Testing of Large Format Lower Temperature SOFCs and Stacks with Hydrocarbon Fuels

Redox Power Systems and the University of Maryland Energy Research Center have been developing lower temperature solid oxide fuel cell (SOFC) stacks and systems for a variety of applications.

In this work, results will be presented from single cell and short stack testing using reformate mixtures consisting of CH₄, H₂, CO, CO₂, and steam. Tests utilized large format (approximately 10 cm by 10 cm) cells based on GDC electrolytes with an active area of ~80 cm². Current-voltage characteristics and impedance spectroscopy data were collected at various currents using electronic load and potentiostat/FRA equipment. Additionally, gas compositions in the fuel exhaust stream were determined using gas chromatography.

Initial results at 650 °C showed a single cell power of ~53 W running on hydrogen and ~51 W running on 100% reformate slip (~21% CH₄). Long term test results using a constant applied load of 18 A for a 2 cell short stack showed no evidence of coking even when run on 50% CH₄/50% H₂O for ~50 hours and 97% CH₄/3% H₂O for ~150 hours. Additional long term test results will be presented along with a study on degradation.