FOREWORD ........................................................ v
PUBLISHERS PREFACE ............................................. ix
A TRIBUTE .................................................... xxix
Part I: BASIC AND APPLIED ELECTROCHEMISTRY AS RELEVANT TO FUEL
CELLS
Chapter 1
EVOLUTION OF ELECTROCHEMISTRY
1.1. Electrochemistry: A Field Born Out Of Chemistry And
Electricity .............................................. 3
1.2. Scope of Electrochemistry ................................ 5
1.2.1. Electrochemistry and Surface Science
(Wet Electrochemistry) ................................... 5
1.2.2. Solid-State Science (Dry Electrochemistry) ............... 7
1.2.3. Colloid and Surface Science .............................. 9
1.2.4. Membrane Phenomena ...................................... 10
1.2.5. Bioelectrochemistry/Biomedical Sciences ................. 10
1.2.6. Electrochemical Engineering ............................. 11
1.2.7. Electrochemical Technology .............................. 12
1.2.8. Environmental Electrochemistry .......................... 12
1.3. Types of Electrochemical Reactions ...................... 13
1.3.1. Gas Evolution and Gas Consumption ....................... 13
1.3.2. Metal Deposition and Dissolution ........................ 14
1.3.3. Redox Reactions ......................................... 14
1.3.4. Electrodes of the Second Kind ........................... 14
1.3.5. Corrosion/Passivation ................................... 15
1.3.6. Electroorganic Reactions ................................ 16
1.3.7. Photoelectrochemical Reactions .......................... 16
1.3.8. Bioelectrochemistry and Electrophysiology ............... 17
1.4. Potentials at Electrode/Electrolyte Interfaces and
Electromotive Series .................................... 18
1.5. Free Energy Changes of Reactions and their Reversible
Potentials (Nernst Potentials) .......................... 21
Cited References ............................................... 24
Problems ....................................................... 24
Chapter 2
ELECTRODE/ELECTROLYTE INTERFACES: STRUCTURE AND KINETICS OF
CHARGE TRANSFER
2.1. Double Layer at electrode/electrolyte interfaces ........ 27
2.1.1. Structure, Charge, and Capacitance Characteristics ...... 27
2.1.1.1. Parallel Plate Condenser Model: Helmholtz
Model .......................................... 28
2.1.1.2. Diffuse Layer Model: Gouy and Chapman Model .... 28
2.1.1.3. Compact-Diffuse Layer Model: Stern Model ....... 31
2.1.1.4. Triple Layer Model: Esin and Markov, Grahame,
and Devanathan Model ........................... 32
2.1.1.5. Water Dipole Model: Bockris-Devanathan-Muller
Model .......................................... 32
2.1.2. Effect of Specific Adsorption of Ions on the Double
Layer Structure and their Adsorption Isotherms .......... 34
2.1.2.1. The Region of Constant Capacity at Negative
Potentials ..................................... 34
2.1.2.2. Capacity Hump .................................. 34
2.1.3. Effect of Adsorption of Neutral Molecules on
the Structure of the Double Layer ....................... 37
2.1.4. Brief Analysis of Structures of Semiconductor/
Electrolyte and Insulator/Electrolyte Interfaces ........ 41
2.2. Vital Need for Multi-Disciplinary Approach .............. 44
2.3. Single and Multi-Step Reactions ......................... 46
2.4. Concept of Rate-Determining Step ........................ 48
2.5. Dependence of Current Density on Potential for
Activation Controlled Reactions: Theoretical Analysis ... 53
2.5.1. Classical Treatment to Determine Electrode Kinetic
Parameters .............................................. 53
2.5.1.1. Expression for Current Density as a Function
of Potential ................................... 56
2.5.1.2. Reaction Orders, Transfer Coefficients, and
Stoichiometric Numbers ......................... 58
2.5.1.3. Exchange Current Density and Reversible
Potential ...................................... 59
2.5.2. Quantum Mechanical Treatment ............................ 61
2.6. Concept of Activation Overpotential, Expression for
current Density as a Function of Activation
Overpotential, and Charge Transfer Resistance ........... 65
2.7. Other Types of Rate Limitations and Overpotentials and
their Effects on Current Density Potential Behavior ..... 68
2.7.1. Mass Transport Overpotential ............................ 68
2.7.2. Case of Activation Plus Diffusion Controlled
Reactions ............................................... 72
2.7.3. Ohmic Overpotential ..................................... 73
2.8. Electrocatalysis ........................................ 74
2.8.1. Electrocatalysis Vital Role in Electrosynthesis and
Electrochemical Energy Conversion and Storage ........... 74
2.8.2. Distinctive Features of Electrocatalysis ................ 75
2.8.2.1. Net-electron Transfer in
Overall-Electrocatalytic Reaction .............. 75
2.8.2.2. Wide Range of Reaction Rates Attained by
Altering the Potential Across the Interface
at Constant Temperature ........................ 75
2.8.2.3. An Electrochemical Pathway for Chemical
Reactions ...................................... 75
2.8.2.4. Different Products in Different Ranges of
Potential ...................................... 76
2.8.2.5. Change in Path of Reactions Using Redox
Systems ........................................ 76
2.8.2.6. In-Situ Reactivation of Electrocatalysts ....... 76
