chapter  7
36 Pages

Solid Oxide Electrolyzer Cells

ByMichael K.H. Leung, Meng Ni, and Dennis Y.C. Leung

Production of renewable hydrogen with zero net emission of greenhouse gases plays an important role in the development of clean and sustainable hydrogen economy. Renewable hydrogen can be produced by using solar energy directly in thermochemical water splitting to dissociate water into hydrogen and oxygen. However, a recent study has shown that in terms of potential economic benet, thermochemical water splitting is not as attractive as water electrolysis (Graf 2008). Photocatalysis is another potential method for production of renewable hydro gen by direct use of solar radiation to reduce water. For the present

CONTENTS

7.1 Introduction ........................................................................................................................ 179 7.2 Fundamentals of SOEC ..................................................................................................... 180 7.3 Electrolyte ........................................................................................................................... 182

7.3.1 Oxygen Ion-Conducting Electrolyte .................................................................. 182 7.3.1.1 Stabilized Zirconia .................................................................................. 182 7.3.1.2 Doped LaGaO3 ......................................................................................... 186 7.3.1.3 Ceria-Based Oxides ................................................................................. 189 7.3.1.4 Other Oxygen Ion-Conducting Ceramics ........................................... 191

7.3.2 Proton-Conducting Electrolyte ............................................................................ 192 7.3.3 Summary on Electrolyte Materials for SOSE ..................................................... 193

7.4 Cathode ............................................................................................................................... 193 7.5 Anode .................................................................................................................................. 194 7.6 System Designs .................................................................................................................. 195

7.6.1 SOSE Cell and Stack Conguration .................................................................... 195 7.6.2 Waste Heat Utilization .......................................................................................... 196 7.6.3 Electrode Depolarization ...................................................................................... 197

7.7 Mathematical Modeling of SOSE..................................................................................... 199 7.8 Conclusion .......................................................................................................................... 203 References ..................................................................................................................................... 204

development of the technology, the photocatalytic efciency is too low to be economically competitive (Ni et al. 2007a). More research and development are needed to enhance the catalysts and reactor designs.