Seca Coal-Based Systems Program

This report summarizes the progress made during the August 1, 2006 - May 31, 2008 award period under Cooperative Agreement DE-FC26-05NT42614 for the U. S. Department of Energy/National Energy Technology Laboratory (USDOE/NETL) entitled 'SECA Coal Based Systems'. The initial overall objective of this program was to design, develop, and demonstrate multi-MW integrated gasification fuel cell (IGFC) power plants with >50% overall efficiency from coal (HHV) to AC power. The focus of the program was to develop low-cost, high performance, modular solid oxide fuel cell (SOFC) technology to support coal gas IGFC power systems. After a detailed GE internal review of the SOFC technology, the program was de-scoped at GE's request. The primary objective of this program was then focused on developing a performance degradation mitigation path for high performing, cost-effective solid oxide fuel cells (SOFCs). There were two initial major objectives in this program. These were: (1) Develop and optimize a design of a >100 MWe integrated gasification fuel cell (IGFC) power plant; (2) Resolve identified barrier issues concerning the long-term economic performance of SOFC. The program focused on designing and cost estimating the IGFC system and resolving technical and economic barrier issues relating to SOFC. In doing so, manufacturing options for SOFC cells were evaluated, options for constructing stacks based upon various cell configurations identified, and key performance characteristics were identified. Key factors affecting SOFC performance degradation for cells in contact with metallic interconnects were be studied and a fundamental understanding of associated mechanisms was developed using a fixed materials set. Experiments and modeling were carried out to identify key processes/steps affecting cell performance degradation under SOFC operating conditions. Interfacial microstructural and elemental changes were characterized, and their relationships to observed degradation identified. Mitigation strategies, including innovative coatings and bond layers, were developed, evaluated and down-selected to improve degradation rates. Focus was on microstructural stabilization and minimization of the ASR contribution from Cr{sub 2}O{sub 3} scale growth and other interactions at electrode/interconnect interfaces evaluated during electrochemical testing and advanced microstructural characterization. Novel long-term and accelerated testing techniques were developed and conducted under standard operating conditions to demonstrate capability to meet targeted degradation rates