Man-Portable, Direct-Fuel Capable, Tubular Solid Oxide Fuel Cell

A lightweight and man-portable 300W tubular solid oxide fuel cell is being developed that can operate directly from liquid fuels without the need for separate fuel processing. A novel freeze-casting approach is being used to produce the anode-supported cells with an integrated catalyst that prevents sulfur and carbon in the fuel from degrading the electrical performance over time. Solid oxide fuel cells have long suffered from degradation due to impurities in the fuel and complexities associated with dissimilar materials and high operating temperatures.  A unique microstructure for a tubular anode-supported SOFC is being developed using this novel freeze-casting technique, with the promise of increasing the cell triple phase boundary area and allowing for very high surface area for the anode catalyst.  Currently, the freeze-cast tube technology (the heart of the system) has been scaled from a small diameter, many-tube bundle, developed during the initial Phase II project, to a larger tube diameter/length that requires significantly less tubes, and associated sealing and integration complexity. During the initial Phase II testing, the major technical limitation stemmed from the anode current collection with the small tube diameter, and this was found to be the major contributing factor to the lower power density from the prototype. Currently, the team is working to complete the fabrication of the improved 300W bundle, as well as the heat exchanger and associated electronics package under the current contract. Thus far in the current contract, the laboratory testing results at GT indicate good performance of the scaled tubes, and work is progressing on specialized catalysts for the transition to liquid high sulfur fuel testing, which has recently demonstrated promising operation >50 hours duration.  The 300W bundle design with very targeted efforts at lightweighting, has progressed to the initial fabrication phase, and by the end of the current project, we will have a breadboard bundle prototype and limited control systems demonstrated.   By the end of our current contract, we anticipate the 300W size generator bundle and heat exchanger to be fabricated and demonstrated at a benchtop level, and the man-portable, ruggedized, exterior case prototyping to be at the late design stage. In the proposed Sequential Phase 2 STTR project, the project team intends to advance the complete generator design and system integration, to include full packaging, automatic controls and user interface, and delivery of an engineering and manufacturing development unit to the Army.