| Authors |
Rman, Gál, Marcin, Benková, Weilbold, Schubert, Fuks, Rajver, Lapanje, Nádor |
| Abstract |
Historical utilization of regional and transboundary geothermal resources was identified between Austria, Hungary, Slovakia and Slovenia. Its status was determined for the period 2010-2011 and based on a unified methodological approach and field inspections. The assembled data were verified and harmonized in a database with three levels applied: organizational (user’s contact details), formational (hydrogeological data) and object-linked (production characteristics). The web-database is linked to Google maps and available on http://akvamarin.geo-zs.si/users/, while the results and a web-map service are published on http://transenergy-eu.geologie.ac.at/. The research identified 148 active and 65 potential geothermal energy users with 403 geothermal objects spread over the area of 47,700 km2. The 307 active wells produced above 30 million m3 of thermal water in 2009 (no data from Austria is included due to confidentiality reasons). The amount is rising. Among the 11 lithostratigraphical categories of geothermal aquifers, the highest discharge is estimated from the Mesozoic carbonate basement rocks which have transboundary settings in many cases. The Paleozoic carbonates produce water with 109°C in Austria, which is used for electricity production in Bad Blumau together with constant reinjection. Unfortunately, reinjection is not a common practice as only two more periodical reinjection systems are applied in the Mesozoic carbonates in Podhájska (Slovakia) and the Upper Pannonian sands in Lendava (Slovenia). The latter reservoir is regional, cross-cut by the state borders and captured by the majority of abstraction wells in the area, providing thermal water with temperatures up to 91°C. The individual space heating, sanitary water heating, greenhouse or district heating is applied in Slovakia and Slovenia often but drinking and industrial water as well as agricultural use are more common in Hungary. The predominant utilization is still the traditional category - bathing & swimming. The current abstraction has caused overexploitation in some areas, plus the lack of reinjection significantly deteriorates the quantity status of geothermal aquifers and the surface water ecology. The waste water management is often inappropriate, while operational monitoring is not harmonized nor executed sufficiently. The further geothermal development can focus on activation of the inactive boreholes at first, where from the surplus of about 20% of the current thermal water abstraction may be produced. The most promising aquifers are hosted in the Pannonian-Pontian clastic and the Mesozoic carbonate rocks, which may have a transboundary character. Moreover, the concession permits foresee the increase of production for at least twice the current abstraction. The hypothetic thermal water abstraction may rise to over 60 million m3 per year consequently, but it was not investigated during the research whether this is hydrogeologically feasible or which would be the effects on the current and among various users. New geothermal development needs to be based upon: unified and transboundary (where needed) management strategy of exploitation, including best available technologies, harmonized operational monitoring, high thermal energy efficiency, public awareness activities and proper waste water management, including reinjection where possible. This has to be applied as soon as possible among current users also in order to control interference between them and regional impacts on the aquifers status. |