DeepStor serves the development of high-temperature aquifer thermal energy storage (HT-ATES) in the deep underground. The need for high-temperature heat storage arises from the seasonal fluctuations in heat demand, which often lead to excess heat in summer. By using an extracted hydrocarbon field, the scientists are utilizing the extensive knowledge available for the storage facility and thus creating a genuine geoenergy transition.

Charging and discharging experiments in the potential storage locations on the edge of the former Leopoldshafen oil field enable calibrated investigations of the associated coupled thermal, hydraulic, mechanical and chemical processes in the thermal water cycle. Further fundamental issues relating to the development of this technology will be examined in depth in scientific experiments. In addition to the main focus on heat storage, these include topics such as innovative drilling technologies, two-phase flow, water-rock interactions, the use of nano-tracers and induced seismicity.

With possible further development, the scientific infrastructure could become part of the overall concept for_CO2-neutral heat supply at KIT's North Campus. In the long term, such a concept based on geothermal technologies could serve as a blueprint for surrounding communities and urban areas with heating networks. You can find out more about geothermal energy and geoenergy utilization for the KIT North Campus on the Geoenergy for the Campus subpage.

Development of the research infrastructure

• 2 boreholes to a depth of approx. 1,300 meters
• Test of injection and withdrawal using an above-ground storage basin
• Injection temperature up to 140°C

DeepStor consists of two boreholes at a depth of approx. 1,300 meters and a basin in which the extracted thermal water is temporarily stored until reinjection. The DeepStor-1 exploratory borehole enables investigations in three calcareous sandstone horizons between 800 and 1,300 meters deep, which are to be used for the experiments. In the long term, this borehole will be used for long-term observations. Various sensors will be installed for this purpose.

The DeepStor-2 well enables scientific experiments to be carried out by pumping and reinjecting thermal water. The calcareous sandstone horizons are accessible via a perforation in the casing and are sealed at the top using packers. The deep water extracted during the test phase must be stored temporarily in a storage basin. The storage tests with tempered water up to 140°C are carried out with the aid of a heat exchanger and a mobile heating center.

Measuring probes, which are inserted into the exploratory borehole, record the response of the subsurface to the production and reinjection tests and thus enable long-term monitoring of the tests. In particular, pressure and temperature changes are permanently recorded. In the deepest and backfilled area of the borehole, a seismometer records seismic waves and thus supplements the five seismic surface stations that are set up around the facility. The aim is to record any hydro-mechanical interactions. By continuously recording and processing the measured data in real time , the scientists can combine the data with other results and interpret them to create an overall model of the subsurface.

The Upper Rhine Graben in its current extent from Basel in the south to Frankfurt am Main in the north is a rift valley that reached deep into the earth's crust and was later filled with sediments. Here, the heat balance in the subsurface is determined by a positive temperature anomaly. The Geoenergy & Utilization subpage explains exactly what this is and why this region is so well suited for geoenergy utilization.

The trench fill reaches a thickness of more than 3 km in places and consists of different sediment layers that have been deposited on top of each other over millions of years. These layers are named after the period in the earth's history in which they were deposited, or after a location in which they are found. Their composition gives an indication of the environmental conditions at the time of their deposition. In the Upper Rhine Graben, they bear witness to an eventful history in which this region was characterized by a lake and river landscape and was repeatedly washed over by the sea.

Quaternary & Pliocene, up to max. 200 m, age of deposition: approx. 5 million ^- 12,000 years

The youngest sediments are found here. In the Quaternary and Pliocene, mainly sands and gravels were deposited. They are used as aquifers at KIT Campus North, as in many regions in the Upper Rhine Graben. In order to protect them, the DeepStor borehole in the Pliocene-Quaternary sediments will be isolated from the groundwater-bearing layers by a total of three casings, so that the entry of deep water into the groundwater can be ruled out. In addition, groundwater monitoring with a high temporal and spatial resolution will be installed to monitor groundwater quality.

Landau- /Bruchsal Formation up to approx. 800 meters, Age of deposition: approx. 25 - 16 million years

The Landau formation and the underlying Bruchsal formation are mostly marl, consisting mainly of limestone and clay. The marl layers are interruptedby marine and brackish dolomite and limestone. Fossils such as Corbicula (shell genus) and Cerithia (snail genus) can be found here. The Landau Formation is dominated by marl from freshwater deposits, in which the Hydrobia (snail genus) can be found. In the Landau and Bruchsal formations, there are only isolated sandy layers that could serve as reservoir rocks. At the time of deposition of both formations, there was a high level of tectonic activity.

Niederrödern Formation up to approx. 1000 meters, age of deposition: approx. 28 - 25 million years

The sediments of the Niederrödern Formation are characterized by green, grey, red, ochre ("colourful") marls, into which the first, thicker fluviatile sandstone layers and lenses were deposited in channel systems. The Niederrödern Formation is relatively poor in fossils. A few plant remains and coals occur and indicate continental, fluviatile-lacustrine depositional conditions. During this time the sea had retreated, there were lakes and swamps, and rivers unloaded their cargo.

Froidefontaine formation up to approx. 1400 meters,Age of deposition: approx. 32 - 28 million years

The sediments of the Froidefontaine Formation are characterized by uniform grey marls with intercalated sandstone layers, which were deposited under marine conditions. Fossils are not uncommon and in some cases give the formation its name (e.g. foraminifera marl, fish shale, meletta layers, cyrene marl). The Froidefontaine Formation, like the overlying formation in the area of "oil traps" - as at Leopoldshafen - can be oil-bearing. The salt content in thein the sandstone layers is very high:1 liter of water contains about 120 g of salt. The embedded sandstone layers are to be investigated as possible reservoir rock in DeepStor.

GECKO is an inter- and transdisciplinary joint project between the KIT and the Öko-Institut e.V. In a co-design process, a concept for the use of geothermal energy for a climate-neutral heat supply at the KIT North Campus was developed together with citizens and other stakeholders.
heat supply on the north campus of KIT. The results of this project are being incorporated into the DeepStor concept. In the future, citizens will be invited to collect data themselves as part of a citizen science project and thus gain a direct insight into the research.

Do you have any questions about the project? A collection of FAQs on the subject of geothermal energy and geoenergy use for the campus will soon be available on our website. You are welcome to send your questions to geoenergiecampus∂kit.edu