Fuel cell-gas turbine hybrid system design part I: Steady state performance

The hybridization of gas turbine technology with high temperature fuel cells represents an ultra-high efficiency, ultra-low emission, fuel flexible power generation platform. The performance of past prototypes has been limited by marginal compatibility of the two primary sub-systems. This paper addresses the challenge of selecting compatible hardware by presenting a simple and robust method for bespoke hybrid system design and off-the-shelf component integration. This is the first application of detailed, spatially resolved, physical models capable of resolving off-design performance to the integration analysis of FC-GT hybrids. Static maps are produced for both turbine and fuel cell sub-systems that readily evaluate the compatibility and hybrid performance. Molten carbonate and solid oxide fuel cells are considered for hybridization with recuperated micro-turbines and larger axial flow gas turbine systems. Current state-of-the-art molten carbonate technology is shown to pair well with present micro-turbine technology in an FC bottoming cycle design achieving 74.4% LHV efficiency. Solid oxide technology demonstrates remarkable potential for integration with larger scale axial turbo-machinery to achieve greater than 75% LHV efficiency. This performance map technique closely matches results from detailed integrated hybrid system analyses, and enables quick determination of performance requirements for balance of plant design and optimization.