Large Area Solid Oxide Electrolyzer Stack Development for Cost-Effective Hydrogen Production

Abstract

This presentation will provide an overview of the SOEC stack development effort at the Pacific Northwest National Laboratory aiming to construct and operate efficient high temperature electrolyzers for hydrogen and syngas production. Electrode-supported cells with a 300 cm2 active area were fabricated using state of the art materials: Ni-YSZ hydrogen electrode, LSCF oxygen electrode, YSZ electrolyte, and a ceria barrier layer. Stack repeat units consisting of cells, metal frames and interconnects with protective coatings were assembled into several short stacks and tested at 750oC. Initial stack shakedown tests revealed multiple sealing and assembling issues that were timely addressed. Short duration, 200-300 hours parametric tests were then performed to obtain realistic steam utilizations, 50-70%, and hydrogen production rates as a function of operating voltage/current. The electrochemical performance was monitored using dc and ac techniques to determine degradation rates and ohmic and polarization losses.