2.8.2.7. Electrochemical Nature of Biological
Reactions ...................................... 77
2.8.3. Similarities Between Electrocatalysis and
Heterogeneous Catalysis ................................. 77
2.8.3.1. Effect of Geometric Factors .................... 77
2.8.3.2. Electronic Factors ............................. 78
2.8.4. At What Potentials Should One Compare Reaction Rates
to Elucidate the Roles of Electronic and Geometric
Factors? ................................................ 81
2.9. Adsorption Isotherms and Pseudocapacitance .............. 81
2.9.1. Types of Adsorption Isotherms and Their Influence on
Electrode Kinetics and Electrocatalysis ................. 81
2.9.1.1. Langmuir Isotherm .............................. 81
2.9.1.2. Temkin Isotherm ................................ 84
2.9.2. Adsorption Pseudocapacitance ............................ 86
2.9.2.1. What is Pseudocapacitance? ..................... 86
2.9.2.2. Theoretical Analysis of Dependence of
Pseudocapacitance on the Type of Adsorption
Isotherm ....................................... 87
2.9.2.3. Electrical Equivalent Circuits for Reactions
Exhibiting Pseudocapacitances .................. 89
Suggested Reading .............................................. 89
Cited References ............................................... 90
Problems ....................................................... 90
Chapter 3
ELECTROCHEMICAL TECHNOLOGIES AND APPLICATIONS
3.1. Role of Electrochemical Technologies in Chemical
Industry ................................................ 93
3.1.1. Background .............................................. 93
3.1.2. Principles of Technologies .............................. 93
3.2. Aluminum Production ..................................... 98
3.2.1. Background and Applications ............................. 98
3.2.2. Principles of Technology ................................ 99
3.2.3. Economics .............................................. 101
3.2.4. Energy Conservation Measures ........................... 102
3.2.5. Benefits to or from Fuel Cell Technologies ............. 104
3.3. Chlor-Alkali Technology ................................ 104
3.3.1. Background and Applications ............................ 104
3.3.2. Principles of Technology ............................... 104
3.3.3. Economics .............................................. 113
3.3.4. Benefits to or from Fuel Cell Technologies ............. 113
3.4. Electro-Organic Synthesis .............................. 115
3.4.1. Background and Applications ............................ 115
3.4.2. Principles of Technology ............................... 116
3.4.3. Economics .............................................. 125
3.4.4. Benefits to or from Fuel Cell Technology ............... 125
3.5. Electrowinning and Refining of Metals .................. 126
3.5.1. Background and Applications ............................ 126
3.5.2. Principles of Technology ............................... 126
3.5.3. Economics .............................................. 133
3.5.4. Benefits to or from Fuel Cell Technology ............... 134
3.6. Corrosion Inhibition/Passivation ....................... 136
3.6.1. Background ............................................. 136
3.6.2. Principles of Technologies ............................. 137
3.6.3. Benefits to or from Fuel Cell Technologies ............. 139
3.7. Electrochemical Energy Storage ......................... 141
3.7.1. Background ............................................. 141
3.7.2. Primary Batteries ...................................... 143
3.7.2.1. Zinc/Manganese Dioxide ........................ 143
3.7.2.2. Zinc/Air ...................................... 146
3.7.2.3. Lithium ....................................... 149
3.7.3. Secondary Batteries .................................... 151
3.7.3.1. Lead Acid ..................................... 151
3.7.3.2. Nickel/Hydrogen ............................... 154
3.7.3.3. Nickel/Cadmium ................................ 158
3.7.3.4. Nickel/Metal Hydride .......................... 161
3.7.3.5. Lithium - Ion ................................. 163
3.7.4. Reserve Batteries ...................................... 169
3.7.4.1. Background and Rationale ...................... 169
3.7.4.2. Mg-Seawater Activated ......................... 170
3.7.5. Thermal Batteries ...................................... 171
3.7.5.1. Background and Rationale ...................... 171
3.7.5.2. Principles of Technology and Performance
Characteristics ............................... 171
3.7.6. Electrochemical Capacitors ............................. 173
3.7.6.1. Introduction .................................. 173
3.7.6.2. Principles of Technology ...................... 173
3.7.6.3. Applications and Economics .................... 179
3.7.6.4. Benefits to or from Fuel Cell Technology ...... 180
3.8. Electrochemical Sensors ................................ 181
3.8.1. Background and Rationale ............................... 181
3.8.2. Principles of Technology ............................... 181
3.8.3. Applications and Economics ............................. 182
3.8.4. Benefits to or from Fuel Cell Technology ............... 182
Suggested Reading ............................................. 183
Cited References .............................................. 183
