A High-Efficiency Solid Oxide Fuel Cell Hybrid Power System Using the Mercury 50 Advanced Turbine Systems Gas Turbine

The conceptual design of a 20 MWe-class hybrid power generating system that integrates a Siemens Westinghouse pressurized solid oxide fuel cell generator with a Mercury 50 gas turbine is discussed. The Mercury 50 was designed and developed by Caterpillar/Solar Turbines during the U.S. Department of Energy (DOE) Advanced Turbine Systems (ATS) program, and the hybrid system design concept was evaluated during a recently completed project that was part of the DOE high efficiency fossil power plant (HEFPP) program. While achieving a high power system efficiency by the hybrid cycle approach was important, the focus of the design study was to select the solid oxide fuel cell (SOFC) generator capacity such that the low specific cost of the ATS gas turbine and the high efficiency of the more expensive pressurized solid oxide fuel cell (PSOFC) generator would combine optimally to produce an attractively low cost of electricity (COE) for the overall power system. The system cycle and physical characteristics are described; power, efficiency, and emissions estimates are presented; and estimates of system cost and COE are provided. In addition, two bottoming cycle options (steam turbine and ammonia turbine) are described, and performance and cost projections for each are reviewed.