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Seafloor Lab

The Project

Introduction
"An immense energy reserve sits on the seafloor," beings the ground-breaking paper published in Nature Biotechnology detailing the grand experiment that reveals an aspect of the sea that few people besides a handful of distinguished academics and the fine minds at the U.S. Navy could have predicted. What they discovered was that the thick bed of organic carbon found on the bottom of the seafloor could be oxidized by microorganisms. This in itself would not be amazing but for the fact that the natural conditions created by the organic carbon and the sea lends itself for energy production.

What kind of research is the project involved in? W
This undertaking, which is more like a project than an actual scientific laboratory, involves the collaboration of many of North America's most distinguished researchers in fields ranging from oceanography to microbiology. This project is devoted to the categorization of the microbes that inhabit the area and aid in electricity production (with help from the Geobacter lab), the testing of electrical output for the novel device, and the improvement of the overall efficiency.

The collaborators created two test sites: one at a swamp near Tuckerton, New Jersey, and another at the Yaquina Bay Estuary in Newport, Oregon. At each site, they deployed two rather large graphite discs with holes punched through them joined by silver epoxy (a substance made out of three-unit rings with an oxygen). At each site they put a closed circuit to test the amount of electricity generated and an open circuit as a control. The Newport deployment was used to measure the ability of the fuel cell to sustain a steady current at a constant voltage of 0.27V, and the Tuckerton site was used to measure power output with fluctuating current and voltage. The fuel cells maintained remarkable stability despite some environmental fluctuations you would expect underwater.

What kind of bacteria do they use?
On the active fuel cells (not the controls), the most abundant bacteria class were the delta Proteobacteria subclass, which includes the Geobacter microorganisms. Though the bacteria found were not all the same bacteria that are being studied by the Geobacter Project, they are very closely related, so inferences can be made between the species. Since that group of bacteria occupies the majority, scientists have thought it wise to focus their efforts on learning as much as they can about them.

How does their fuel cell work?
Dr. Leonard Tender and the other scientists working on this project have contructed a fuel cell that fits snugly into the natural framework of nature. The anode goes into the bottom of the organic carbon mass where the bacteria oxidize the organic carbon and other compounds such as acetate, putting electrons into the electrode. As you go up, there is a linear gradient of organic stuff, so at the cathode there is comparatively less organic sediment. This natural difference takes away the need for a two-compartment cell and a semi-permeable membrane as the structure for the MFC. The huge advantage of this setup is its self-sustainability with relatively small human maintenance needs. This is important for long-term powering of oceanographic equipment.

The Future

What are the possible applications?
This project, besides in a way being a practical application in and of itself, has great potential in providing energy to oceanographic tools. For example, integrated conductivity, depth and temperature sensors that rely on a small amount of power but for a long period of time could definately use an underwater battery that would be self-sustaining. It is unlikely for now that something like this could act as a power source for something more lucrative and energy-intensive such as powering a whole city because of the limited power output.

What else are they trying to discover?
One of the problems often encountered with placing objects for a long time in marine environments is that they get fouled or clogged. Fouling does not appear to be a problem in long-term steady energy production, but researchers intend to study the effects of oxidative current on the bacteria that colonize the anode (like certain Geobacter) to develope better antifouling strategies to improve the MFC's efficiency.

How will this impact the environment?
This talk about inserting things into marine environments inevitably raises the question of how it will affect the ecosystem in the long term (i.e. will it make anything go extinct?). It is not entirely certain what the answer to that question is, but the Newport deployment began in Jan. 2001 and ended Jan. 2002. The Tuckerton one began at the same time, but it only lasted for six months. This may not be considered a sifficiently long period of time to give a sigh of relief, but for now it seems as if the only effect of the MFC is a novel way of powering undersea equipment.
     
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