Problems ...................................................... 186
Part II: FUNDAMENTAL ASPECTS FOR RESEARCH AND DEVELOPMENT OF
FUEL CELLS
Chapter 4
FUEL CELL PRINCIPLES
4.1. Scope of Chapter ....................................... 189
4.2. Basic Similarities and Dissimilarities among
the Three Types of Electrochemical Technologies ........ 191
4.2.1. Table 4.1 .............................................. 194
4.2.2. Table 4.2 .............................................. 195
4.3. Types Of Fuel Cells .................................... 196
4.3.1. Evolutionary Aspects of Fuel Cells and their
Classifications ........................................ 196
4.3.2. Inventions and Demonstrations in 20th and 21st
Century ................................................ 200
4.3.2.1. 1904-1907 .................................... 200
4.3.2.2. 1910-1939 .................................... 200
4.3.2.3. 1932-1952 .................................... 200
4.3.2.4. 1938-1971 .................................... 200
4.3.2.5. 1935-1937 .................................... 200
4.3.2.6. 1948-1975 .................................... 200
4.3.2.7. 1950-1965 .................................... 201
4.3.2.8. 1938-1965 .................................... 201
4.3.2.9. 1959-1982 .................................... 201
4.3.2.10. 1965-1995 .................................... 201
4.3.2.11. 1958-present ................................. 201
4.3.2.12. 1965-present ................................. 202
4.4. Thermodynamic Aspects .................................. 202
4.4.1. Standard Free Energy and Enthalpy Change of a Fuel
Cell Reaction .......................................... 202
4.4.2. Effect of Temperature and Pressure on
the Thermodynamic-Reversible Potential, Er ............. 204
4.4.3. Thermodynamic Data for Some Fuel Cell Reactions ........ 205
4.5. Electrode Kinetic Aspects .............................. 206
4.5.1. Single Cell: the Heart of the Fuel Cell ................ 206
4.5.2. Role of Electrode Kinetics and Electrocatalysis on
the Performance of Fuel Cells .......................... 206
4.5.3. Cell Potential-Current Density Behavior of Fuel
Cells .................................................. 207
4.6. Analysis of Fuel Cell Performance Characteristics ...... 208
4.6.1. Cell Potential ......................................... 208
4.6.2. Efficiency ............................................. 209
4.6.3. Differential Resistance ................................ 210
4.6.4. Power Density .......................................... 210
4.6.5. Rate of Heat Generation ................................ 211
4.7. Effects of Electrode Kinetic Parameters on
Performance characteristics of PEMFCS and DMFCS ........ 212
4.7.1. Rationale for Selection of PEMFCs and DMFCs ............ 212
4.7.2. Methodology for Analysis ............................... 213
4.7.3. Effect of Exchange-Current Density ..................... 215
4.7.4. Tafel Slope ............................................ 221
4.7.5. Ohmic Resistance ....................................... 221
4.7.6. Mass Transport Parameters .............................. 222
Suggested Reading ............................................. 227
Cited References .............................................. 232
Problems ...................................................... 232
Chapter 5
ELECTROCATALYSIS OF FUEL CELL REACTIONS
5.1. Introduction ........................................... 235
5.1.1. Kinetics ............................................... 236
5.1.2. Electrocatalysis ....................................... 237
5.1.3. Electrocatalysts ....................................... 238
5.2. Fuel-Cell Reactions in Acid and Alkaline Fuel Cells .... 239
5.2.1. Oxygen Reduction in Acid Electrolytes .................. 239
5.2.2. Oxygen Reduction in Alkaline Electrolytes .............. 245
5.2.3. Hydrogen Oxidation in Acid Media ....................... 246
5.2.4. Hydrogen Oxidation in Alkaline Media ................... 251
5.2.5. Methanol Oxidation in Acid Media ....................... 251
5.2.6. Methanol Oxidation in Alkaline Media ................... 258
5.3. High-Temperature Fuel Cells ............................ 258
5.3.1. Molten-Carbonate Fuel Cell (MCFC) ...................... 259
5.3.2. Solid-Oxide Fuel Cell (SOFC) ........................... 260
Cited References .............................................. 262
Chapter 6
EXPERIMENTAL METHODS IN LOW TEMPERATURE FUEL CELLS
6.1. Catalyst ............................................... 268
6.1.1. Preparation Techniques ................................. 268
6.1.2. Catalyst Characterization: Physical .................... 269
6.1.3. Catalyst Characterization: Electrochemical ............. 271
6.1.3.1. Cyclic Voltammetric (CV) Measurements ......... 271
6.1.3.2. Rotating Disk Electrode (RDE) Method .......... 272
6.2. Electrode .............................................. 275
6.2.1. Fabrication of Gas Diffusion Electrodes ................ 276
6.2.1.1. Electrode Preparation ......................... 276
6.2.2. Physical Characterization .............................. 278
6.2.2.1. Electronic Resistivity ........................ 279
6.2.2.2. Porosimetry ................................... 279
6.2.3. Electrochemical Characterization ....................... 280
6.2.3.1. Cyclic-Voltammetric Evaluation ................ 280
