Hydrogen Production Performance of a 10-Cell Planar Solid-Oxide Electrolysis Stack

An experimental study is under way to assess the performance of solid-oxide cells operating in the steam electrolysis mode for hydrogen production over a temperature range of $800-900°C$⁠. Results presented in this paper were obtained from a ten-cell planar electrolysis stack, with an active area of $64cm2$ per cell. The electrolysis cells are electrolyte supported, with scandia-stabilized zirconia electrolytes (⁠$∼140μm$ thick), nickel-cermet steam/hydrogen electrodes, and manganite air-side electrodes. The metallic interconnect plates are fabricated from ferritic stainless steel. The experiments were performed over a range of steam inlet mole fractions (0.1–0.6), gas flow rates $(1000-4000sccm)$⁠, and current densities $(0-0.38A∕cm2)$⁠. Steam consumption rates associated with electrolysis were measured directly using inlet and outlet dewpoint instrumentation. Cell operating potentials and cell current were varied using a programmable power supply. Hydrogen production rates up to $100Nl∕h$ were demonstrated. Values of area-specific resistance and stack internal temperatures are presented as a function of current density. Stack performance is shown to be dependent on inlet steam flow rate.