Preface ....................................................... vii
1 Renewable Energy and the Hydrogen Economy ..................... 1
Krishnan Rajeshwar, Robert McConnell, Kevin Harrison, and
Stuart Licht
1 Renewable Energy and the Terawatt Challenge ................. 1
2 Hydrogen as a Fuel of the Future ............................ 3
3 Solar Energy and the Hydrogen Economy ...................... 11
4 Water Splitting and Photosynthesis ......................... 12
5 Completing the Loop: Fuel Cells ............................ 14
6 Concluding Remarks ......................................... 16
References ................................................. 16
2 The Solar Resource ........................................... 19
Daryl R. Myers
1 Introduction: Basic Properties of the Sun .................. 19
2 The Spectral Distribution of the Sun as a Radiation
Source ..................................................... 20
3 The Earth's Atmosphere as a Filter ......................... 22
4 Utilization of Solar Spectral Regions: Spectral Response
of Materials ............................................... 25
5 Reference Spectral Distributions ........................... 32
6 Summary .................................................... 38
References ................................................. 38
3 Electrolysis of Water ........................................ 41
Kevin Harrison and Johanna Ivy Levene
1 Introduction ............................................... 41
2 Electrolysis of Water ...................................... 43
2.1 Alkaline ............................................... 44
2.2 Proton Exchange Membrane ............................... 45
3 Fundamentals of Water Electrolysis ......................... 50
3.1 First Principles ....................................... 50
3.2 Overpotentials ......................................... 52
4 Commercial Electrolyzer Technologies ....................... 54
5 Electrolysis System ........................................ 55
5.1 Energy Efficiency ...................................... 56
5.2 Electricity Costs ...................................... 58
6 Opportunities for Renewable Energy ......................... 59
7 Conclusions ................................................ 60
References ................................................. 61
4 A Solar Concentrator Pathway to Low-Cost Electrolytic
Hydrogen ..................................................... 65
Robert McConnell
1 Direct Conversion of Concentrated Sunlight to
Electricity ................................................ 65
2 The CPV Market ............................................. 66
3 Higher and Higher Conversion Efficiencies .................. 69
4 CPV Reliability ............................................ 72
5 Following in Wind Energy's Footsteps ....................... 73
6 Low-Cost Hydrogen from Hybrid CPV Systems .................. 75
7 Describing the Hybrid CPV System ........................... 76
8 Discussion ................................................. 81
9 Hydrogen Vision Using Hybrid Solar Concentrators ........... 82
10 Conclusions ............................................... 83
Acknowledgements .......................................... 84
References ................................................ 84
5 Thermochemical and Thermal/Photo Hybrid Solar Water
Splitting .................................................... 87
Stuart Licht
1 Introduction to Solar Thermal Formation of Hydrogen ........ 87
1.1 Comparison of Solar Electrochemical, Thermal & Hybrid
Water Splitting ........................................ 87
2 Direct Solar Thermal Water Splitting to Generate Hydrogen
Fuel ....................................................... 90
2.1 Development of Direct Solar Thermal Hydrogen ........... 90
2.2 Theory of Direct Solar Thermal Hydrogen Generation ..... 91
2.3 Direct Solar Thermal Hydrogen Processes ................ 92
3 Indirect (Multi-step) Solar Thermal Water Splitting to
Generate Hydrogen Fuel ..................................... 94
3.1 Historical Development of Multi-Step Thermal
Processes for Water Electrolysis ....................... 94
3.2 Comparison of Multi-step Indirect Solar Thermal
Hydrogen Processes ..................................... 96
3.3 High-Temperature, Indirect-Solar Thermal Hydrogen
Processes .............................................. 96
4 Hybrid Solar Thermal/Electrochemical/Photo (STEP) Water
Splitting .................................................. 99
4.1 Historical Development of Hybrid Thermal Processes ..... 99
4.2 Theory of Hybrid Solar Hydrogen Generation ............. 99
4.3 Elevated Temperature Solar Hydrogen Processes and
Components ............................................ 111
5 Future Outlook and Concluding Remarks ..................... 116
References ................................................ 116
6 Molecular Approaches to Photochemical Splitting of Water .... 123
Frederick M. MacDonnell
1 Scope ..................................................... 123
2 Fundamental Principles .................................... 124
3 Nature's Photosynthetic Machinery ......................... 125
4 Design of Artificial Photosystems ......................... 129
5 The Ideal Sensitizer: Does Rubpy Come Close? .............. 133
5.1 Stability ............................................. 133
5.2 Photophysics and Photochemistry ....................... 136
6 Supramolecular Assemblies: Dyads, Triads and Beyond ....... 138
6.1 Energy Transfer Quenching: Antenna Complexes .......... 138
6.2 Bichromophores: Increasing Excited-State Lifetimes .... 140
6.3 Reductive and Oxidative Quenching: Dyads and Triads
with Donors and Acceptors ............................. 142
6.4 Single versus Multi-Electron Processes ................ 145
7 OER and HER Co-Catalysts .................................. 150
7.1 Mimicking the Oxygen Evolving Center: Water
Oxidation Catalysts ................................... 150
7.2 The Hydrogen Evolving Reaction (HER): Hydrogen
Evolution Catalysts ................................... 153