6.2.3.2. Polarization Studies .......................... 280
6.2.3.3. Half-Cell Testing with Dissolved Fuel ......... 280
6.2.3.4. Gas-diffusion Electrode Evaluation ............ 280
6.2.3.5. Floating-Electrode Method ..................... 282
6.2.4. Choice of Reference Electrode for Half-Cell Studies .... 282
6.3. Full Cell .............................................. 286
6.3.1. MEA Fabrication ........................................ 286
6.3.1.1. Hot-Pressing Method ........................... 286
6.3.1.2. Decal-Transfer Method ......................... 286
6.3.1.3. Reference Electrode Incorporation in Full
Cells ......................................... 287
6.3.2. Liquid-Electrolyte Cells ............................... 287
6.3.3. Cell Hardware and Cell Build ........................... 289
6.3.4. Instrumentation ........................................ 291
6.3.5. Cell Start-Up Procedures ............................... 293
6.3.5.1. Wet-Up Process ................................ 293
6.3.5.2. Cross-Over Test ............................... 293
6.3.5.3. Break-In Procedure ............................ 293
6.3.6. Cell Testing - Н2O2 Cells .............................. 294
6.3.6.1. Open-Circuit Test ............................. 294
6.3.6.2. Cell Voltage as a Function of Current
Density ....................................... 294
6.3.6.3. Reactant Flow Rates ........................... 295
6.3.6.4. Humidification Level .......................... 295
6.3.6.5. Effect of Reactant Pressure ................... 295
6.3.7. Diagnostic Methods: H2/O2 Cells ........................ 295
6.3.7.1. Resistance Measurement ........................ 295
6.3.7.2. Polarization Data Analysis .................... 298
6.3.7.3. Catalyst Activity ............................. 299
6.3.7.4. In-Situ CV Experiment ......................... 300
6.3.7.5. Limiting currents (N2/O2 vs. He/O2) ............ 301
6.3.7.6. Impedance Spectroscopy ........................ 302
6.3.8. Cell Testing: DMFC ..................................... 302
6.3.8.1. Differences ................................... 302
6.3.8.2. Open Circuit Voltage .......................... 303
6.3.8.3. Current-Voltage Performance ................... 303
6.3.8.4. Cross-Over and Fuel Efficiency
Determination ................................. 303
6.3.9. Diagnostics: DMFC ...................................... 304
6.4. Post Cell Test Analyses ................................ 305
6.4.1. Catalyst Area .......................................... 305
6.4.1.1. Electrochemical Methods ....................... 305
6.4.1.2. Physical Methods .............................. 305
Cited References .............................................. 306
Part III: ENGINEERING AND TECHNOLOGY DEVELOPMENT ASPECTS OF
FUEL CELLS
Chapter 7
MODELING ANALYSES: FROM HALF-CELL TO SYSTEMS
7.1. General Overview of Modeling Analyses .................. 311
7.1.1. The Role of Simulation in Fuel Cell R&D ................ 311
7.1.2. Modeling of Electrode and Electrolyte Overpotentials ... 313
7.2. Modeling of Half-cell reactions: Electrode Potential
versus Current Density Behavior and Current
Distribution in Active Layer ........................... 314
7.2.1. Vital Need of Porous Gas Diffusion Electrodes for
Fuel Cells to Enhance 3-D Reaction Zone ................ 314
7.2.2. Evolution of Physicochemical Models for Porous
Gas-Diffusion Electrodes and Performance Analyses ...... 317
7.2.2.1. Simple Pore Model with Parallel Cylindrical
Pores ......................................... 317
7.2.2.2. Thin Film Model ............................... 319
7.2.2.3. Finite Contact Angle Meniscus Model ........... 320
7.2.2.4. Intersecting Pore Model ....................... 320
7.2.2.5. Agglomerate Model ............................. 322
7.2.2.6. Macro-Homogeneous Model ....................... 324
7.2.3. General Treatment Based on Three Basic Equations ....... 324
7.2.3.1. Basic Aspects Relevant to All Types of Fuel
Cells ......................................... 324
7.2.3.2. Application to 3-Phase Electrodes
(PEMFC, AFC, PAFC, DMFC, and MCFC):
the Agglomerate Model ......................... 328
7.2.3.3. Application to 2-Phase Electrodes (SOFC):
Simulation of Composite Electrodes ............ 335
7.3. Electrolyte Overpotentials: Limits of Applicability
of Ohm's Law ........................................... 340
7.3.1. General Treatment of Electrolyte Overpotentials ........ 340
7.3.1.1. Nafion Electrolyte: Water Transport Problems
and Their Effect on Electrical Conductivity ... 343
7.4. Additional efficiency losses at single-cell level ...... 348
7.4.1. Overview ............................................... 348
7.4.2. Mass Balances .......................................... 349
7.4.3. Energy Balance in Gaseous Phase ........................ 350
7.4.4. Energy Balance of Solid Structure ...................... 351
7.4.5. Numerical Integration and Boundary Conditions .......... 351
7.4.6. Application to PEMFCs .................................. 351
7.4.7. Application to SOFCs ................................... 356
7.5. Further efficiency losses in cell stacks ............... 359
7.5.1. Overview .............................................. 359
7.5.2. Fluid Dynamics of Fuel Cell Stacks ..................... 360
7.5.3. Impact of Fluid-Dynamic Effects on Stack Performance ... 362
7.6. Modeling Of Fuel Cell Power Plants ..................... 363
