Page 9 - Geothermal Energy Renewable Energy and The Environment

viii Contents

Confining Pressure and Rock Strength ............................................................... 141
Temperature and Drilling Fluid Stability ............................................................ 143
Casing and Grouting ............................................................................................ 145
Packers ................................................................................................................. 146
Lost Circulation ................................................................................................... 147
Directional Drilling ............................................................................................. 147
Case Study: Kakkonda, Japan .................................................................................. 149
Synopsis .................................................................................................................... 151
References ................................................................................................................ 151
Further Information .................................................................................................. 152

Chapter 9. Generating Power Using Geothermal Resources ..................................................... 153
The History of Geothermal Power Production ........................................................ 153
General Features of Geothermal Power Generation Facilities ................................154
Dry Steam Resources ............................................................................................... 155
Hydrothermal Systems ............................................................................................. 161
Flashing ............................................................................................................... 163
Steam Quality ...................................................................................................... 165
Dual-Flash Systems ............................................................................................. 166
The End State: Condensers and Cooling Towers ................................................ 167
Binary Generation Facilities: The Organic Rankine Cycle ..................................... 168
Case Study: The Geysers .......................................................................................... 170
Geology ............................................................................................................... 170
Power Generation History ................................................................................... 172
Emissions ............................................................................................................. 172
Sustainability and Reinjection ............................................................................. 173
Synopsis .................................................................................................................... 176
References ................................................................................................................ 177
Further Information .................................................................................................. 178

Chapter 10. Low Temperature Geothermal Resources: Ground Source Heat Pumps ................ 183
Basic Heat Pump Principles ..................................................................................... 183
Thermodynamics of Heat Pumps ............................................................................. 186
Coefficient of Performance (COP) and Energy Efficiency Ratio (EER) ............. 187
Near-Surface Thermal Reservoir ............................................................................. 187
Solar Insolation .................................................................................................... 188
Soil Characteristics .............................................................................................. 188
Thermal Conductivity and Heat Capacity of Soils ..............................................190
Design Considerations for Closed-Loop Systems .................................................... 191
Heating and Cooling Loads ................................................................................. 191
Calculating Loop Length ..................................................................................... 191
Case Study: Weaverville .......................................................................................... 193
Synopsis .................................................................................................................... 198
References ................................................................................................................199
Further Information ..................................................................................................199

Chapter 11 Direct Use of Geothermal Resources .......................................................................201
Assessing the Magnitude of the Direct Use Reservoir ............................................201
The Nature of Thermal Energy Transfer..................................................................203