TECHNOLOGY AREAS: Ground/Sea Vehicles, Materials/Processes, Sensors, Battlespace

ACQUISITION PROGRAM: FORCEnet FNC- GWOT Focused Tactical Persistent Surveillance Enabling Capab.

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), which controls the export and import of defense-related material and services. Offerors must disclose any proposed use of foreign nationals, their country of origin, and what tasks each would accomplish in the statement of work in accordance with section 3.5.b.(7) of the solicitation.

OBJECTIVE: To enable practical use of benthic microbial fuel cells (MFC) to power distributed sensors positioned on or near the river- or sea-floor. Power densities achieved by state-of-the-art, mediatorless MFC require optimization to allow replacement of marine batteries for sensor powering. Given that organic carbon derived from marine/terrestrial detritus is the renewable fuel for the MFC, and that the devices themselves are simple in design - MFCs may be inexpensively and sustainably deployed and operated, from the shallows to the abyssal ocean

DESCRIPTION: ONR has invested in basic and applied research to reveal microorganisms and mechanisms responsible for energy harvesting with benthic microbial fuel cells (BMFC). Operation of these cells has been demonstrated in a number of different marine and riverine environments, including shallow waters (with both sandy or silty mud sediments) and extremely deep, cold seeps (950 m)1. By utilizing supercapacitors and power converters, small but useful amounts of electricity may be obtained2-4.

While it is clear that electricity may be generated through electron transfer from certain microbes to electrodes (principally anodes), and that we have begun to understand the physiological adaptations and mechanisms by which this occurs3-4, theoretical electron yields from organic fuels have been unattainable in practical cell designs. It has been postulated that several factors may contribute to sub-optimal performance of the MFC5-7, such as (1) Internal resistance due to slow proton transfer through the media (water, biofilm) surrounding the electrode, along with interfering inorganic cations (Na+, K+, Ca2+); (2) Poor oxygen reduction kinetics at the cathode, due to scavenging of the O2 by aerobic bacteria at the electrode surface8 and suboptimally reactive cathode materials.

In order to efficiently power devices such as seafloor sensors (acoustic sensor arrays, optical sensors) or recharging stations for autonomous underwater vehicles, new designs that overcome cathodic limitations and internal resistance issues are required. Ideally we will retain the appealing simplicity of the BMFC by utilizing natural microbial populations in ocean sediments and seawater as the source of microbial catalysts, with inexpensive and environmentally-friendly electrode materials - but will exceed the power density (5.85W/m2) maxima reported for a complex tungsten carbide anode with a soil-derived microbial catalyst9.

PHASE I: Devise a laboratory microbial fuel cell design utilizing natural seawater or sediment microbial populations, that consistently provides >2.5W/m2 with a benign small-molecule or complex organic matter fuel.

PHASE II: Devise a laboratory MFC design utilizing natural seawater or sediment microbial populations, that consistently provides >5.8 W/m2, for a period of at least 3 months. Develop and test a prototype benthic MFC in the field, and demonstrate that power densities of >4W/m2 can be achieved and sustained for a period of at least 4 months. Develop, test and integrate a simple power management system to enable economic and optimal use of MFC-generated electricity to power a device for acoustic recording and identification of vessel traffic (to include datalogging)

PHASE III: During this phase, prototype devices will be developed that can record acoustic signals collected from vessels transiting near the device, record the vessel position (within 30m) and transmit this information via a to-be defined communication route. The device will be capable of deployment in a riverine or shallow water (=30m) setting for no less than 6 months, and have a footprint of <1m2 , and will be powered by a BMFC. Proposers will also work with topic authors to identify the most desirable sensors for this phase of research.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: The benthic microbial fuel cell should find utility in the private sector for powering of sea floor instruments used for geotechnical surveying, seismic monitoring, monitoring noise inputs to the ocean (by commercial vessels, oil drilling equipment), for port security (vessel traffic monitoring) and for monitoring movements of threatened and endangered species such as marine mammals.

REFERENCES:
1. Reimers, C.R., et al. (2006) "Microbial Fuel Cell Energy from an Ocean Cold Seep" Geobiology 4: 123-136.

2. Menicucci J., Beyenal H., Marsili E., Angathevar Veluchamy R.R , Demir G. and Lewandowski Z. (2006) "A procedure for determining maximum sustainable power generated by microbial fuel cells". Environmental Science and Technology 40:1062 � 1068.

3. Reguera G, Nevin KP, Nicoll JS, Covalla SF, Woodard TL, Lovley DR (2006) Biofilm and Nanowire Production Leads to Increased Current in Geobacter sulfurreducens Fuel Cells. Appl Environ Microbiol 72 (11):7345-85

4. Gorby YA, et al (2006) "Electrically conductive bacterial nanowires produced by Shewanella oneidensis strain MR-1 and other microorganisms". Proc Nat Acad Sci USA 103:11358�11363

5. Kim, B.H., Chang, I.S. and Gadd, G.M. (2002) "Challenges in Microbial Fuel cell Development and Operation", Applied Microbiology and Biotechnology, 76: 485-494.

6. Lovley DR (2006) "Bug juice: harvesting electricity with microorganisms", Nature Reviews Microbiology 4:497-508.

7. Logan BE, et al., (2006) "Microbial fuel cells: methodology and technology". Environ Sci Technol 40: 5181�519

8. Zhao F, et al. (2006) "Challenges and constraints of using oxygen cathodes in microbial fuel cells". Environ Sci Technol 40:5193�5199

9. Rosenbaum M, Zhao F, Schroder U, and Scholz F (2006) "Interfacing electrocatalysis and biocatalysis with tungsten carbide: a high-performance, noble-metal-free microbial fuel cell", Angew Chem 45:6658�6661

KEYWORDS: microbial fuel cell; sustainable energy; undersea sensor networks; microbial catalyst; energy harvesting; electrode

TPOC: Linda Chrisey
Phone: (703)696-4504
Fax:
Email: [email protected]
2nd TPOC: Martin Kruger
Phone: (703)696-5439
Fax: (703)696-4274
Email: [email protected]