Achieving high-efficiency hydrogen production using planar solid-oxide electrolysis stacks

•SOEC stacks of 1-cell, 2-cell and 30-cell were tested for electrolysis up to 500 h.•The 1-cell, 2-cell and 30-cell stacks obtained efficiencies of 16.1%, 27.2% and 52.7%.•Multi-cell stack obtained higher system efficiency for electrolysis.

Steam electrolysis in solid oxide electrolysis cells (SOECs) is considered as an effective method to achieve high-efficiency hydrogen production. In the present investigation, samples of 1-cell, 2-cell and 30-cell SOEC stacks were tested under electrolysis of steam to give a practical evaluation of the SOEC system efficiency of hydrogen production. The samples were tested at 800 °C under various operating conditions up to 500 h without significant degradation, and obtained steam conversion rates of 12.4%, 23% and 82.2% for the 1-cell, 2-cell and 30-cell stacks, respectively. System efficiencies of hydrogen production were calculated for the samples based on their real performance. A maximum efficiency value of 52.7% was achieved in the 30-cell stack.