Lifespan evaluation of two 30-cell electrolyte-supported stacks for hydrogen production by high temperature electrolysis

Abstract

The levelized cost of electrochemical hydrogen remains significantly affected by stack replacement frequency, and therefore stack durability. Consequently, demonstrating relevant lifespans is paramount towards supporting the accelerating industrialization of solid oxide technology.Thus, two 30-cell electrolyte-supported stacks were tested in thermoneutral conditions, −0.52 A cm−2 and 70% steam conversion. The first stack comprised a variety of cells and over the 4.5 kh test sequence yielded a degradation rate of +22 mΩ cm2 kh−1, or +4.5 K kh−1. The second stack only included the best cell variant, and degraded at a much lower rate of +12 mΩ cm2 kh−1, or 2.5 K kh−1. The test lasted 9.5 kh, a record for full stacks operated in electrolysis mode.The present report details the testing equipment, the experimental conditions and procedures, and compares the performances and degradation rates recorded. In addition, special attention is given to the feed water quality over time.