7.6.1. Overview ............................................... 363
7.6.2. Example: Simulation of a 300 kWc SOFC/Gas Turbine
Hybrid System .......................................... 364
Suggested Reading ............................................. 369
Problems ...................................................... 371
Chapter 8
FUELS: PROCESSING, STORAGE, TRANSMISSION, DISTRIBUTION,
AND SAFETY
8.1. Hydrogen: The Ideal Fuel ............................... 375
8.1.1. Hydrogen: The Most Electroactive and Environmentally
Clean Fuel for All Types of Fuel Cells ................. 375
8.1.2. A Modus Operandi fora Hydrogen Energy Scenario ......... 378
8.1.3. Fossil Fuels: The Main Source of Hydrogen for
the Foreseeable Future ................................. 380
8.1.4. Natural Gas: The Most Promising Fuel for All Types of
Fuel Cells ............................................. 381
8.1.5. Coal Gasifiers for Hydrogen Production ................. 383
8.2. Fuel Processors for Integration with Fuel Cells ........ 384
8.2.1. Steam-Reforming, Shift-Conversion, Pressure Swing,
and Adsorption of Natural Gas for Ultra-Pure H2
Production for AFCs and PEMFCs ......................... 384
8.2.2. Steam Reforming, Shift Conversion, and Preferential
Oxidation of Natural Gas, Gasoline or Methanol for
PEMFCs ................................................. 385
8.2.3. Steam-Reforming and Shift-Conversion of Natural Gas
or Methanol for H2 Production for PAFCs ................ 388
8.2.4. Partial Oxidation and Shift Conversion of
Hydrocarbons and Alcohols for PEMFCs ................... 389
8.2.5. Autothermal Reforming of Methanol and Gasoline for
PEMFC Powered Vehicles ................................. 390
8.2.6. Steam Reforming of Natural Gas for MCFC or SOFC:
Gas Turbine Hybrids .................................... 394
8.2.7. Coal Gasifiers for SOFC/Gas Turbine Hybrids, with H2
Separation and CO2 Sequestration ....................... 397
8.3. Hydrogen Production From Nuclear And Renewable Energy
Resources .............................................. 398
8.3.1. Role of Nuclear and Renewable Energy Resources ......... 398
8.3.2. Water Electrolysis ..................................... 400
8.3.2.1. Thermodynamic and Electrode Kinetic Aspects ... 400
8.3.2.2. Types of Water Electrolyzers and Status of
Technologies .................................. 402
8.3.3. Photoelectrolysis ...................................... 407
8.3.4. Thermochemical Decomposition of Water .................. 409
8.3.5. Biomass Fuel Production and Conversion to Hydrogen ..... 411
8.3.6. Biological/Biochemical Production of Hydrogen .......... 413
8.4. Other Fuels for Direct or Indirect Utilization in
Fuel Cells ............................................. 414
8.4.1. Partially-Oxygenated Carbonaceous Fuels ................ 414
8.4.1.1. Methanol and Ethanol .......................... 414
8.4.1.2. Dimethyl Ether (DME) .......................... 416
8.4.2. Nitrogenous Fuels ...................................... 417
8.4.2.1. General Comments .............................. 417
8.4.2.2. Ammonia ....................................... 418
8.4.2.3. Hydrazine ..................................... 419
8.5. Fuel Storage ........................................... 419
8.5.1. Hydrogen ............................................... 419
8.5.1.1. Multifold Options but Many Challenges ......... 419
8.5.1.2. Compressed Hydrogen Stored Underground for
Power Generation .............................. 419
8.5.1.3. Compressed Hydrogen Storage in Cylinders
Tanks for Transportation and Portable Power ... 421
8.5.1.4. Liquid Hydrogen Storage for Space, Military,
and Transportation Applications ............... 421
8.5.1.5. Solid Storage of Hydrogen as Metal Hydrides ... 424
8.5.2. Hydrogen Storage in Combination with Other Elements
or Compounds ........................................... 429
8.5.3. Techno-economic Analysis of Hydrogen Storage ........... 429
8.6. Fuel Transmission and Distribution: Hydrogen Versus
other Alternate Fuels .................................. 430
8.7. Fuel Safety: Hydrogen versus Alternate Fuels ........... 431
Suggested Reading ............................................. 432
Cited References .............................................. 434
Problems ...................................................... 436
Part IV: APPLICATIONS, TECHNO-ECONOMIC ASSESSMENTS,
AND PROGNOSIS OF FUEL CELLS
Chapter 9
STATUS OF FUEL CELL TECHNOLOGIES
9.1. Scope of Chapter ....................................... 441
9.2. Proton Exchange Membrane Fuel Cells (PEMFC) ............ 442
9.2.1. Evolutionary Aspects ................................... 442
9.2.2. Research and Development of High Performance Single
Cells .................................................. 444
9.2.2.1. Design, Component Materials and Assembly ...... 444
9.2.2.2. Optimization of Structure of Membrane and
Electrode Assembly (MEA) ...................... 446
9.2.2.3. Mode of Operation/Operating Conditions ........ 450
9.2.2.4. Physicochemical Characterization of Single
Cell and its Components ....................... 451
9.2.2.5. Performance Characteristics of Single Cells ... 459
9.2.3. Technology Development of Cell Stacks .................. 476
9.2.3.1. Scale-up of Single Cells ...................... 476
9.2.3.2. Bipolar Plates and Flow Fields ................ 477
9.2.3.3. Assembly of Electrochemical Cells Stacks ...... 478
