Performance analysis of a 550MWe solid oxide fuel cell and air turbine hybrid system powered by coal-derived syngas

Highlights: • A MW-level syngas-fueled solid oxide fuel cell/Air Turbine hybrid system. • An intermediate heat exchanger between SOFC and AT. • Pressure and multi-stage SOFC design effects on the overall system efficiency. We here present and analyze a novel conceptual design of 550 MW-level, syngas-fueled intermediate-temperature solid oxide fuel cell (SOFC)/Air Turbine (AT) hybrid system with an oxy-fuel combustion. To decouple the operation of SOFC and AT and allow independent operation of each, an intermediate heat exchanger is implemented between SOFC and AT cycles to transfer only heat from SOFC to AT. To facilitate CO₂ separation and capture, the gas streams from both electrodes are separately operated and pure O₂ is used in the afterburner for combustion. A total of four scenarios has been analyzed to cover the effects of current density, pressure and staged SOFC design. The results show that by elevating the pressure to 10 atm and using two-stage SOFC design, the system can achieve an overall efficiency of 64% at a nominal power output. The work provides important engineering insights in SOFC staged design and operating conditions for the next-generation SOFC/turbine hybrid systems.