The internal heat of the planet Earth represents an inexhaustible reservoir of thermal energy. This form of energy, known as geothermal energy has been utilized throughout human history in the form of hot water from hot springs. Modern utilization of geothermal energy includes direct use of the heat and its conversion to other forms of energy, mainly electricity. Geothermal energy is a form of renewable energy and its use is associated with very little or no CO2-emissions and its importance as an energy source has greatly increased as the effects of climate change become more prominent. Because of its inexhaustibility it is obvious that utilization of geothermal energy will become a cornerstone of future energy supplies.
The exploration of geothermal resources has become an important topic of study as geology and earth science students prepare to meet the demands of a rapidly growing industry, which involves an increasing number professionals and public institutions participating in geothermal energy related projects. Geothermal Energy meets the demands of both groups of readers, students and professionals. Geothermal energy and its utilization is systematically presented and contains the necessary technical information needed for developing and understanding geothermal energy projects. It presents basic knowledge on the Earth's thermal regime and its geothermal energy resources, the types of geothermal energy used as well as its future potential and the perspectives of the industry. Specific chapters of Geothermal Energy deal with borehole heat exchangers and with the direct use of groundwater and thermal water in hydrogeothermal systems. A central topic are Enhanced Geothermal Systems (hot-dry-rock systems), a key technology for energy supply in the near future. Pre-drilling site investigations, drilling technology, well logging and hydraulic test programs are important subjects related to the exploration phase of developing geothermal energy sites. The chemical composition of the natural waters used as a heat transport medium in geothermal systems can be used as an exploration tool, but chemistry is also important during operation of a geothermal power plant because of potential scale formation and corrosion of pipes and installations, which needs to be prevented. Graduate students and professionals will find in depth information on geothermal energy, its exploration and utilization.
1. Thermal Structure of the Earth
1.1 Renewable Energies, Global Aspects
1.2 Internal Structure of the Earth
1.3 Energy budget of the planet
1.4 Heat transport and thermal parameters
1.5 Brief outline of methods for measuring thermal parameters
2. History of Geothermal Energy Use
2.1 Early utilization of geothermal energy
2.2 History of Utilization of Geothermal Energy in the last 150 Years
3. Geothermal Energy Resources
3.1 Energy
3.2 Significance of "renewable" energies
3.3 Status of geothermal energy utilization
3.4 Geothermal energy sources
4. Application of Geothermal Energy
4.1 Near surface Geothermal Systems
4.2 Deep Geothermal Systems
4.3 Efficiency of geothermal systems
4.4 Major geothermal fields, high enthalpy fields
5. Potentials and Perspectives of Geothermal Utilization
6. Geothermal Probes
6.1 Planning Principles
6.2 Construction of ground source heat exchangers
6.3 Dimensioning and design of geothermal probes
6.4 Drilling methods for borehole heat exchanger
6.5 Backfill and grouting of geothermal probes
6.6 Construction of deep geothermal probes
6.7 Operating geothermal probes: Potential risks, malfunctions and damages
6.8 Special systems and further developments
7. Geothermal Well Systems
7.1 Building geothermal well systems
7.2 Chemical aspects of two-well systems
7.3 Thermal range of influence, numerical models
8. Hydrothermal Systems, Geothermal Doublets
8.1 Geology and tectonic structure of the underground
8.2 Thermal and hydraulic properties of the target aquifer
8.3 Hydraulic and thermal range of hydrothermal doublets
8.4 Hydrochemistry of hot waters from great depth
8.5 Reservoir-improving measures, Efficiency-boosting measures, Stimulation
8.6 Productivity risk, Exploration risk, Economic efficiency
8.7 Some site examples of hydrothermal systems
8.8 Project planning of hydrothermal power systems
9. Enhanced-Geothermal-Systems (EGS), Hot-Dry-Rock Systems (HDR), Deep-Heat-Mining (DHM)
9.1 Techniques, procedures, strategies, aims
9.2 Historical development of the hydraulic fracturing technology, early HDR sites
9.3 Stimulation procedures
9.4 Experience and dealing with micro-seismicity
9.5 Recommendations, Notes
10.Environmental Issues Related to Deep Geothermal Systems
10.1 Seismicity related to EGS projects
10.2 Interaction between geothermal system operation and the subsurface
10.3 Environmental issues related to surface installations and operation
11. Drilling techniques for deep wellbores
12. Geophysical methods, exploration and analysis
12.1 Geophysical pre-drilling exploration, seismic investigations
12.2 Geophysical well logging and data interpretation
13.Testing the hydraulic properties of the drilled formations
13.1 Principles of hydraulic testing
13.2 Types of tests, planning and implementation, evaluation procedures
13.3 Tracer Experiments
13.4 Temperature evaluation methods
14. The chemical composition of deep geothermal waters and its consequences for planning and operating a geothermal power plant
14.1 Sampling and laboratory analyses
14.2 Deep geothermal waters, data and interpretation
14.3 Mineral scales and materials corrosion
15. References
Ingrid Stober studied Earth Sciences at the University of Freiburg (Germany). 1985 Ph.D. with the dissertation on "groundwater flow patterns in hard-rock aquifers, results from pumping- and injection-tests". 1994 habilitation thesis on "hydrogeology of crystalline rocks of the Black Forest, Germany". She is working at the Geological Survey of Baden-Württemberg, with the responsibility for geothermal energy. Her research interests are geothermal waters and hydraulics.
Kurt Bucher studied Geology at ETH Zurich (Switzerland). 1977 Ph.D. in metamorphic petrology. Assistant professor at the University of Basel (Switzerland), Professor of Geology at the University of Oslo (Norway) and is currently Full Professor of Mineralogy and Geochemistry at the University of Freiburg (Germany). His research is focused on field studies of water-rock interaction processes in deep geothermal systems.