M.S. Thesis Presentation by Elizabeth Douglas
Friday, May 9, 2003

(Dr. William Wepfer, advisor)

"Cost Analysis and Balance-of-Plant of a Solid Oxide Fuel Cell /Gas Turbine Combined Cycle"


A baseline solid oxide fuel cell (SOFC) stack was paired with three different gas turbines (GT) (432 kW, 996 kW, 1728 kW) to determine cost effective and efficient combined cycle system designs for use in distributed power applications. The SOFC was sized to match the 432 kW GT so that no additional fuel was required to run the GT at full capacity. A model developed by Haynes was used in this study to calculate output from a tubular SOFC stack paired with a gas turbine bottoming cycle. The SOFC/GT model considers many losses that take place within the system, deducting from the ideal output. All systems were analyzed on a performance basis via parametric studies varying operating pressure, fuel utilization, stoichiometric number, or operating voltage. The performance figures-of-merit were electric and exergetic efficiencies, system exit temperature, required regenerator effectiveness and heat transfer area. Based on the performance study, a favorable set of operating conditions for each GT case was chosen, and cost calculations were performed. Operating curves for each high performance system were developed to aid in the determination of cost effective configurations based upon fuel costs and SOFC capital costs.