chapter 1. Introduction -- chapter 2. Sources of geothermal heat : the earth as a heat engine -- chapter 3. Thermodynamics and geothermal systems -- chapter 4. Subsurface fluid flow : hydrology of geothermal systems -- chapter 5. Chemistry of geothermal fluids -- chapter 6. Exploring for geothermal systems : geology and geochemistry -- chapter 7. Exploring for geothermal systems : geophysical methods -- chapter 8. Resource assessments -- chapter 9. Drilling -- chapter 10. Generating power using geothermal resources -- chapter 11. Low-temperature geothermal resources : geothermal heat pumps -- chapter 12. Direct use of geothermal resources -- chapter 13. Enhanced geothermal systems -- chapter 14. Use of geothermal resources : economic considerations -- chapter 15. Use of geothermal resources : environmental considerations -- chapter 16. Geothermal energy future : possibilities and issues.