| Abstract |
After some turbulent attempts the local developers & international companies succeed to break the ice and the first geothermal electric power is generated and attributed to the national network (17MWe which can for the moment be passed into the network, up to a potentially 20MWe). That little but crucial step should to raise attention to the understanding and mining of the geothermal energy potential, which is significant for the country needs. That long time expected event, combined with the recent taking over of control of several thousand abandoned hydrocarbon exploration and production wells by the government, together with massive geophysical-geological studies available to investors, will cut costs and risk in the run for the geothermal potential of Croatia. Finally, these efforts will be supported by a new legislative framework for Renewable Energy Sources. These crucial events should rise the interest for new exploration/production licenses, both for power generation and direct heath utilization. In the Croatian south part of Neogen-age “Pannonianian†basins, the main geothermal advantage is the favorable terrestrial heat flow. Heath conduction is easier there because of regional crust thinning less than twenty kilometers and geothermal fluids – predominantly waters convergence through massive structures of Mesozoic fractured carbonate aquifers, insulated with the younger basin fill. In the lover scale they are followed by the basin material origin; carbonate fractured massif and also high profile reservoirs, together with layered sandy bodies, with inter granular porosity, insulated with the fine grained shells, marls and clays. Here, some extraordinary geothermal water bodies at economically reasonable depths from less than 1000 m to hardly over 3000 m can be found, which are able to produce significant outflow from several tens to more than hundred liters / second with temperatures up to hundred to higher than two hundred °C. As most of the already tested fields outflow is artesian, possible enhanced and dry rock geothermal approaches are not disused here. Together with geothermal water production, it is often possible to produce significant quantities of the unconventional hydrocarbon dissolved aquifer gas. Geothermal water production can be used to enhance production in aged hydrocarbon fields. Other geothermal energy targets are numerous poorly developed natural geothermal springs and shallow (500 - more than 1000 m) “geo-temperate waters†structures are also attractive for low cost / low energy gain - recreation & balneology, where some of them can rise up to worthy energy production, not mentioning standard procedures to pump the energy from neutral earth layer by heat pump technology and hybrid energy systems. Beside proved geothermal potential of the north Croatian Pannonian sedimentary basin, geothermal potential is expected also at the tectonically active belt of the Dinara carbonate platform range stretching to southwest. It is marked by some natural geothermal springs and shows, but its potential will be revealed by the better understanding of hydrocarbon games & fields, together with expected deep geothermal water. Now after “geothermal power†is running through the Croatian electric network, conservative expectation from the proven part of geothermal potential posted at the beginning of the century (conservatively let say 10 % total potential) saying that a stable electric power generation can reach 100 MWe (2% of the existing capacity in the country) followed by several hundred MWt, as co-generation in direct used heat, together with 500 MWt direct geothermal heat consumption (10 % total?) or 1/4 of nowadays natural gas consumption (as the main fuel for the moment), from drilling at new sites and/or using several hundred abandoned oil & gas deep wells. Already, such conservative predictions of geothermal energy production can change the lethargic visions of the energy mix of the country into to the self-sustaining domestic clean and stable energy supply, and make the country meaningful in the EU & world economy. The geothermal energy resources are a trigger to the complex development of Croatia for all who come and stay in the country. |