Aerobic Miniature Microbial Fuel Cells

摘要

Distributed autonomous sensor (DAS) networks will require sustainable energy-scavenging power sources for persistent surveillance applications. Ideally, these power sources will scale with the sensor size (micro/nanoelectromechanical) to enable covert deployment and a small power budget. Based on their ability to sustain power production for years while scavenging energy from a variety of environments and nutrients, microbial fuel cells (MFCs) are a viable solution to power water-borne DAS networks. However, to date, nearly all MFCs are large and bulky (100 cu cm to cu m), making them significantly larger than many sensors and communication packages. Researchers in the NRL Chemistry and Oceanography Divisions have recently developed the first high power density miniature MFC (mini-MFC). The mini-MFC has a 2.0 sq cm cross-section and a 1.2 cu cm volume, making it orders of magnitude smaller than traditional MFCs. Additionally, the mini-MFC is designed to maximize current collection and proton diffusion to the cathode, enabling unprecedented power per area (3 W/sq m) and volume (500 W/cu m) when using graphite felt electrodes and Shewanella oneidensis cultured under micro-aerophilic conditions. These power densities are sustained when S. oneidensis biofilms on the anode are used with acellular media. Previous to this work, mixed consortia of bacteria with the ability to utilize electron donors efficiently needed to be used to produce current densities above 50 W/cu m. The mini-MFC design and size create a unique device that enhances power production per volume when compared to any other MFC design in the literature. These results are an indication that further size reductions may further increase power density and enable microbial energy scavengers to power DAS networks for Navy-relevant applications in the littoral water column.