target group: communities, local/regional/national energy agencies
Reliable assessment of geothermal potential is essential for integrating geothermal energy into local and regional energy planning. As geothermal resources depend strongly on geological and hydrogeological conditions, assessment should combine existing data, spatial mapping and, at later stages, site-specific investigation.
Mapping geothermal potentials
As a first step, European-level datasets can provide an initial indication of geothermal potential and identify areas where more detailed assessment may be justified.
A recommended starting point is the European Geological Data Infrastructure (EGDI) Map Viewer, which provides access to the Pan-European Atlas of Sustainable Geo-Energy Capacities and related geothermal datasets. Available layers include favourable areas for deep geothermal prospecting, geothermal wells and thermal springs, as well as information on reservoir depth, temperature and geological characteristics.
For shallow geothermal energy, Hotmaps datasets can provide additional screening information, including ground thermal conductivity, estimated ground temperature and theoretical shallow geothermal potential.
The approach supports the following main objectives:
- Identify areas with favourable geothermal conditions.
- Combine European, national and regional geological data.
- Characterise subsurface temperature and thermal properties.
- Prioritise locations for further investigation.
- Support local and regional energy planning.
Geothermal mapping should provide:
- A spatial overview of geothermal potential.
- Identification of areas suitable for shallow and/or deep geothermal use.
- Better understanding of geological conditions and uncertainties.
- Identification of areas requiring further investigation.
Relevant datasets should preferably be integrated into a geographic information system (GIS) so that geothermal potential can be analysed together with heat demand, district heating infrastructure and land-use constraints.
Geothermal data collection
European-level information should be complemented with more detailed data from national geological surveys, regional databases, existing wells and previous exploration activities.
Relevant information may include:
- Geological and structural data.
- Hydrogeological and aquifer characteristics.
- Borehole and well information.
- Subsurface temperatures and geothermal gradients.
- Thermal conductivity and heat-flow data.
- Geophysical survey data.
- Porosity, permeability and hydrochemical information.
For shallow systems, ground thermal conductivity is particularly important, while for deep geothermal systems reservoir temperature, depth, permeability, flow rate and water chemistry are key parameters.
Assessing geothermal potential
Available datasets should be combined to identify areas with favourable geothermal characteristics. Thermal conductivity can be measured directly or estimated from lithological information and combined with borehole temperatures and geothermal gradients to assess subsurface thermal conditions.
Hydrogeological parameters should also be considered where groundwater contributes to heat transfer. GIS-based analysis can then be used to produce geothermal potential maps and combine them with heat-demand density, district heating networks and relevant spatial constraints.
From potential mapping to project development
Regional geothermal maps are useful screening tools but do not confirm the feasibility of individual projects.
For shallow geothermal systems, further assessment may include detailed geological and hydrogeological analysis and, for larger installations, thermal response testing.
For deep geothermal projects, geological and geophysical investigations are generally required before exploratory drilling. Once wells are drilled, measurements of temperature, flow rate, pressure and hydrochemical characteristics can be used to refine the geological model and quantify recoverable geothermal potential.
During operation, monitoring of system performance and subsurface conditions helps ensure reliable and sustainable use of the geothermal resource.
