Solide oxide electrolysis cell (SOEC) technology splits water to produce hydrogen at high temperatures (700-1000°C). The solid oxide electrolyser is the most commonly used technology for high temperature electrolysis (IEA, 2017). Electrolysis is more efficient at higher temperatures, and therefore SOEC is expected to show a higher efficiency than electrolysis technologies using lower operating temperatures (Weeda, 2018). Note that to be considered a sustainable technology both electricity and heat have to come from renewable sources (Weeda, 2018).
An advantage of SOEC is the possibility to co-electrolyse hydrogen and carbon dioxide to produce syngas which can be further processed to methane and other hydrocarbons (De Vita, et al., 2018). A disadvantage of the higher operating temperature is the challenge to find materials that are durable but also cost effective. To be commercialised this issue first needs to be resolved (Pesonen & Alakunnas, 2017).
The H2 output of a SOEC installation has a purity of 94 mol%, which can be purified up to >99% if required (ECN 2018).