Innovative Hybrid Cycle Solid Oxide Fuel Cell-Inverted Gas Turbine with CO2 Separation

Decentralized power generation and cogeneration of heat and power is an attractive way toward a more rational conversion of fossil or biofuel. In small-scale power production fuel cell-gas turbine hybrid cycles are an emerging candidate to reach higher or comparable efficiency than large-scale power plants. The present contribution introduces an innovative concept of hybrid cycle that allows targeting high efficiency together with carbon dioxide separation and maintaining the fuel cell operating under atmospheric condition. The system consists in a planar module of solid oxide fuel cell operating at atmospheric pressure, an oxy-combustion unit, and two separated gas turbine units driven in an inverted Brayton cycle. A thermodynamic optimization approach, based on the system energy integration, is used to analyze several design options. Optimization results demonstrate that the proposed hybrid system enables higher energy conversion efficiency with respect to an equivalent state of the art pressurized hybrid system, whilst avoiding fuel cell pressurization technical problems, and enabling the carbon dioxide separation. The potential of designs achieving 80% First Law efficiency is shown.