9.2.3.4. Water Management .............................. 479
9.2.3.5. Thermal Management ............................ 481
9.2.3.6. Performance Evaluation ........................ 484
9.3. Direct Methanol Fuel Cells (DMFC) ...................... 484
9.3.1. Evolutionary Aspects ................................... 484
9.3.2. Research and Development of High Performance Single
Cells .................................................. 486
9.3.2.1. Cell Design and Assembly ...................... 486
9.3.2.2. Performance Characteristics ................... 488
9.3.3. Technology Development of Cell Stacks .................. 492
9.3.3.1. Low Power Level (100W - 5kW) .................. 492
9.3.3.2. Ultra-Low Power Levels (1 to 100W) ............ 494
9.4. Alkaline Fuel Cells (AFC) .............................. 497
9.4.1. Evolutionary Aspects ................................... 497
9.4.2. Research and Development of High Performance Single
Cells .................................................. 498
9.4.2.1. Cell Design, Assembly and Operating
Conditions .................................... 498
9.4.2.2. Performance Characteristics ................... 501
9.4.2.3. Technology Development of Cell Stacks ......... 502
9.5. Phosphoric-Acid Fuel Cells (PAFC) ...................... 505
9.5.1. Evolutionary Aspects ................................... 505
9.5.2. Research and Development of High-Performance Single
Cells .................................................. 508
9.5.2.1. Design, Assembly and Operating Conditions ..... 508
9.5.2.2. Performance Characteristics ................... 508
9.5.3. Technology Development of Cell Stacks .................. 513
9.6. Molten Carbonate Fuel Cells (MCFC) ..................... 515
9.6.1. Evolutionary Aspects ................................... 515
9.6.2. Single cells ........................................... 515
9.6.2.1. Design, Assembly and Operating Conditions ..... 515
9.6.2.2. Performance Characteristics ................... 517
9.6.3. Cell Stacks ............................................ 525
9.6.3.1. Design, Assembly and Operating
Characteristics ............................... 525
9.6.3.2. Performance Characteristics ................... 527
9.7. Solid-Oxide Fuel Cells (SOFC) .......................... 528
9.7.1. Evolutionary Aspects ................................... 528
9.7.2. Single Cells ........................................... 529
9.7.2.1. Design, Assembly and Operating Conditions ..... 529
9.7.2.2. Performance Characteristics ................... 536
9.7.3. Cell Stacks: Design, Assembly and Performance
Characteristics ........................................ 539
9.7.3.1. Siemens-Westinghouse Tubular SOFCs ............ 539
9.7.3.2. Planar SOFCs .................................. 540
9.8. Comparative Assessment of Six Leading Fuel Cell
Technologies ........................................... 542
9.8.1. Essential Characteristics: Single Cell Level ........... 542
9.8.1.1. General Comments .............................. 542
9.8.1.2. Fuel .......................................... 544
9.8.1.3. Operating Temperature ......................... 544
9.8.1.4. Electrolyte and Ionic Conductor ............... 544
9.8.1.5. Efficiency and Power Density .................. 546
9.8.1.6. Electrocatalysts/Loadings ..................... 546
9.8.1.7. Poisoning Species ............................. 547
9.8.1.8. Lifetime/Degradation Rate ..................... 547
9.8.2. Cell Stacks ............................................ 548
9.8.2.1. General Comments .............................. 548
9.8.2.2. Electrode Area ................................ 548
9.8.2.3. Bipolar Plate ................................. 548
9.8.2.4. Rated Power ................................... 551
9.8.2.5. Cogeneration .................................. 551
9.8.2.6. Efficiency .................................... 551
9.8.2.7. Coolant ....................................... 551
9.8.2.8. Lifetime ...................................... 552
9.8.3. Techno-Economic Challenges to Reach Era of Terrestrial
Applications in the 21st Century ....................... 552
9.8.3.1. PEMFCs ........................................ 552
9.8.3.2. DMFCs ......................................... 553
9.8.3.3. AFCs .......................................... 553
9.8.3.4. PAFCs ......................................... 553
9.8.3.5. MCFCs ......................................... 553
9.8.3.6. SOFCs ......................................... 553
9.9. Other Types of Fuel Cells .............................. 554
9.9.1. Carbonaceous Fuels ..................................... 554
9.9.1.1. Higher Hydrocarbons ........................... 554
9.9.1.2. Direct Ethanol Fuel Cells (DMFC) .............. 556
9.9.2. Nitrogeneous Fuels ..................................... 558
9.9.2.1. Ammonia ....................................... 558
9.9.2.2. Hydrazine ..................................... 559
9.9.3. Metal Fuels ............................................ 560
9.9.3.1. Zinc .......................................... 560
9.9.3.2. Aluminum ...................................... 561
9.9.4. Regenerative Fuel Cells ................................ 561
9.9.4.1. Electrical: Hydrogen/Oxygen and Hydrogen/
Halogen ....................................... 561
9.9.4.2. Solar: Photovoltatic Power Plants for
the Decomposition of H2 and HBr ............... 563
