| The necessity for the highly efficient production of hydrogen increased as the hydrogen economy emerged as a promising answer for tomorrow's energy woes. The generation of hydrogen through electrolysis possessed several advantages, such as high efficiency, low pollutant emissions and flexible fueling strategies. The main goal of this research was to increase the efficiency of hydrogen production by operating the Solid Oxide Electrolysis Cell (SOEC) at an optimum combination of operating conditions. Theoretically, the efficiency of a solid oxide electrolysis cell improved with increased temperature as a result of reduction in the Gibbs free energy change. This study researched and proposed an alternative way to achieve the high temperatures required for the electrolysis process.;The investigation consisted of three main features: conceptualization, modeling/simulation and validation. The conceptualization phase explained the concept of the recuperative solid oxide electrolysis cell that utilized thermal energy from exhaust gases and solar energy. In the second stage, a mathematical model was developed that described the operation of the recuperative solid oxide electrolysis system. Various operating parameters, such as voltage, steam utilization, area specific resistance, the size of the heat exchangers, and number of cells, among others, were used to model the system. The formulated model was then simulated, using a software package developed for this purpose. The final stage was to obtain results from an experimental set up to validate the model. In the experimental set up, the SOEC cell was subjected to a range of steam utilization and operating voltage to estimate the temperature response and hydrogen production.;The main objective of this work was to identify the optimum operating conditions of the recuperative solid oxide electrolysis system through parametric modeling. This modeling includes investigating whether the operation of the electrolysis cells at an operating voltage above the thermoneutral voltage was beneficial in the long run. The profit obtained from the production of hydrogen over the lifetime of operation of the solid oxide electrolysis cell was calculated for each set of operating conditions. It was found that the exit temperature of the gas streams depended on the operating voltage and steam utilization, simultaneously. It was also found that operating the recuperative electrolysis cell above thermoneutral voltage at around 1.4V-1.5V to be profitable in terms of hydrogen production. |
