Solid Oxide Electrolyser Cell (SOEC)

Solid Oxide Electrolyser Cells (SOECs) are an emerging electrolyser technology that utilises a solid oxide as the electrolyte. The solid oxide, usually yttria-stabilised zirconia, allows the conduction of oxygen ions between the anode and the cathode. The hydrogen gas is produced at the cathode, and oxygen is produced at the anode as a byproduct. SOECs are characterised by their use of solid oxide electrolytes and high operating temperatures. A schematic of the SOEC technology is presented in Figure X. SOECs are the most efficient water electrolysis technology available today, and they have a high potential for industrial system integration if a methodical waste heat reutilisation approach is adopted.

Being a relatively new technology, the SOEC market is still in its nascent stage, yet it is poised for exponential growth. The current SOEC market size is valued at £93.73m, with an estimated market value of £9.22B. Such a remarkable projection comes on the back of increased government incentives for green hydrogen production, and the high efficiency of SOECs, compared to the AWE and PEMWE technologies. The applications of SOECs are endless, from industrial applications for large-scale hydrogen production and small-scale localised hydrogen production for residential and refuelling stations, to space applications where the hydrogen and the oxygen byproduct may both be utilised.

Despite the huge potential, SOECs are hindered by technological, manufacturing, and logistical challenges that may significantly impact their commercialisation. High temperature operation, while providing high efficiency hydrogen production, severely affects the durability and longevity, often based upon material compatibility. Additionally, the high temperature can currently only be provided by traditional combustion or nuclear integration, severely limiting the greenhouse gas emission reduction potential of SOECs. This requires complex planning for multiple system integration, often navigating through sophisticated control measures to limit energy variability and partial load performance, which in turn increases operational costs in addition to the already high capital costs.