Deutsche Version  ACT
Overarching Themes
Performance Potential 1.4.2016

The figure shows a H2 storage cavern (green) and a compressed air cavern (blue).

Forecasting the potential of caverns

What potential is there for energy storage in the salt structures of Northern Germany? This question is being addressed by researchers in the InSpEE project. They are investigated the planning bases and selection criteria for constructing salt cavern storage facilities. The researchers are also investigated how much compressed air and hydrogen can be stored in these.

Project status Project has finished
Project duration May 2012 until September 2015

The focus of this project was the establishment of the necessary bases for an assessment of the potential of North German salt structures, in terms of the storage of compressed air and hydrogen in salt caverns, and the development of a methodology for the assessment itself.  A particular value of this project was the creation of a “Salt” information system, in which publicly available information on the individual salt structures were compiled, edited and linked.

Storage power plants with underground storage for compressed air or hydrogen are one of the few options for large-scale energy storage; however the only estimates of the total potential are insufficiently substantiated. This initial situation formed the starting point for this project, firstly, to establish a necessary foundation and secondly, to apply them in the form of an assessment of the storage potential of the salt structures in the North German Basin.  In this case, the processing was carried out by the following project partners: Federal Institute for Geosciences and Natural Resources (BGR), Leibniz University of Hanover, Institute of Geotechnical Engineering / Department of Underground Construction (IGtH) and KBB Underground Technologies GmbH (KBB UT). These project partners are working in cooperation, bringing together their existing expertise in the areas of salt geology and rock mechanics, with a focus on rock salt and the planning and construction of salt cavern storage. At the end of the over three-year project period, a publicly accessible “Salt” information system is provided and in addition, a storage potential for CAES and hydrogen in Northern Germany is named.

  • Classification of the salt structures
  • Salt structures in northern Germany © BGR
  • Anticipated internal structure in a 3D model of a salt dome for the planning of further cavern wells © KBB UT
  • Identification of potential number and arrangement of caverns in a structure © KBB UT

Establish foundations

The accelerated transition to fluctuating renewable energy sources raises the question of large-scale electrical energy storage.  Energy storage power plants which generate, feed and withdraw renewable electricity from compressed air and heat or hydrogen on demand play an essential role.  Large-volume storage of these media can only be accommodated in the geological substratum. A high degree of flexibility in operation and a low proportion of cushion gas, as well as an extremely low tendency to react with the stored commodity, make salt storage caverns the preferred storage option. To date, no basis has been adopted for the evaluation and conduct of a substantiated assessment of different storage locations in which energy can be stored in the geological substratum. The objectives of the project were, therefore, the development and deployment of design principles and basic geological/geotechnical data and of site selection criteria for the establishment of salt caverns as well as the estimation of the renewable energy storage potentials of the North German salt structures.

Three thematic focal points

The project was divided into the following thematic focal points: 1) the establishment of design principles, 2) the creation of a set of criteria, and 3) the application of the results in the form of an assessment of potential. The project was completed in September 2015. The report has been published and the information system "Salt" can be viewed on this link.

In October 2015 the follow up project “InSpEE-DS” has started. This project proposes to develop and prepare the planning fundamentals required in order to select locations and construct salt caverns for the storage of renewable energies in the form of hydrogen and compressed air energy storages multi-salt-formations as well as bedded salt structured in Germany. The project follows on from the InSpEE project, the scope of which was limited to considering thicker Zechstein salt structures in North Germany. The InSpEE-DS project  seeks to develop the requirements and criteria on the basis of which suitability assessments are also possible of shallower salt formations and multiple or double salt formations for storage projects during a relatively early stage of site exploration, i. e. despite having only relatively limited knowledge of the internal structure of the salt formations.”


As part of the project work, a knowledge base was created, whose potential optimization will not be carried out within the project period. Nevertheless, the results of the study can be used both for a targeted selection of storage sites and for an assessment of the technical feasibility of storing large amounts of energy.  Therefore, beyond the scope of this project, it will also offer the potential for optimizing other projects and studies having a focus on energy storage.

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


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Research funding

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