Chapter 4 - Geothermal systems and resources

Abstract

This chapter introduces the geothermal systems and resources. A geothermal resource can be defined as a reservoir inside the Earth from which heat can be extracted economically (cost wise less expensive than or comparable with other conventional sources of energy—such as hydroelectric power or fossil fuels) and utilized for generating electric power or any other suitable industrial, agricultural or domestic application in the near future. A geothermal reservoir contains heat both in the solid rock as well as in the fluids that fill the fractures and pore spaces within the rock. Estimation of geothermal resources is made on the basis of various geological and geophysical data. A geothermal resource is distinct from a geothermal reserve, which refers to the part of a resource that can be extracted economically at the present price level. The chapter also identifies the types of geothermal systems. Reserves are confirmed on the basis of detailed reservoir datasets obtained by deep drilling into potential resource areas. Therefore, the main factors in estimating reserves are the cost of drilling and the quality of available data on subsurface rock formations.