DeepStor: Turning a Former Oil Field into a Giant Underground Heat Battery at KIT Campus North
Published by Robert Buluma : | November 2025
Imagine storing the surplus summer heat deep underground and bringing it back up in winter to warm an entire research campus without burning any gas or emitting CO₂. That is exactly what the DeepStor research infrastructure at Karlsruhe Institute of Technology (KIT) Campus North is setting out to prove.
From black gold to green heat
The Upper Rhine Graben, one of Europe’s classic oil provinces, still hides dozens of depleted hydrocarbon reservoirs beneath its surface. Instead of abandoning them, the DeepStor team wants to repurpose one of these former oil fields as a high-temperature seasonal heat storage essentially a gigantic geothermal battery.
Hot water (up to 130–150 °C) would be injected in summer when solar thermal collectors, waste heat from industry or even waste incineration plants produce more heat than needed. In winter, the warm water is pumped back up and the heat is fed into the campus district heating network. If the concept works at demonstration scale, the storage potential in the Karlsruhe region alone is enormous.
The heart of the project: the DeepStor-1 exploratory borehole
To find out whether the geology is really suitable, the scientists are drilling a fully cored research borehole approximately 1,400 metres deep directly on KIT Campus North, right next to the former Leopoldshafen oil field.
What makes DeepStor-1 special:
Continuous coring in the reservoir section → undisturbed rock samples for the laboratory
Comprehensive downhole logging and hydraulic testing
Long-term pressure and temperature monitoring
Intensive seismic monitoring with three different sensor types (geophones, fibre-optic DAS and broadband stations)
Real-time data transmission and public transparency dashboard (under development)
The drilling permit and the main operating plan were officially approved in 2025. Site preparation is already underway, and spud-in of DeepStor-1 is expected in the coming months.
Science meets society the GECKO co-design process
DeepStor is not being developed in an ivory tower. In the accompanying project GECKO (jointly run by KIT and the Öko-Institut e.V.), citizens, local politicians, NGOs and campus users were involved from the very beginning. In workshops and a structured co-design process, a concept for a climate-neutral heat supply of the entire Campus North using geothermal energy and high-temperature storage was developed together.
The result: broad acceptance and concrete suggestions that are now flowing directly into DeepStor planning. In the next phase, interested citizens will even be able to participate in data collection themselves in a citizen-science programme a genuine insight into cutting-edge geoenergy research.
Why this matters ,now more than ever
Germany aims for a complete phase-out of fossil heat by 2045.
Heating and cooling account for more than half of final energy consumption.
heat storage is the missing piece for a 100 % renewable heat supply in regions without large hydropower or biomass potential.
Projects like DeepStor show that the energy transition underground is not a vision of the distant future, but can start tomorrow — sometimes literally in our own backyard.
Want to know more?
Detailed project page (German/English): https://www.deepstor.de
Contact: Dr. Bastian Rudolph & Prof. Dr. Thomas Kohl (KIT Institute for Nuclear Waste Disposal — Geoenergy Division)
Soon online: comprehensive FAQ section and live seismic monitoring data
The former oil field near Karlsruhe could soon become one of the world’s first demonstrated high-temperature aquifer thermal energy storages (HT-ATES) in a depleted hydrocarbon reservoir. DeepStor is turning a relic of the fossil age into a cornerstone of the renewable future.
Stay tuned — the drill bit is about to turn!
KIT – The Research University in the Helmholtz Association
Cover picture: Prof. Dr. Eva Schill
Source: KIT EDU
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