The Danish subsurface contains large geothermal resources. However, it is associated with high risk to establish a geothermal plant, if the geology in subsurface is not known at the locality where the plant is expected to be constructed.

The portal presents a number of geological map themes, relevant for geothermal energy, so stakeholders in the geothermal industry as well as the authorities can form an overview over the nature of the subsurface, geological uncertainty and density and quality of geological data within the Danish onshore and near coast area. The focus is on geothermal sandstone reservoirs located within the depth zone of 800-3000 meters below mean sea level. The portal and the underlying analyses of data and map themes have been prepared for funds as set out in the Energy Policy Agreement of 22 March 2012. Furthermore, data and results are included in a geothermal research project conducted under the auspices of the Danish Council for Strategic Research.

The most important geological data that provide information about Denmark’s deep subsurface are data from deep wells and seismic surveys, mainly collected in connection with oil-gas exploration activities. The geological data is collected, quality assured, analysed and used to produce the maps included in the portal. Behind the design of the maps are several elements of generalizations and approximations, and the maps should therefore only be considered as indicative and for use on a regional scale.

The maps provide a good basis for making a competent and more specific geological assessment of the geothermal potential of a concrete site where a geothermal plant is desired. However, in such an assessment, the nearest data from deep wells and seismic surveys should be included in the analysis of the site rather than if only the interpreted nationwide map themes in the portal are used. Such an analysis corresponds approximately to the screening carried out by 28 localities as part of the above Energy Policy Agreement, and located near district heating areas, and whose results are available from the portal.