World Aquifer Viewer

Welcome to ThermoGIS World Edition: a global geographical information system for assessing the at a glance geothermal energy potential from sedimentary aquifers for low enthalpy applications (ca. 40-150°C).

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This online tool has been developed by TNO, ISES (the Netherlands), BRGM (France), GFZ (Germany), CNR-IGG (Italy), CEGL (Italy) and LIAG (Germany) in the framework of the 'Joint Programme on Geothermal Energy' of the Europese Energy Research Alliance (EERA).

ThermoGIS World Edition is based on a newly compiled map of global heat flow which controls the geothermal gradient, and on a newly compiled global map of sedimentary basins controlling the lateral and vertical extent of aquifers. ThermoGIS World Edition presents various derived maps. One is the expected maximum production temperatures up to 3 km depth. These maps were extrapolated based on the geothermal gradient and average surface temperatures from NASA. Minimum drilling depths to reach sufficiently high production temperatures for various direct heat use applications have been calculated. Further, theoretical and technical potential maps have been produced based on an overall performance assessment indicator and minimum drilling depth.

The tool is intended to provide a global overview for the direct use heat potential and should not be used for a local potential assessment. We are aware of limitations in the underlying datasets. The geothermal expert community worldwide is invited to contribute to improvement of the maps. When more detailed data becomes available, they will be incorporated in the present dataset to create a more accurate tool.


How the viewer works

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Methodology

Geothermal heat can be produced from sedimentary aquifers when natural permeability is sufficiently high to produce hot water from wells without stimulation. Aquifers are present in sedimentary basins covering large areas of the World. Temperatures in aquifers increase with depth in accordance with the geothermal gradient which ranges from approximately 10 to 100°C km-1. Up to 3 km depth, aquifers can be sufficiently permeable to produce hot water from a well. At the surface the energy of the produced water is extracted by a heat exchanger. After cooling the water is re-injected in another well in the same aquifer to provide pressure support for the production and to avoid contamination of the surface environment. This closed loop production system is called a geothermal doublet. As heat cannot be transported over large distances, the applicability is generally limited to populated and agricultural areas. In the future this may change when low enthalpy heat can be used to generate electricity.

Figure: Flow diagram of the map construction methodology


Different Applications

The applicability of geothermal energy is dependent on the average surface temperature (T0). For example, at average surface temperatures above 15°C, the application of geothermal energy for cooling is more useful than the application for greenhouse heating. The geothermal potential maps have a different appearance depending on the requirements for production and re-injection temperatures for each application. For the application of geothermal energy for greenhouse heating, spatial heating and cooling, boundary conditions are defined for both the surface (minimum and maximum surface temperature) and the subsurface (minimum production temperature en re-injection temperature). These boundary conditions are summarized in the table below:

Application Minimum T0 Maximum T0Min. Production TemperatureRe-injection Temperature
Greenhouse Heating -15°C15°C45°C25°C
Spatial Heating -15°C15°C70°C40°C
Spatial Cooling 15°C70°C35°C
Generalized Tsurface + 40°CTsurface + 10°C

Limitations of ThermoGIS World Edition and an invitation to contribute

The tool is intended to provide a global overview for the direct use of heat potential and should not be used for more local potential assessments. We are aware of limitations in the underlying datasets, which are described under the subsections of the individual maps.

The source maps have been compiled world coordinates (longitude & latitude) with a resolution of 15 minutes or 0.25 degrees. This global compilation can benefit considerably from the contributions of new datasets and user comments. When more detailed data becomes available, they will be incorporated in the present dataset to create a more accurate information tool. We invite the global geothermal community worldwide to submit comments to improve the maps and supply us with digital datasets, if available. Please send us an e-mail to us, it is much appreciated!


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