(Invited) High-Temperature Electrosynthesis of Hydrogen and Syngas - Technology Status and Development Needs

Abstract

High-temperature solid oxide electrolysis cell (SOEC) technology has been considered and developed for production of hydrogen (from steam) and syngas (from mixtures of steam and carbon dioxide). The SOEC, a solid oxide fuel cell (SOFC) in reverse or electrolysis operating mode, is traditionally derived from the more technologically advanced SOFC. The SOEC uses the same materials and operates in the same temperature range (600˚-800˚C) as the conventional SOFC. The SOEC therefore has the advantages shown by the SOFC such as flexibility in cell and stack designs, multiple options in cell fabrication processes, and choice in operating temperatures. In addition, at the high operating temperature of the SOEC, the electrical energy required for the electrolysis is reduced and the unavoidable Joule heat is used in the splitting process. SOEC technology has made significant progress toward practical applications in the last several years. To date, SOEC single cells, multi-cell stacks and systems have been fabricated/built and operated. However, further improvements are needed for the SOEC in several areas relating to the key drivers (efficiency, reliability and cost) to enable commercialization. This paper provides an overview on the status of SOEC technology, especially zirconia based technology, and discusses R&D needs to move the technology toward practical applications and widespread uses.