Hydrogen production through steam electrolysis: Control strategies for a cathode-supported intermediate temperature solid oxide electrolysis cell

Hydrogen production via steam electrolysis may involve less electrical energy consumption than conventional low temperature water electrolysis, reflecting the favourable thermodynamics and kinetics at elevated temperatures. The present paper reports on the development of a one-dimensional dynamic model of a cathode-supported planar intermediate temperature solid oxide electrolysis cell (SOEC) stack with air flow introduced through the cells. The model, which consists of an electrochemical model, two mass balances, and four energy balances, is here employed to study the prospect of the stack temperature control through the variation of the air flow rate. The simulations found that the increase in the air flow rate provides enhanced cooling and heating during exothermic and endothermic operations, respectively. The stack behaviour has suggested that such a convective heat transfer between the cell components and air flow would allow the control of stack temperature. However, only a small dependence of the temperature on the air flow rate was observed for a stack driven at conditions near thermoneutral operation, indicating that this operating mode should be avoided from a control perspective. (C) 2008 Elsevier B.V. All rights reserved.