TABLE OF CONTENTS
1. TECHNOLOGY OVERVIEW1-1
1.1 INTRODUCTION
1.2 UNIT CELLS 1-2
1.2.1 Basic Structure 1-2
1.2.2 Critical Functions of Cell Components
1.3 FUEL CELL STACKING1-4
1.3.1 Planar-Bipolar Stacking 1-4
1.3.2 Stacks with Tubular Cells 1-5
1.4 FUEL CELL SYSTEMS1-5
1.5 FUEL CELL TYPES1-7
1.5.1 Polymer Electrolyte Fuel Cell (PEFC1-9
1.5.2 Alkaline Fuel Cell (AFC1-10
1.5.3 Phosphoric Acid Fuel Cell (PAFC1-10
1.5.4 Molten Carbonate Fuel Cell (MCFC) 1-11
1.5.5 Solid Oxide Fuel Cell (SOFC) 1-12
1.6 CHARACTERISTICS1-12
1.7 ADVANTAGES/DISADVANTAGES1-14
1.8 APPLICATIONS, DEMONSTRATIONS, AND STATUS 1-15
1.8.1 Stationary Electric Power1-15
1.8.2 Distributed Generation 1-20
1.8.3 Vehicle Motive Power1-22
1.8.4 Space and Other Closed Environment Power 1-23
1.8.5 Auxiliary Power Systems 1-23
1.8.6 Derivative Applications1-32
1.9 REFERENCES1-32
2. FUEL CELL PERFORMANCE2-1
2.1 THE ROLE OF GIBBS FREE ENERGY AND NERNST POTENTIAL2-1
2.2 IDEAL PERFORMANCE 2-4
2.3 CELL ENERGY BALANCE2-7
2.4 CELL EFFICIENCY 2-7
2.5 ACTUAL PERFORMANCE2-10
2.6 FUEL CELL PERFORMANCE VARIABLES2-18
2.7 MATHEMATICAL MODELS2-24
2.7.1 Value-in-Use Models 2-26
2.7.2 Application Models2-27
2.7.3 Thermodynamic System Models2-27
2.7.4 3-D Cell / Stack Models 2-29
2.7.5 1-D Cell Models2-31
2.7.6 Electrode Models2-32
2.8 REFERENCES2-33
3. POLYMER ELECTROLYTE FUEL CELLS 3-1
3.1 CELL COMPONENTS3-1
3.1.1 State-of-the-Art Components 3-2
3.1.2 Component Development3-11
3.2 PERFORMANCE 3-14
3.3 PEFC SYSTEMS3-16
3.3.1 Direct Hydrogen PEFC Systems 3-16
3.3.2 Reformer-Based PEFC Systems3-17
3.3.3 Direct Methanol Fuel Cell Systems 3-19
3.4 PEFC APPLICATIONS3-21
3.4.1 Transportation Applications3-21
3.4.2 Stationary Applications 3-22
3.5 REFERENCES3-22
4. ALKALINE FUEL CELL4-1
4.1 CELL COMPONENTS4-5
4.1.1 State-of-the-Art Components 4-5
4.1.2 Development Components 4-6
4.2 PERFORMANCE 4-7
4.2.1 Effect of Pressure 4-8
4.2.2 Effect of Temperature 4-9
4.2.3 Effect of Impurities -11
4.2.4 Effects of Current Density4-12
4.2.5 Effects of Cell Life4-14
4.3 SUMMARY OF EQUATIONS FOR AFC4-14
4.4 REFERENCES4-16
5. PHOSPHORIC ACID FUEL CELL 5-1
5.1 CELL COMPONENTS5-2
5.1.1 State-of-the-Art Components 5-2
5.1.2 Development Components 5-6
5.2 PERFORMANCE 5-11
5.2.1 Effect of Pressure 5-12
5.2.2 Effect of Temperature 5-13
5.2.3 Effect of Reactant Gas Composition and Utilization 5-14
5.2.4 Effect of Impurities 5-16
5.2.5 Effects of Current Density5-19
5.2.6 Effects of Cell Life5-20
5.3 SUMMARY OF EQUATIONS FOR PAFC5-21
5.4 REFERENCES5-22
6. MOLTEN CARBONATE FUEL CELL 6-1
6.1 CELL COMPONENTS6-4
6.1.1 State-of-the-Art Componments 6-4
6.1.2 Development Components 6-9
6.2 PERFORMANCE 6-13
6.2.1 Effect of Pressure 6-15
6.2.2 Effect of Temperature 6-19
6.2.3 Effect of Reactant Gas Composition and Utilization 6-21
6.2.4 Effect of Impurities 6-25
6.2.5 Effects of Current Density6-30
6.2.6 Effects of Cell Life6-30
6.2.7 Internal Reforming 6-30
6.3 SUMMARY OF EQUATIONS FOR MCFC6-34
6.4 REFERENCES6-38
7. SOLID OXIDE FUEL CELLS7-1
7.1 CELL COMPONENTS7-2
7.1.1 Electrolyte Materials 7-2
7.1.2 Anode Materials 7-3
7.1.3 Cathode Materials 7-5
7.1.4 Interconnect Materials7-6
7.1.5 Seal Materials7-9
7.2 CELL AND STACK DESIGNS 7-13
7.2.1 Tubular SOFC 7-13
7.2.1.1 Performance 7-20
7.2.2 Planar SOFC7-31
7.2.2.1 Single Cell Performance7-35
7.2.2.2 Stack Performance7-39
7.2.3 Stack Scale-Up7-41
7.3 SYSTEM CONSIDERATIONS 7-45
7.4 REFERENCES7-45
8. FUEL CELL SYSTEMS8-1
8.1 SYSTEM PROCESSES 8-2
8.1.1 Fuel Processing 8-2
8.2 POWER CONDITIONING8-27
8.2.1 Introduction to Fuel Cell Power Conditioning Systems8-28
8.2.2 Fuel Cell Power Conversion for Supplying a Dedicated Load [2,3,48-29
