Thermo-economic optimization of an indirectly coupled solid oxide fuel cell/gas turbine hybrid power plant

Power generation using gas turbine (GT) power plants operating on the Brayton cycle suffers from low efficiencies, resulting in poor fuel to power conversion. A solid oxide fuel cell (SOFC) is proposed for integration into a 10-MW GT power plant, operating at 30% efficiency, in order to improve system efficiencies and economics. The SOFC system is indirectly coupled to the GT, in order to minimize the disruption to the GT operation. A thermo-economic model is developed to simulate the hybrid power plant and to optimize its performance using the method of Lagrange Multipliers. It predicts an optimized power output of 18.9 MW at 48.5% efficiency, and a breakeven per-unit energy cost of USD 4.54 ¢ kW h−1 for the hybrid system based on futuristic mass generation SOFC costs.

Research highlights
► Present means of power generation are inefficient and not cost effective.
► Combustion can be avoided or reduced using hybrid systems.
► Fuel cells can be coupled with existing power plants to reduce the need for combustion.
► When the coupling is indirect, efficiencies improve from 30% to nearly 50%.
► The cost of producing power drops from 5.46 to 4.54 cents per kWh.