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Large transboundary Upper Miocene geothermal sandy aquifers which are widely utilized by both countries for balneological and direct heat purposes exist in the Slovenian-Hungarian border region. In NE Slovenia the total direct heat use was 382 TJ in 2010, while in SW Hungary it was 648 TJ, including utilization from basement reservoirs. The total installed capacity of the 13 Slovenian users was 38.8 MW t , while that of the 29 Hungarian users was 70.6 MW t . Utilisation takes place without harmonized management strategies which might endanger the longterm sustainability of these systems. We aimed to overcome this by delineating a transboundary thermal groundwater body (TTGWB) Mura-Zala with an aerial extent of 4,974 km 2 and with vertical extent between depths 500-2,200 m, which was done based on detailed geological, hydrological, geochemical and geothermal models as well as numerical modelling. The regional groundwater flow in the Mura-Zala TTGWB is from west to east in general, the modeled cross-border flow is approximately 50 l/s. At present, thermal water abstraction rates from the Mura/ Újfalu Fm. (61.8 l/s in the Slovenian and 67.3 l/s in the Hungarian part of the TTGWB) does not endanger the good regional quantity status of the water body, and this should be maintained by allowing a maximum increase of thermal water abstraction 3.5 times higher than today. However, to achieve target numbers for an increased proportion of geothermal energy in the total energy mix in both countries, we suggest that increase of thermal efficiency and re-injection should be prioritized apart from the higher thermal water abstraction with setting up limit of the maximum allowable drawdown. Izvle~ekNa mejnem obmo~ju med Slovenijo in Madžarsko so razprostranjeni obsežni, prekomejni zgornjemiocenski geotermalni pe{~eni vodonosniki, ki se v obeh državah uporabljajo predvsem v balneolo{ke namene in za direktno rabo toplote. V severovzhodni Sloveniji je skupna direktna raba toplote v letu 2010 dosegla 382 TJ, v jugovzhodnem delu Madžarske pa 648 TJ, vklju~no z rabo vodonosnikov v podlagi neogenskih kamnin. Celotna in{talirana kapaciteta 13 slovenskih uporabnikov je zna{ala 38,8 MW t , medtem ko je in{talirana kapaciteta pri 29 madžarskih uporabnikih dosegla 70,6 MW t . Uporaba poteka brez usklajene strategije upravljanja, kar lahko ogrozi dolgoro~no vzdržnost teh sistemov. To smo želeli prese~i z opredelitvijo prekomejnega Mursko-Zalskega telesa termalne podzemne vode (VTPodV Mura-Zala) s povr{ino 4.974 km 2 in vertikalnim razponom globine 500-2200 m, dolo~enega na podlagi podrobnih geolo{kih, hidrogeolo{kih, geokemi~nih in geotermalnih modelov, kot tudi numeri~nega modela podzemne vode. Tok podzemne vode v VTPodV Mura-Zala je usmerjen pretežno v smeri zahod-vzhod, pri ~emer je prekomejni tok ocenjen na približno 50 l/s. Pri trenutni koli~ini odvzema termalne vode (~ 61,8 l/s iz slovenskega ter ~ 67,3 l/s iz madžarskega dela VTPodV Mura-Zala) koli~insko stanje telesa ni ogroženo, a njegovo dobro stanje je potrebno ohranjati ...

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Kratka vsebinaV ~lanku predstavljam pregled osnovnih geotermi~nih definicij in na~el ter pregled osnovne kemijske sestave termalnih in termomineralnih vod v Sloveniji. V Sloveniji je do sedaj znanih 51 geotermalnih lokacij s temperaturo vode na povr{ini nad 20°C, na 18 izmed teh lokacij lahko vodo ozna~imo kot termomineralno. Termalna in termomineralna voda se v Sloveniji uporablja predvsem v balneolo{ke namene (toplice), delno pa tudi za ogrevanje v rastlinjakih in za daljinsko ogrevanje. AbstractIn this paper a short overview of basic geothermal definitions and principles of geothermy is presented as well as a short overview of sources and chemical composition of thermal and thermomineral water in Slovenia. There are 51 geothermal locations in Slovenia with temperature of water (T w ) more than 20°C, whereas 18 of these are considered to be locations with thermomineral waters. The thermal and thermomineral waters in Slovenia are used predominantly in balneology (spas), although thermal water is used for greenhouses and space heating at several locations. Dosedanje raziskaveIzkori{~anje termalnih in termomineralnih vod v zdravili{ke in rekreacijske namene je 'e zelo dolgo pomembna storitvena dejavnost v Sloveniji. Bolj poglobljeno sistemati~no raziskovanje toplic in mineralnih vrelcev se je pri~elo po letu 1969, ko so K u {~a r in sod.

