Dr. Kim, Sun-dong and his research team from the Hydrogen Convergence Materials Laboratory of the Korea Institute of Energy Research (KIER), along with President Yi Chang-keun, have developed a solid oxide electrolysis cell (SOEC) and a stack to produce clean hydrogen through steam electrolysis. The developed stack shows higher efficiency in hydrogen production at lower temperatures compared to current SOEC stacks. 

SOEC has been recognized as the advanced electrolysis method that consumes less electrical energy. The usual practice for steam electrolysis involves operating at a high temperature of 850℃. SOEC has proven to be a highly effective method of generating significant amounts of hydrogen with increased efficiency.

So far, SOEC is designed directly from solid oxide fuel cell (SOFC). The KIER SOEC stack is designed specifically for SOEC and is not borrowed from SOFC design. The main advantage of the KIER SOEC design is its suitability for steam electrolysis. 

Researchers focused on the difference in gas flow configuration between hydrogen, the fuel for SOFC, and steam, the fuel for SOEC. Steam has a larger volume and lower viscosity than hydrogen, which can lead to flow hindrance and irregularities on the surface of cell catalysts, resulting in low efficiency in hydrogen production. Therefore, they designed a solid oxide cell optimized for the steam flow configuration to ensure consistent and regular flow, which is essential for excellent efficiency in hydrogen production. 

The SOEC stack is equipped with electrode-supported cells, ideal for large-scale hydrogen production, rather than electrolyte-supported cells commonly used in other countries. As a result, the stack performs at lower temperatures between 650°C and 750°C, which is 100°C to 200°C lower than current temperatures. This reduces electricity consumption and enhances hydrogen production. Once the stack operates at 750℃, one cell achieves about 100% electrical efficiency based on lower heating value (LHV) and produces 32 liters of hydrogen per hour. Usually, a stack with 30 cells produces 1,000 liters of hydrogen per hour. 

Besides the SOEC cells and stacks developed by the KIER, other parts of the stack, including bipolar plates and sealing, are designed and made exclusively from domestic materials.

Dr. Kim, Sun-dong stated that this technological achievement is a significant milestone for SOEC. He added, "I will do my best to make the country a center for low-cost and large-scale green hydrogen production by improving the performance and durability of the SOEC I have developed.”