Achieving sustainable exploitation of thermal aquifers based on good governance is a recurrent challenge faced globally. The Pannonian Basin is a clear example, where some neighbouring countries have delineated thermal groundwater bodies, which must be assessed and managed according to the EU Water Framework Directive. In most cases these thermal aquifers are transboundary, necessitating the use of common assessment methodologies, monitoring requirements, and data sharing. As the economies of these countries develop, with growing demands from competing sectors, the need for both cold groundwater and thermal water increases. Boosting the share of renewables within the energy sector generally results in increased groundwater abstraction. This has a negative impact in the transboundary zones where aquifers cross national boundaries.
The international projects T-JAM and Transenergy assessed transboundary thermal aquifers in the Pannonian Basin, proposing improved management goals. The ongoing DARLINGe project promotes a more sustainable, governance-based exploitation of existing geothermal resources in the heating sector which will contribute to an improved energy efficiency and security in the Danube Region.
An innovative benchmarking methodology, developed and refined within this project, provides an easily comparable, informative tool for thermal water management, and its use supports measures for more efficient energy production. The tool has been tested and evaluated in selected transboundary thermal aquifers of the Pannonian Basin using a unified and harmonised approach. Pilot sites were investigated in the Hungarian-Serbian-Romanian, Slovenian-Croatian-Hungarian and Serbian-Bosnia-Herzegovinian transboundary thermal aquifers.
Five main stakeholder groups each with different interests can benefit from this methodology. These are: 1) management authorities, international organizations, 2) licencing authorities, 3) research organizations and universities, 4) investors in geothermal use, and 5) thermal water users. Following the identification of potential beneficiaries ten relevant criteria of the benchmarking methodology were defined.
Five categories of benchmarking indicators are defined: 1) management, 2) technology and energy, 3) environment, 4) social, and 5) economic. The minimum data requirements and data evaluation level is specified for each indicator. The indicators related to management are: licencing procedure, monitoring requirements, monitoring setup and passive monitoring. The indicators related to technology and energy use are: operational issues, cascade use, thermal efficiency, and utilisation efficiency. Environmental issues deal with reinjection, over-exploitation, and the status of water balance indicators. Waste water management evaluation could not be applied in all partner countries due to a lack of current availability of recent monitoring data. The social indicator was tested based on public awareness at site level. An example of an economic indicator is shown on a project level.
For ease of use the tool calculates a final benchmarking number based on indicator types and values.