Direct JP-8 Conversion Using a Liquid Tin Anode Solid Oxide Fuel Cell (LTA-SOFC) for Military Applications

Abstract

A liquid tin anode solid oxide fuel cell (LTA-SOFC) is actively being developed for direct utilization of JP-8 logistic fuel. Since its invention in 1998, the LTA-SOFC has demonstrated the ability to operate on various carbonaceous fuels including hydrocarbons, alcohols, carbon, biomass, and coal without fuel reforming or reprocessing to remove known impurities such as sulfur. Natural gas fueled 1kW stand alone prototypes for distributed power generation and have previously demonstrated over 2000h of continuous operation. The aim is to develop simple and reliable portable power that operates directly off JP-8 and other carbonaceous fuels. The current program focuses on improvement of power density and cell manufacturability. Cell geometry was modified from the previous design to optimize power density while minimizing cell weight and volume. The cell construction is a liquid tin anode housed in a porous separator, an 8mol% yttria stabilized electrolyte, and a strontium doped lanthanum magnate cathode. Experimentation was conducted on single cells at 1000°C. The JP-8 fuel used for experimentation contained a sulfur content of 1400ppm. The direct JP-8 conversion in a LTA-SOFC demonstrated up to 41% efficiency. The LTA-SOFC was also capable of maintaining greater than 30% efficiency at 70% of maximum power output at a JP-8 flow rate of 10μlmin−1. Continuous operation with direct conversion of JP-8 was sustained for over 100h with efficiencies of 41–17%. A maximum power density of 120mWcm−2 was sustainable on a JP-8 flow rate of 50μlmin−1. The current Gen 3.1 cell design can sustain a maximum power of 120mWcm−2 by direct conversion of JP-8 without fuel processing, reforming, or sulfur removal. Efficiencies of up to 41% were sustained for a minimum of 1h, with continuous operation on JP-8 for over 100h. Further performance improvements are anticipated, thereby facilitating LTA-SOFCs use for military and civilian applications that demand flexible fuel.