Description: The proposed innovation builds on the successes of the Phase I program by integrating our direct oxidation membrane electrode assembly (MEA) into a monolithic solid oxide fuel cell stack (SOFC) capable of long-term operation on methane or syngas. This innovation is significant because it will contribute to durable, cycle-able simple SOFC systems to meet the needs for NASA and commercial customers. ITN's Phase II strategy addresses the technical hurdles that limit the long-term durability and thermal cycling of state-of-the-art SOFCs operating on methane fuel, including � Matching stack components for coefficient of thermal expansion � Reducing stack mass � Stack sealing � Reducing anode degradation, and � Reducing operating temperatures. With this innovation, we project that the proposed SOFC stack will be capable of operating without degradation for more than the targeted 2500 hours and will operate without power density degradation after 50 start-up and shut-down cycles. By utilizing the direct-oxidation membrane electrode assemblies developed in the phase I program, the thermodynamic efficiencies from fuel source to DC output should exceed 70%. Higher efficiencies translate to lower cooling requirement as obtained by way of conduction through the stack to a radiator exposed to space and/or by anode exhaust flow.

Benefits: NASA needs efficient and reliable methods for both portable and stationary electricity and heat generation, with the greatest possible flexibility. ITN's proposed SOFC stack provides the solution, allowing for SOFC systems capable of generating electricity from a variety of fuels such as syngas, methane, hydrogen or hydrocarbon fuels. Potential NASA customers are the International Space Station or the Human Exploration and Operations Mission Directorate or other long-term missions where such fuels are harvested from the Earth's atmosphere or the atmospheres or surfaces of other planets and used to generate electricity.

The fuel flexibility, high efficiency, scalability, and durability of this SOFC will lend itself to portable and stationary commercial SOFC applications with power outputs ranging from 20 W to 200 kW. An application of particular interest is the distributed energy generation market. Generators for the distributed energy market would range in size from 2 kW for a single household to 200 kW generators for small communities. This SOFC technology is uniquely suited for stationary distributed energy applications because it can operate directly on natural gas, which is primarily composed of methane, with minimal fuel processing and tolerate a wider range of operating conditions than state of the art SOFCs. This is significant for non-NASA commercial customers in the United States because natural gas is widely available to many homes or communities without investment in fuel delivery infrastructure. In addition, these generators could be used with other fuels in many remote applications where grid power is not available.