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In this paper we present the results of 3D conductive thermal modeling of the Alpine-Pannonian transition zone. The study area comprises the Vienna, Danube, Styrian and Mura-Zala basins, surrounded by the Eastern Alps, the Western Carpathians and Transdanubian Range. The model consists of three layers: Tertiary sediments, the underlying crust and lithospheric mantle. The crust and mantle were homogenous with constant thermal properties. Heat production in the sediments and crust was 1 lW/m 3. The thermal conductivity of sediments varied horizontally and vertically and based on laboratory measurements. We tested two scenarios: a steady-state and a time-dependent case. The conductive heat transport equation was solved by finite element method using Comsol Multiphysics. The results of the steady-state model fit to the observation in the northern part of the study area, but this model predicts lower heat flow density and temperatures than observed in the southern part of the study area including the Styrian basin. The area underwent lithospheric stretching during the Early-Middle Miocene time, therefore the temperature field in the lithosphere is not steady-state. We calculated the initial temperature distribution in the lithosphere at the end of rifting using non-homogeneous stretching factors, and we modeled the present day thermal field. The results of the time-dependent model fit to the observed heat flow density and temperatures, except in those areas where intensive groundwater flow occurs in the carbonatic basement of the Transdanubian Range and Northern Calcareous Alps, and the metamorphic basement high between the Mura trough and Styrian basin. We conclude that time-dependent model is able to predict the temperature field in the upper 6-8 km of the crust, and is a valuable tool in EGS exploration.

Klju~ne besede: geotermalni visokotemperaturni vir, geotermalna elektrarna, hidrotermalni vir, HDR, EGS, termi~na u~inkovitost, naftna in plinska industrija, severovzhodna Slovenija, Panonski bazen.Key words: high temperature resources, geothermal power plant, hydrothermal resources, HDR, EGS, thermal efficiency, oil and gas industry, Northeastern Slovenia, Pannonian basin Izvle~ek lanek je namenjen ozave{~anju zainteresirane javnosti s ciljem, da lahko vsak presodi resni~nost in pravilnost zapisov, ki se o možnostih izrabe geotermalne energije pojavljajo v medijih. Obravnava namre~ celovit pregled geotermalnih sistemov, potencial hidrotermalnih in izbolj{anih geotermalnih sistemov, nadalje mehanizme in zna~ilnosti srednje-do visokotemperaturnih geotermalnih virov ter na~in njihove pretvorbe v elektriko. Predstavljeni so glavni elementi, ki vplivajo na uspe{nost pretvorbe geotermalne v elektri~no energijo. Podana sta pregled potrebnih raziskav za ugotovitev geotermi~nega potenciala in ocena tehnolo{kih ter ekonomskih možnosti postavitve geotermalnih elektrarn v Sloveniji. Pri tem je opisano stanje poznavanja srednje-in visokotemperaturnih geotermalnih virov v Sloveniji z za~etnimi pogoji za postavitev geotermalne elektrarne. Poleg tega podajamo teoreti~ne izra~une izkoristka pretvorbe geotermalne energije v elektri~no s klasi~nimi turbinami in navajamo pogoste teža-ve pri izkori{~anju geotermalne energije, ki so povezane z dodatnimi stro{ki in znižujejo u~inkovitost investicije. Opisane so lastnosti ter u~inkovitost binarnih geotermalnih elektrarn in tuje izku{nje pri pridobivanju elektrike iz EGS (izbolj{ani geotermalni sistem, angl. Enhanced Geothermal System). Obravnavamo tudi prekrivanje delovanja naftne in plinske industrije z delovanjem EGS ter uporabnost naftnih in plinskih vrtin za proizvodnjo geotermalne elektrike. AbstractThis article is intended to raise awareness of the public, with the aim that anyone can judge reality and accuracy of records that appear in the media on the exploitation of geothermal energy. It provides a comprehensive overview of geothermal systems, potential of hydrothermal and enhanced geothermal systems, of mechanisms and characteristics of middle and high enthalpy geothermal resources. It also deals with a mode of their conversion into electricity. Featured are the main factors affecting the decision on effectiveness of conversion of geothermal energy into electricity. Given are the review of the research necessary to establish the geothermal potential and assessment of technological and economic possibilities of installing geothermal power plants in Slovenia. The paper also describes the state of knowledge of middle-and high temperature geothermal resources in Slovenia with initial conditions for constructing geothermal power plants. In addition, we present theoretical calculations of the conversion efficiency of geothermal energy into electricity with conventional turbines and present some problems for the exploitation of geothermal energy, which are associated with additiona...