engleski

Basic geothermal characteristics of Croatia and use of geothermal energy in Croatia

The Republic of Croatia can be divided generally into two geologically different regions. In its southeastern part which belongs to the Dinaride area, the Mesozoic carbonate rocks prevail. Due northeast, in the area belonging to the Pannonian Basin, the Quaternary and Tertiary sedimentary rocks dominate which overly the crystalline bedrock and occasional Mesozoic sedimentary rocks. According to previous investigations, Croatia is endowed with significant geothermal potential in the Pannonian area. The temperature gradient in this region ranges from 0, 03 to 0, 07 0C/m which is more than the world mean value. The terrestrial heat-flow density is also high, ranging from 60 to 100 mWm3 (Jelić et al., 1995), and occasionally up to 120 mWm3 (Kovačić, 1995). In Croatia, as much as 30 springs of the thermal water exist with temperature ranging from 17 to 65 0C. In the Pannonian region more than 50 deep boreholes have been drilled through the geothermal aquifers in which temperature ranges from 40 to 170 0C (Kovačić & Perica, 1998). Figure 1. displays the geothermal regions (Kovačić, 2001). For some of these, the geothermal fields have been defined, but the majority still requires further investigations. Most of the geothermal areas abound with boreholes drilled through the geothermal aquifers, but their thermal waters are still of no application. Table 1. displays the fundamental data on the objects from where the geothermal water is currently in use. In Croatia, over 76 locations of geothermal water are known having temperature over 200C, among which are 26 geothermal springs and over 50 deep boreholes. Due to their characteristics these waters are suitable for different purposes (Kovačić & Jelić 1999). The data analyses confirm that geothermal water is used only from 24 locations, which is less than 31 % of all identified locations. In some of them the geothermal water is used for more than one purpose. However, in some locations the use of geothermal water for greenhouse and soil heating in vegetable production has been abandoned because of inadequate technology and outdated equipment. Thus, geothermal water in Croatia is mainly used in less demanding modes, while some of technologically more demanding modes of utilization have not been examined (Kovačić, 2000). The fact is that a small portion of known geothermal energy potential in Croatia is currently under application, but due to incomplete geothermal reconnaissance of the area, detection of new geothermal capacities can be expected.

geothermal energy; heat-flow density

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