Dynamic analysis on a hydrogen production system based on a 20kW solid oxide electrolysis stack

Solid oxide electrolysis cell (SOEC) is a promising technology to produce cheap green hydrogen by renewable electricity owing to its high efficiency and low material price. Considering the fluctuation of renewable electricity, the dynamic performance of SOEC system is important in application. In this work, a dynamic model for the hydrogen production system based on a 20kW SOEC stack is developed and the model is validated by experimental data reported in literature. The dynamic response of this system is studied by inputting a ramp change of current density and the change of electrolysis voltage, stack power, stack temperature, system power and hydrogen production efficiency are analyzed. Results show that the electrolysis voltage, stack power and system power can rapidly respond to the fluctuation of current density, but the change of stack temperature is very small (Max. 4.6°C) due to the great thermal capacity of SOEC stack, which implies that the SOEC stack can maintain its operating temperature at a small range of power fluctuation. The change of system efficiency is mainly dependent on the electrolysis efficiency of SOEC stack.