Hybrid Systems Based on Solid Oxide Fuel Cells

MARIO L. FERRARI is Associate Professor in the Dipartimento di Ingeneria Meccanica, Energetica, Gestionale ed dei Trasporti (DIME) of the University of Genova, Italy. USMAN M. DAMO is at the School of Mechanical, Aerospace and Civil Engineering, The University of Manchester, UK, as a Research Associate. ALI TURAN is a Professor and chair holder in the thermodynamics of power generation and propulsion at the University of Manchester, UK. DAVID SÁNCHEZ is currently a Professor in Energy Systems and Turbomachinery in the Department of Energy Engineering at the University of Seville, Spain.

• Preface xiAcknowledgements xv1 Introduction 11.1 World Population Growth, Energy Demand and its Future 11.2 World Energy Future 31.3 Introduction to Fuel Cells and Associated Terms 61.3.1 Background for Fuel Cells and Thermodynamic Principles 61.3.2 Solid Oxide Fuel Cells (SOFCs) 111.3.3 Fuel Cell Reactions 151.3.4 Fuel Cell Performance 151.3.5 Pressure and Concentration Effects 181.3.6 Irreversibilities in Fuel Cells 191.3.7 Fuel Cell Applications 231.4 Gas Turbines 241.4.1 Background of Gas Turbines 241.5 Coupling of Microturbines with Fuel Cells to Obtain ‘Hybrid Systems’ 251.5.1 Active Hybrid Systems Research Groups 291.6 Conclusions 29References 292 SOFC Technology 332.1 Basic Aspects of Solid Oxide Fuel Cells 332.2 SOFC Types 352.2.1 High-temperature SOFCs 352.2.2 Intermediate/Low-temperature SOFCs 352.3 Materials for SOFCs 362.4 Different SOFC Geometries 382.4.1 Tubular SOFCs 392.4.2 Planar SOFCs 412.5 SOFC Stacks 432.6 Effect of Pressurization for SOFCs 442.7 Fuel Processing for SOFCs 452.7.1 Processing for Gas and Liquid Fuels 462.7.2 Processing for Solid Fuels 482.8 SOFC Applications in Hybrid Systems 492.8.1 Atmospheric SOFC Hybrid Systems 502.8.2 Pressurized SOFC Hybrid Systems 512.9 Aspects Related to SOFC Reliability, Degradation and Costs 522.10 Conclusions 542.11 Questions 54References 553 Micro Gas Turbine Technology 593.1 Fundamentals of the Brayton Cycle 593.1.1 The Simple Cycle 593.1.2 The Simple Recuperative Cycle 683.1.3 The Intercooled and Reheat Brayton Cycles 743.1.4 The Intercooled and Reheat, Recuperative Brayton Cycle 793.1.5 Cycle Layouts used by Contemporary Micro Gas Turbines 843.2 Turbomachinery 853.2.1 General Considerations on the Selection of Turbomachinery for Micro Gas Turbines 853.2.2 Fundamentals of Radial Compressor Design and Performance 893.2.3 Some Notes on Compressor Surge 1013.2.4 Fundamentals of Radial Turbine Design and Performance 1053.2.5 Scaling of Radial Turbomachinery 1133.3 Recuperative Heat Exchanger 1153.4 Bearings 1243.5 Conclusions: Commercial Status and Areas of Research 1313.6 Questions and Exercises 134References 1354 SOFC/mGT Coupling 1414.1 Basic Aspects of SOFC Hybridization 1414.2 SOFC Coupling with Traditional Power Plants 1434.2.1 Coupling with Steam Power Plants 1434.2.2 Coupling with Gas Turbines 1444.2.3 Coupling with Combined Cycle-based Plants 1464.3 Beneficial Attributes Related to SOFC/mGT Coupling 1474.4 Constraints Related to SOFC/mGT Coupling 1504.4.1 Turbine System Constraints 1524.4.2 SOFC System Constraints 1564.4.3 Control System Constraints 1584.5 Design and Off-design Aspects 1594.5.1 Design Aspects 1594.5.2 Off-design Aspects 1614.6 Issues Related to Dynamic Aspects 1634.7 Main Prototypes Developed for SOFC Hybrid Systems 1664.7.1 Prototype by Siemens-Westinghouse 1674.7.2 Prototype by Mitsubishi Heavy Industries 1694.7.3 Prototype by Rolls-Royce Fuel Cell Systems 1704.8 Conclusions 1714.9 Questions and Exercises 173References 1745 Computational Models for Hybrid Systems 1835.1 Introduction 1835.2 Steady-state Models for Hybrid Systems 1855.3 Computational Models for Hybrid Systems: Modelling Steps 1865.3.1 Computational Models for Hybrid Systems at the Component Level 1905.3.2 Prediction of Performance of Gas Turbines 1915.3.3 Off-design Operation of the Single-shaft Gas Turbine 1925.3.4 Off-design Calculation with ‘Complex’ Layout Turbines 1965.4 System Modelling 2005.4.1 Reformer 2015.4.2 SOFC Module 2055.4.3 Overpotentials 2075.4.4 Fuel and Air Supply Calculations 2085.4.5 Combustor 2095.4.6 Turbine 2105.5 Compressor 2115.5.1 Recuperator 2115.6 Results and Discussion 2125.7 Dynamic Models 2135.8 Model Validation 2165.9 Conclusion 2175.10 Questions and Exercises 218References 2186 Experimental Emulation Facilities 2256.1 Experimental Emulation Facilities 2256.2 Reduced-scale Test Facilities 2266.2.1 Anodic Recirculation Test Rig 2276.2.2 Cathodic Loop Test Rig 2296.3 Actual-scale Test Facilities 2326.3.1 Low-temperature Rigs 2336.3.2 High-temperature Rigs 2366.4 Conclusions 2476.5 Questions and Exercises 247References 2497 Problems and Solutions for Future Hybrid Systems 2557.1 The Future of Micro Power Generation Systems 2567.2 The Future of Hybrid Systems: Hydrogen as an Energy Carrier 2587.2.1 Hydro-methane and Hydrogen-rich Fuel Mixtures 2597.3 Future Hybrid Systems: Design, Optimization and Sizing 2607.3.1 Hybrid Systems Sizing Techniques 2617.3.2 Hybrid System Sizing Simulation Tools 2627.4 Cost Analysis of Hybrid Systems for Power Generation Applications 2647.5 Performance Degradation Problems in Solid Oxide Fuel Cells 2687.6 Turbomachinery Problems 2697.7 Dynamic and Control System Aspects 2717.8 CO2 Separation Technologies for SOFC Hybrid Plants 2727.9 Coal and Biofuel for Hybrid Systems 2737.10 Conclusions 275References 275Glossary 285Index 307

In summary, this book provides comprehensive information and guidelines on the design and modeling of hybrid SOFC and gas turbine systems. Researchers, scientists, and engineers who are interested in developing such a hybrid system or carrying out new research in the area of integrated fuel cell systems will definitely get valuable information from this book. This book could also be effectively used as a reference book in some graduate level courses in energy conversion and fuel cell technology. There are also very interesting questions and exercises found at the end of the chapters, which could be given as assignments to students. In conclusion, I recommend this book as a unique source of information on the hybrid SOFC and gas turbine systems. -Dr. Can Ozgur Colpan, Dokuz Eylül University, Izmir, Turkey