| Abstract |
Geothermal research and development in Bosnia and Herzegovina was initiated after World war II. Geothermal energy was used from hydrogeothermal systems only. The degree of research and utilization of geothermal energy was the greatest in period 1980 – 1992 and the smallest during the war 1992-95 in B&H. After 2005 it is evident slow increase of geothermal use comparing to period 1995-2005. Geotectonic zones in Bosnia and Herzegovina are the following: 1) Sava-Vardar Zone (Active continental margin); 2) The Dinaride Ophiolite Zone; 3) The Bosnian Flysch Zone (Passive continental margin); 4) Allochtonous Paleozoic and Triassic formations from Mid-Bosnian Schist Mountains, Una – Sana Nappe, Durmitor Nappe and 5) Dinaric carbonate platform. A greater number of geothermal energy deposits of low enthalpy are encountered in Bosnia and Herzegovina in all geotectonic zones except zone 5). There are 9 hydrogeothermal regions in Bosnia and Herzegovina. According to boreholes data in hydrogeothermal regions 1, 2, 3, 4, 5, 6 and 7 conductive geothermal gradients vary from G=28,2 - 49,6°C/km and heat flow values q = 60 – 88,7mW/m2. Convective maximal values are G=66,6°C/km and q=134,9 mW/m2 in Active continental margin, more less values are in Passive continental margin and Mid- Bosnian Schist Mountains. The smallest values are in Dinaric carbonate platform (drillhole Gla-1, 4,206 m depth - G=10,9 mK/m and q=38,2 mW/m2).The highest measured temperatures are in Active continental margin (hydrogeothermal region 2) vary from 39-62°C at 1000 m, 78 – 101°C at 2000 m, 111 – 147°C at 3000 m and 176 – 209 °C at 5000 m below surface. Significantly lower values of gradients and heat flows are in Dinaric carbonate platform 10- 20°C/km and 20-50 mW/m2. The extreme lower temperature values (25-38°C at 1000 m) are supposed in Dinaric carbonate platform on the basis of only one drill hole in Bosnia and Herzegovina and ten drill holes in adjacent areas of Croatia and Montenegro. The largest positive geothermal anomalies are in the Pannonian Basin (Active continental margin); minor potential is in area of Allochtonous Paleozoic and Triassic formations and practically without geothermal potentials in Outer Dinarides (Dinaric carbonate platform). The main geothermal lower reservoirs in Pannonian Basin are situated in Middle and Upper Triassic and upper reservoirs of minor enthalpy are in Cretaceous and Tertiary marine sediments. Triassic aquifers occur deeper of 1500 m below surface of terrain. Thickness of Triassic reservoirs is supposed 500-800 m and its area is about 6500 km2. Numerous separate reservoirs of minor geothermal potentials are in Dinaric Ophiolite Zone, The Bosnian Flysch Zone, Allochtonous Paleozoic and Triassic formations from Mid-Bosnian Schist Mountains with main reservoirs in Triassic carbonate rocks. Direct use of geothermal energy is mainly attributed to bathing and swimming (including balneology), space heating, less for geothermal heat pumps, greenhouses and industrial use. There are 22 thermal and thermomineral spas and recreations centers where swimming pools are heated by geothermal water directly or indirectly through heat exchangers and GHPs. Thermal spas and recreations centers are predominant thermal localities for direct heat use. At 3 thermal spas geothermal heat pumps are included, whereas the utilization included in 31 deposits only with total available power ca 200 MWt with referent temperature of 10 °C. As the temperature outputs are far higher than 10, the real power utilization is much lower. During the last 8 years exploration and development have resulted in only 8 new wells with a total depth of about 3,5 km. One of them well GD-2-Slobomir in Semberija encountered water temperatures of 73°C, Qpump.=45 l/s and depth 1,800 m and other in Slatina near Banja Luka in Ophiolite Zone has t= 44°C; both wells drilled waters in Triassic limestones. It is planned exploration and use of hydrogeothermal potentials in area of town Bijeljina in Triassic limestones (Pannonian Basin), which includes drilling 5 wells of single depth of 2500 m with water temperature t=130°C for district heating. |