Techno-Economic Optimization of SOC Design and Operating Conditions in a Solid Oxide Fuel Cell-Gas Turbine Hybrid System

Abstract

In a circular economy, highly efficient energy conversion systems are paramount to maximize resource utilization and minimize waste production, including carbon dioxide emissions. Solid oxide fuel cell-gas turbine hybrid systems, which can reach efficiencies of greater than 75%-LHV, have demonstrated to be a promising technology on the way to cleaner power generation. During the energy transition period, solid oxide fuel cell-gas turbine hybrid systems are likely to be operated on natural gas, however, their scalability allows these systems to reach very high efficiencies even at small scales, enabling the use of distributed resources such as biogas. In this presentation the authors will discuss key performance and economic metrics of small-scale (10 MW) advanced solid oxide fuel cell-gas turbine hybrid systems and their relation to cell design and system design elements. Current challenges in solid oxide fuel cell development include thermal cell management and production cost. This presentation presents findings of how cell design parameters influence thermal gradients and specific solid oxide cell costs on a $/kW-basis under hybrid system operating conditions. Moreover, specific cell components are identified, and effects will be discussed that can synergistically reduce thermal stress and specific cell cost at the same time. Informed by this analysis, the optimized cell design is integrated into a solid oxide fuel cell-gas turbine hybrid system in order to provide a comprehensive analysis of system operating conditions under consideration of thermal cell gradients, and new insights into economics and levelized cost of electricity are provided. The presentation will discuss the impact of fuel utilization, operating voltage, and operating pressure upon the heat integration, system’s operating window, and power output. A discussion of economic parameters will highlight cost driving factors to inform research on the next generation of solid oxide cells.