8.2.3 Fuel Cell Power Conversion for Supplying Backup Power to a Load
Connected to a Local Utility 8-34
8.2.4 Fuel Cell Power Conversion for Supplying a Load Operating in Parallel
With the Local Utility (Utility Interactive) 8-37
8.2.5 Fuel Cell Power Conversion for Connecting Directly to the Local Utility8-37
8.2.6 Power Conditioners for Automotive Fuel Cells 8-39
8.2.7 Power Conversion Architecture for a Fuel Cell Turbine Hybrid Interfaced
With a Local Utility8-41
8.2.8 Fuel Cell Ripple Current 8-43
8.2.9 System Issues: Power Conversion Cost and Size8-44
8.2.10 REFERENCES (Sections 8.1 and 8.2) 8-45
8.3 SYSTEM OPTIMIZATION8-46
8.3.1 Pressure 8-46
8.3.2 Temperature 8-48
8.3.3 Utilization8-49
8.3.4 Heat Recovery8-50
8.3.5 Miscellaneous8-51
8.3.6 Concluding Remarks on System Optimization 8-51
8.4 FUEL CELL SYSTEM DESIGNS8-52
8.4.1 Natural Gas Fueled PEFC System 8-52
8.4.2 Natural Gas Fueled PAFC System 8-53
8.4.3 Natural Gas Fueled Internally Reformed MCFC System8-56
8.4.4 Natural Gas Fueled Pressurized SOFC System8-58
8.4.5 Natural Gas Fueled Multi-Stage Solid State Power Plant System 8-62
8.4.6 Coal Fueled SOFC System8-66
8.4.7 Power Generation by Combined Fuel Cell and Gas Turbine System 8-70
8.4.8 Heat and Fuel Recovery Cycles 8-70
8.5 FUEL CELL NETWORKS 8-82
8.5.1 Molten Carbonate Fuel Cell Networks: Principles, Analysis and
Performance 8-82
8.5.2 MCFC Network8-86
8.5.3 Recycle Scheme 8-86
8.5.4 Reactant Conditioning Between Stacks in Series8-86
8.5.5 Higher Total Reactant Utilization 8-87
8.5.6 Disadvantages of MCFC Networks8-88
8.5.7 Comparison of Performance8-88
8.5.8 Conclusions 8-89
8.6 HYBRIDS8-89
8.6.1 Technology8-89
8.6.2 Projects8-92
8.6.3 World’s First Hybrid Project8-93
8.6.4 Hybrid Electric Vehicles (HEV) 8-93
8.7 FUEL CELL AUXILIARY POWER SYSTEMS8-96
8.7.1 System Performance Requirements8-97
8.7.2 Technology Status8-98
8.7.3 System Configuration and Technology Issues 8-99
8.7.4 System Cost Considerations8-102
8.7.5 SOFC System Cost Structure 8-103
8.7.6 Outlook and Conclusions 8-104
8.8 REFERENCES8-104
9. SAMPLE CALCULATIONS9-1
9.1 UNIT OPERATIONS9-1
9.1.1 Fuel Cell Calculations 9-1
9.1.2 Fuel Processing Calculations 9-13
9.1.3 Power Conditioners9-16
9.1.4 Others 9-16
9.2 SYSTEM ISSUES9-16
9.2.1 Efficiency Calculations 9-17
9.2.2 Thermodynamic Considerations9-19
9.3 SUPPORTING CALCULATIONS9-22
9.4 COST CALCULATIONS9-25
9.4.1 Cost of Electricity9-25
9.4.2 Capital Cost Development 9-26
9.5 COMMON CONVERSION FACTORS 9-27
9.6 AUTOMOTIVE DESIGN CALCULATIONS9-28
9.7 REFERENCES9-29
10. APPENDIX 10-1
10.1 EQUILIBRIUM CONSTANTS 10-1
10.2 CONTAMINANTS FROM COAL GASIFICATION10-2
10.3 SELECTED MAJOR FUEL CELL REFERENCES, 1993 TO PRESENT10-4
10.4 LIST OF SYMBOLS10-10
10.5 FUEL CELL RELATED CODES AND STANDARDS10-14
10.5.1 Introduction10-14
10.5.2 Organizations 10-15
10.5.3 Codes & Standards10-16
10.5.4 Codes and Standards for Fuel Cell Manufacturers10-17
10.5.5 Codes and Standards for the Installation of Fuel Cells 10-19
10.5.6 Codes and Standards for Fuel Cell Vehicles 10-19
10.5.7 Application Permits10-19
10.5.8 References 10-21
10.6 FUEL CELL FIELD SITE DATA10-21
10.6.1 Worldwide Sites 10-21
10.6.2 DoD Field Sites 10-24
10.6.3 IFC Field Units10-24
10.6.4 FuelCell Energy10-24
10.6.5 Siemens Westinghouse10-24
10.7 HYDROGEN10-31
10.7.1 Introduction10-31
10.7.2 Hydrogen Production 10-32
10.7.3 DOE’s Hydrogen Research 10-34
10.7.4 Hydrogen Storage10-35
10.7.5 Barriers10-36
10.8 THE OFFICE OF ENERGY EFFICIENCY AND RENEWABLE ENERGY WORK IN FUEL
CELLS 10-36
10.9 RARE EARTH MINERALS 10-38
10.9.1 Introduction10-38
10.9.2 Outlook10-40
10.10 REFERENCES10-41
11. INDEX11-1
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