Deutsche Version  ACT
Thermal Storage
Long-term storage 9.1.2017

Simplified functional scheme of an aquifer storage during charging (left) and discharging (right).
© Deutsches GeoForschungsZentrum (GFZ)

Saisonal storage in aquifers

Aquifers have a large storage capacity and offer considerable potential

as seasonal thermal or cooling storage systems. In a research project,

researchers developed an improved storage concept for supplying heating

and cooling energy to buildings and entire urban districts. For this

purpose, they are combined the expertise from various specialist areas

such as energy technology, geochemistry, hydrogeology, architecture and

urban development.

Project status Project completed
Temperature type Low temperature
Storage type Sensible heat storage
Storage medium Ground water and rocks
Storage/Charging Direct
Storage time Long (seasonal)
Number of cycles No restriction
Charging temperature 5 - 90°C
Discharge temperature 5 - 90°C
Storage capacity 180 TJ
Energy storage density 2,5MJ/m³/K
Project duration December 2012 until November 2016

Realising improvements

The technical feasibilty of energy supply systems with aquifer storages has already been demonstrated at three German sites (Berlin Parliament Buildings, Rostock and Neubrandenburg). Despite the large demand on energy storages and the widely spread potential of aquifer storages a broader market introduction of aquifer storages is still hindered. The greater aim of this research project refers to the development of site-independent design concepts in order to increase reliability and efficiency of aquifer thermal storages and to contribute to the further deployment of this technology. Within this context, the reliable integration of aquifers, the improvement of the necessary plant technology for heat transformation as well as the efficiency increase of the overall system are of central interest.

  • Comparison of modeled temperatures calculated (symbols) and measured temperatures (lines) for the hot and cold bore of an aquifer storage © Deutsches GeoForschungsZentrum (GFZ)
  • Simplified functional scheme of an aquifer storage during charging (left) and discharging (right). © Deutsches GeoForschungsZentrum (GFZ)

Understanding interactions

Energy supply systems utilizting aquifer storages consist of different sub-systems that involve different technical characteristics and requirements. Thereby it is especially important to know the interaction between the subsurface, including the heat carrier groundwater, the surface plant technology and the energy customers. Due to the mutual influence and the feedback between these sub-systems, improvements can only be realized by means of a holistic system evaluation.

Analysis and experimental investigations

Subsurface and application oriented storage configurations which meet the requirements of operational reliability and guarantee the energetically optimized integration of aquifer storages into the energy supply system are developed. The development of energy supply concepts will be realized by coupling different modeling and simulation tools with the results from laboratory experiments as well as experiences from already operated aquifer storages. 

The aquifer properties and the mass transport within the aquifer are characterized for the variable conditions that occur in a thermal, siliciclastic aquifer during operation in order to identify the potentially induced permeability changes. The characterisation will be based on laboratory and field experiments.

A flexible plant configuration will be developed that meets the requirements of both, the aquifer storage and the energy customers. In addition to the development of system models for the energy conversion also theoretical and experimental investigation on a test heat transformator will be carried out. 

A simplified city quarter system model will be developed in order to analyse the adaptability of different types of buildings to the energy supply from systems with aquifer storage, heat pumps and heat transfomers. The possibility to use solar energy from  roof, façade and open space systems will also be considered. The developed model will serve for design and specification of the energy supply system and will be used to identify further optimisation potential. 

Project status

In the beginning of 2013 the characterisation of the subsurface at the TU Berlin Campus has started and a first assessment of the storage integration as well as the overall system has been carried out. The definition of technical requirements and desing specifications of the energy conversion/supply equipment is an ongoing activity. Additionally, the interfaces between aquifer storage and surface plant technology and energy customers for modelling and simulation as well as technical realisation are under elaboration. The simulation and technical implementation will be accompanied by laboratory experiments on fluid-rock-interactions for different temperatures which are prepared at the moment.

Supported by: The Federal Government on the basis of a decision by the German Bundestag


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  • Dr. Ali Saadat
    Helmholtz-Zentrum Potsdam Deutsches GeoForschungsZentrum GFZ International Centre for Geothermal Research ICGR Sektion 6.2 Geothermische Energiesysteme
Other Addresses


Research funding

The information system EnArgus provides information on research funding, including on this project (German only).