9.9.5. Thermal ................................................ 564
9.9.6. Radiochemical .......................................... 564
9.9.7. Biochemical ............................................ 565
9.9.7.1. Biogalvanic Cells ............................. 565
9.9.7.2. Biofuel Cells ................................. 566
9.9.7.3. The Predominantly Electrochemical Nature of
Biological Power Producing Reactions .......... 568
Cited References .............................................. 569
Chapter 10
APPLICATIONS AND ECONOMICS OF FUEL-CELL POWER PLANTS/
POWER SOURCES
10.1. Scope of Chapter ...................................... 575
10.2. Power Generation/Cogeneration ......................... 576
10.2.1. High Power Level (lOOkW to MWs) ....................... 576
10.2.1.1. Fuel-Cell Energy MCFC and MCFC/GT Hybrid
Power Plants ................................ 576
10.2.1.2. Ansaldo Ricerche (ARI, Italy), 100 kW MCFC
Power Plant ................................. 580
10.2.1.3. IHI (Japan) 100-kW MCFC Power Plants ........ 582
10.2.1.4. UTC-Fuel Cells 200-kW PAFC, PC 25, Power
Plant ....................................... 582
10.2.1.5. Siemens-Westinghouse Tubular SOFC Power
Plant (100-500 kW) .......................... 586
10.2.1.6. Ballard 250-kW PEMFC Power Plant ............ 588
10.2.2. Low to Medium Power Generation (5 to 100 kW) .......... 588
10.2.2.1. Plug Power 5-kW Power Plant ................. 588
10.2.2.2. General Electric 5-kW Planar SOFC Power
Plant ....................................... 589
10.3. Transportation ........................................ 590
10.3.1. Daimler-Chrysler PEMFC Powered Vehicles ............... 590
10.3.2. General Motors/Opel PEMFC Powered Vehicles ............ 591
10.3.3. Toyota PEMFC/NiMHx Powered Vehicle .................... 592
10.3.4. Honda PEMFC/Carbon Ultracapacitor Hybrid Vehicle ...... 594
10.3.5. Paul Scherrer Institute/Volkswagen AG/
FEV Motorrentechnick GMB-1/Montena Components PEMFC
Ultracapacitor Powered Automobile ..................... 594
10.3.6. Siemens PEMFC Propulsion System for Submarines ........ 597
10.4. Portable Power ........................................ 597
10.4.1. NASA's Space Shuttle AFC Power Plant .................. 597
10.4.2. Power Sources for Commercial and Aerospace
Applications: Low Power Level (100 W to 5 kW) ......... 598
10.4.3. Power Sources for Commercial Applications: Ultra-Low
Power Level (1 to 100W) ............................... 598
10.5. Economic Perspectives and Technical Challenges ........ 600
10.5.1. Rationale for this Section and a Look-back at
the Past 50 years ..................................... 600
10.5.2. Largest Impact for Fuel Cells Entering the Energy
Sector: Energy Conservation and Significantly
Lowering Environmental Pollution ...................... 602
10.5.3. Finding Niche Markets for the Entry of Fuel Cells in
the Energy Sector ..................................... 602
10.5.4. Cost Target for the Three-Main Applications and
the Need for a Realistic Cost-Benefit Analysis ........ 602
10.5.5. Importance of Cost Reduction of Component Materials
and Fabrication ....................................... 603
10.5.6. Performance Degradation and Operational Costs ......... 604
10.5.7. Technical and Economical Challenges ................... 604
Suggested Reading ............................................. 605
Chapter 11
COMPETING TECHNOLOGIES
11.1 Scope of Chapter ...................................... 607
11.1.1. Technology Comparison ................................. 607
11.1.2. Power Generation and Transportation ................... 607
11.1.3. Environmental Considerations .......................... 608
11.1.4. Portable Power Applications ........................... 608
11.2. Power Generation and Cogeneration ..................... 609
11.2.1. Electricity Generation in a Global Energy Context ..... 609
11.2.2. Fossil-Fuel Based Thermal Power Plants ................ 609
11.2.2.1. Operating Principles: Steam Cycle ........... 609
11.2.2.2. Operating Principles: Gas Turbine Cycle ..... 611
11.2.2.3. Thermal-Power-Plant Efficiency .............. 611
11.2.2.4. Combustion and Environmental Concerns ....... 612
11.2.3. Coal-Based Steam Power Cycles ......................... 614
11.2.3.1. Operating Principles: System
Configurations .............................. 614
11.2.3.2. Thermal Efficiency Considerations ........... 614
11.2.3.3. Emissions and Control ....................... 614
11.2.3.4. System Considerations ....................... 615
11.2.4. Natural-Gas Turbine Power Systems ..................... 615
11.2.4.1. General Comments on Gas Turbine Systems ..... 615
11.2.4.2. System Configurations for Turbine Systems ... 615
11.2.4.3. Efficiency Considerations ................... 616
11.2.4.4. Emissions and Control ....................... 617
11.2.4.5. Economic and System Considerations .......... 617
11.2.5. Nuclear Based Thermal Power Plants .................... 617
11.2.5.1. General Comments on Nuclear-Power Systems ... 617
11.2.5.2. Operating Principles and System
Configurations .............................. 618
11.2.5.3. Efficiency Considerations ................... 619
11.2.5.4. Environmental and Public Concerns ........... 619
11.2.6. Hydroelectric Power Plants ............................ 620
11.2.6.1. Operating Principles ........................ 620