8 Future Outlook and Concluding Remarks ..................... 154
Acknowledgements .......................................... 156
References ................................................ 156
7 Hydrogen Generation from Irradiated Semiconductor-Liquid
Interfaces .................................................. 167
Krishnan Rajeshwar
1 Introduction and Scope .................................... 167
2 Types of Approaches ....................................... 170
3 More on Nomenclature and the Water Splitting Reaction
Requirements .............................................. 172
4 Efficiency of Photoelectrolysis ........................... 178
5 Theoretical Aspects ....................................... 180
6 Oxide Semiconductors ...................................... 183
6.1 Titanium Dioxide: Early Work .......................... 183
6.2 Studies on the Mechanistic Aspects of Processes at
the TiO2-Solution Interface ........................... 186
6.3 Visible Light Sensitization of TiO2 ................... 186
6.4 Recent Work on TiO2 on Photosplitting of Water or on
the Oxygen Evolution Reaction ......................... 187
6.5 Other Binary Oxides ................................... 190
6.6 Perovskite Titanates and Related Oxides ............... 192
6.7 Tantalates and Niobates ............................... 197
6.8 Miscellaneous Multinary Oxides ........................ 198
7 Nitrides, Oxynitrides and Oxysulfides ..................... 200
8 Metal Chalcogenide Semiconductors ......................... 202
8.1 Cadmium Sulfide ....................................... 202
8.2 Other Metal Chalcogenides ............................. 204
9 Group III-V Compound Semiconductors ....................... 205
10 Germanium and Silicon .................................... 206
11 Silver Halides ........................................... 208
12 Semiconductor Alloys and Mixed Oxides .................... 208
12.1 Semiconductor Composites ............................ 208
13 Photochemical Diodes and Twin-Photosystem
Configurations for Water Splitting ....................... 210
14 Other Miscellaneous Approaches and Hydrogen Generation
from Media Other than Water .............................. 211
15 Concluding Remarks ....................................... 213
Acknowledgments .......................................... 213
References ............................................... 213
8 Photobiological Methods of Renewable Hydrogen Production .... 229
Maria L. Ghirardi, Pin Ching Maness, and Michael
Seibert
1 Introduction .............................................. 229
2 Green Algae ............................................... 230
2.1 Mechanism of Hydrogen Production ...................... 230
2.2 Hydrogenase-Catalyzed H2 Production ................... 233
2.3 [FeFe]-hydrogenases ................................... 234
3 Cyanobacteria ............................................. 235
3.1 Mechanisms of Hydrogen Production ..................... 235
3.2 Hydrogenase-Catalyzed H2 Production ................... 236
3.3 [NiFe]-Hydrogenases ................................... 238
3.4 Nitrogenase-Catalyzed H2 Production ................... 240
3.5 Nitrogenases .......................................... 241
4 Other Systems ............................................. 242
4.1 Non-Oxygenic Purple, Non-Sulfur Photosynthetic
Bacteria .............................................. 242
4.2 Mixed Light/Dark Systems .............................. 243
4.3 Bio-Inspired Systems .................................. 244
5 Scientific and Technical Issues ........................... 245
5.1 General ............................................... 245
5.2 Oxygen Sensitivity of [FeFe]-Hydrogenases ............. 246
5.3 Oxygen Sensitivity of [NiFe]-Hydrogenases ............. 248
5.4 Competition between Different Pathways for
Photosynthetic Reductants ............................. 249
5.5 Down-Regulation of Electron Transport Rates ........... 250
5.6 Low-Light Saturation Properties of Photosynthetic
Organisms ............................................. 251
5.7 Photobioreactor and System Costs ...................... 252
5.8 Genomics Approaches ................................... 254
6 Future Directions ......................................... 254
Acknowledgments ........................................... 255
References ................................................ 255
9 Centralized Production of Hydrogen using a Coupled Water
Electrolyzer-Solar Photovoltaic System ...................... 273
James Mason and Ken Zweibel
1 Introduction .............................................. 273
2 Description of a PV Electrolytic H2 Production and
Distribution System ....................................... 274
3 Capital Investment and Levelized Price Estimates .......... 281
4 Sensitivity Analysis: H2 Production and PV Electricity
Prices .................................................... 285
5 Economic Analysis of Second Generation (Year 31-Year 60)
H2 Systems ................................................ 289
6 Life Cycle Energy and GHG Emissions Analyses .............. 294
6.1 Life Cycle Analysis Methods ........................... 294
6.2 Life Cycle Energy and GHG Emissions Analyses
Results ............................................... 296
7 System Energy Flow/Mass/Balance Analysis .................. 296
8 Conclusions: Summary of Results and Suggestions for
Future Analysis ........................................... 298
Appendices ................................................ 305
1 Energy Units and CO2 Equivalent Emissions Estimates ..... 305
2 Levelized Price Estimates Derived by Net Present Value
Cash Flow Analysis ...................................... 305
3 Adiabatic Compression Formula ........................... 307
4 Deviations from DOE H2A Assumptions ..................... 308
5 Summary of Reviewer Comments with Responses ............. 309
References ................................................ 312
Index ......................................................... 315
|
