fuel cell performance based on environmental conditions. Sediment total organic carbon and water temperature were found to be important determinants in predicting the power output from microbial fuel cells in shallow sediments (<100 m) in San Diego. We extrapolated data from the in situ San Diego experiments to predict MFC performance in shallow sediments in other locations, namely the Gulf of Mexico and the Yellow Sea. Finally, using laboratory data of MFC performance in deep water (~1000 m) sediment samples, we extend our predictions to ocean sediments worldwide. We predict low power output from the deep sea (microwatts) relative to the shallow sediments (milliwatts), and attribute that to a possible lack of electrogenic bacteria in the sediments, lower sediment permeability, or a greater proportion of refractory organic matter reaching the bottom.
Highlights
Microbial fuel cells (MFCs) work by providing electrogenic bacteria, e.g., Geobacter spp., in anaerobic sediments with an electron acceptor that stimulates metabolism of organic matter [1,2,3,4,5,6,7]
The current is limited by the rate of microbial metabolism at the anode
A marine sediment microbial fuel cell is made by placing a non-metallic conductive surface, usually graphite or carbon cloth, on or in sediment under anaerobic conditions
Summary
Microbial fuel cells (MFCs) work by providing electrogenic bacteria, e.g., Geobacter spp., in anaerobic sediments with an electron acceptor (initially a conductive anode) that stimulates metabolism of organic matter [1,2,3,4,5,6,7]. The buried anode is connected via control circuitry to a cathode exposed to oxygen in the overlying water. Bacteria release hydrogen ions into the sediment and transfer electrons extra-cellularly to the anode, which eventually reduces dissolved oxygen at the cathode, forming water. The open circuit voltage is approximately 0.8 V [5,7]. The voltage between electrodes is operationally kept at 0.4 V with a potentiostat. The current is limited by the rate of microbial metabolism at the anode. Work at SPAWAR Systems Center Pacific, a Navy laboratory in San Diego, involves fuel cell design and testing, applications to low power sensors [8,9,10,11,12], and studies of important environmental parameters that affect fuel cell performance
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