11.2.6.2. Performance Characteristics ................. 621
11.2.6.3. System Aspects and Economics ................ 622
11.2.6.4. Environmental Benefits and Concerns ......... 622
11.2.7. Photovoltaic Power Generation ......................... 623
11.2.7.1. Background and Operating Principles ......... 623
11.2.7.2. Performance Characteristics ................. 623
11.2.7.3. Systems Aspects and Economics ............... 624
11.2.7.4. Environmental Benefits and Concerns ......... 625
11.2.8. Solar-Thermal Systems ................................. 625
11.2.8.1. Background and Operating Principles ......... 625
11.2.8.2. Performance Characteristics ................. 627
11.2.8.3. Systems Aspects, Applications, and
Economics ................................... 627
11.2.8.4. Environmental Benefits and Concerns ......... 627
11.2.9. Wind Energy Systems ................................... 628
11.2.9.1. Background and Operating Principles ......... 628
11.2.9.2. Performance Characteristics ................. 629
11.2.9.3. Systems Aspects and Economics ............... 630
11.2.9.4. Environmental Benefits and Concerns ......... 630
11.2.10. Geothermal Energy Systems ............................ 631
11.2.10.1. Background and Operating Principles ........ 631
11.2.10.2. Performance characteristics and System
Configurations ............................. 631
11.2.10.3. Systems Aspects and Economics .............. 632
11.2.10.4. Environment Emissions Concerns ............. 632
11.2.11. Ocean Energy Systems ................................. 632
11.2.11.1. General Comments on Types of Systems ....... 632
11.2.11.2. Tidal-Barrage Energy Systems ............... 633
11.2.11.3. Wave Energy Systems ........................ 633
11.2.11.4. Tidal Marine Currents ...................... 633
11.2.11.5. Ocean Therma- Energy Converters (OTEC) ..... 633
11.3. Small-Scale Remote and Distributed Power .............. 634
11.3.1. Background ............................................ 634
11.3.2. Small-Scale Generation Technologies ................... 634
11.3.2.1. General Comments ............................ 634
11.3.2.2. Reciprocating Engines ....................... 635
11.3.2.3. Microturbines ............................... 635
11.3.2.4. Renewable Sources ........................... 635
11.3.2.5. Nuclear Sources ............................. 636
11.4. Transportation-Automotive Power Plants ................ 636
11.4.1. Perspectives .......................................... 636
11.4.2. Internal-Combusion Engine ............................. 637
11.4.2.1. Design Types ................................ 637
11.4.2.2. Principles of Operation ..................... 637
11.4.2.3. Work, Power, Efficiency, and Fuel Economy ... 638
11.4.3. Internal-Combustion Engines: Spark-Ignition Engines ... 639
11.4.3.1. Design and Principles of Operation .......... 639
11.4.3.2. Thermal Efficiency and Fuel Efficiency ...... 639
11.4.3.3. Environmental Impacts: Emissions ............ 640
11.4.3.4. Typical Power Levels for Specific
Applications ................................ 640
11.4.4. Internal Combustion Engines: Compression Ignition
(Diesel) .............................................. 642
11.4.4.1. Applications and Principles of Operation .... 642
11.4.4.2. Thermal Efficiency and Fuel Efficiency ...... 642
11.4.4.3. Environmental Impacts: Emissions ............ 643
11.4.4.4. Power Levels and Performance Factors ........ 643
11.4.5. Electric-Vehicle Power Plants ......................... 643
11.4.5.1. General Comments ............................ 643
11.4.5.2. Principles of Operation ..................... 644
11.4.5.3. System Issues ............................... 644
11.4.5.4. Environmental Benefits ...................... 645
11.4.6. Hybrid Powered Vehicles ............................... 645
11.4.6.1. Unique Characteristics and Benefits ......... 645
11.4.6.2. Fundamentals of System Operation ............ 645
11.4.6.3. Thermal Efficiency and Fuel Efficiencies .... 645
11.4.6.4. Emissions and Control ....................... 648
11.5. Portable Power ........................................ 648
11.5.1. Background ............................................ 648
11.5.2. Batteries ............................................. 648
11.5.3. Environmental Aspects ................................. 649
11.5.4. Other Energy Storage Devices .......................... 649
11.5.4.1. Flywheels ................................... 649
11.5.4.2. Compressed Air .............................. 649
11.5.4.3. Ultracapacitors ............................. 650
11.6. Techno-Economic Assessments: Fuel Cells and
Competing Technologies ................................ 650
11.6.1. General Comments ...................................... 650
11.6.2. Power Generation/Cogeneration ......................... 651
11.6.3. Small-Scale Remote and Distributed Power .............. 654
11.6.4. Transportation ........................................ 655
11.6.5. Portable Power ........................................ 657
11.6.6. Conclusions ........................................... 658
Suggested Reading ............................................. 659
Problems ...................................................... 661
Chapter 12
CONCLUSIONS AND PROGNOSIS ..................................... 663
INDEX ......................................................... 671
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