The most commonly used solid oxide fuel cell (SOFC) anode material is a two phase nickel- and yttria-stabilized zirconia (Ni/YSZ) cermet. During typical fuel cell operation, this material remains a cermet; however, in a commercial SOFC system seal leakage, fuel supply interruption, or other situations may cause the anode to reoxidize. The cyclic reduction and oxidation (redox) of nickel results in large bulk volume changes, which may have a significant effect on the integrity of interfaces within the fuel cell and thus may cause significant performance degradation. Following initial study of the degradation mechanisms and redox kinetics, a number of solutions have been devised. These can be broadly categorized into system solutions and unit cell or materials solutions. The former includes purge gas, other means to produce a reducing gas, cell reversal, and passive solutions such as hydrides, oxygen getters, and steam purging. The latter includes alternative anode materials, microstructural modification of anode functional layers (AFLs), graded porosity, and composition of AFL and redox barrier layers. This paper discusses the pros and cons of each approach and some initial feasibility testing in short-stack repeat units.

Recent progress in the performance of intermediate temperature (500–600°C) protonic ceramic fuel cells (PCFCs) has demonstrated both fuel flexibility and increasing power density that approach commercial application requirements. Under the U.S. DOE ARPA-E REBELS program, the Colorado School of Mines (Mines), in collaboration with Fuel Cell Energy (FCE), is developing durable, kW-scale PCFC stacks and system concepts. Results from cell scale-up efforts are reviewed. Several cells have been tested for over 6,000 hours, and we demonstrate excellent performance and exceptional durability (<1.5%/1,000 hours in most cases) across all fuels without any modifications in the cell composition or architecture. The success of scale-up efforts towards commercially viable, kW-scale cell platforms is given, inclusive of short stack test results. System-level work shows that trade-offs between lower cell power densities (due to lower operating temperature), lower-cost materials, manufacturing processes, and balance-of-stack components exist which can offer competitive advantage for PCFCs in various stationary power applications.

Versa Power Systems (VPS) is a developer of solid oxide fuel cells (SOFCs) for clean power generation. VPS has been working with its development partner FuelCell Energy within the U.S. Department of Energy (DOE) Office of Fossil Energy's Solid State Energy Conversion Alliance (SECA) program to apply SOFC technology in large-scale, multi-megawatt power plant systems that utilize coal in a clean and efficient manner. As a result, new initiatives such as scale-up of the cell and stack are now being actively pursued for these applications.

Experimental results of the performance of a solid oxide fuel cell (SOFC) unit are presented. The unit was designed, manufactured and tested at the VTT Technical Research Centre of Finland. The 10 kW power class SOFC stack and stack module were designed and manufactured by Versa Power Systems (VPS). A successful commissioning test of the unit was conducted in 2010. Long term testing of the unit was started in November 2010. The unit has been operated with natural gas for over 1500 hours supplying electricity to the local grid. The unit has shown robust and uninterrupted performance. Stack DC efficiency of 60% and system net AC efficiency of 43% has been measured during the operation.

Versa Power Systems (VPS) is a developer of solid oxide fuel cells (SOFCs) for clean power generation. VPS has been working with its development partner FuelCell Energy within the U.S. Department of Energy (DOE) Office of Fossil Energy's Solid State Energy Conversion Alliance (SECA) program to apply SOFC technology in large-scale power plant systems. As a result, initiatives such as scale-up of the cell and stack are being actively pursued for these applications.