UTES Symposium in Offenburg 2024

Storage is key!

The GEOTHERMICA Initiative , IEA Geothermal and IEA Energy Storage TCP jointly organised a symposium on underground thermal energy storage (UTES) in conjunction with the GeoTHERM conference in Offenburg on 28 February. The aim of the event was to foster international collaboration and networking among researchers, industry experts, and public authorities to advance UTES-related discussions.

Speakers introduces UTES in various forms, including aquifer storage systems (ATES), borehole thermal energy storage (BTES), mine water thermal energy storage (MTES), and pit thermal energy storage (PTES). Discussions focused on opportunities, challenges, and the future prospects of energy storage.

Over 130 people attended from 16 countries (Austria, Algeria, Belgium, Denmark, Germany, France, Iceland, Italy, the Netherlands, New Zealand, Saudi Arabia, Spain, Sweden, Switzerland, Turkey, and the United Kingdom), that represented research, industry, and the public sector. 

Key takeaways from the discussions include:

  • Potential is huge for heat networks.
  • Storage is key for the energy transition – for utilising renewable energy sources for heating, including solar power.
  • Knowledge exchange is crucial – there is need to collaborate more internationally, to learn from successful projects.
  • Raising awareness outside of the geothermal community is important – the sector should communicate a joint message on the benefits of heat storage.
  • Capacity building is needed in the sector – many regions lack practical expertise and know-how.
  • Policy and regulatory environments need to support the sector – regulations are often unclear, and sometimes non-existent for UTES, and approval processes are sometimes slow.
  • Data and research are often scarce in the sector.
  • Mitigation plans need to be in place to deal with potential negative impact.
  • Funding of UTES projects can be difficult – funding schemes are often complex or not suitable.


- Christian Minnig (IEA Geothermal TCP, CH) IEA Geothermal TCP PDF presentation
- Paul Ramsak (GEOTHERMICA Initiative, NL) GEOTHERMICA Initiative PDF presentation
- Stan van den Broek (IEA Energy Storage, NL) IEA Energy Storage TCP PDF presentation

Introduction to Large-scale UTES

- Robin Horsmans (GEOTHERMICA Initiative, NL) Large-scale UTES PDF presentation

ATES overview presentations

- Sebastian Bauer (Uni Kiel, DE) ATES Overview PDF presentation

- Bas Godschalk (IF Technology, NL) ATES Overview  PDF presentation

ATES & BTES Project presentations 

- Theo Venema (WarmteStad, NL) ATES Groningen PDF presentation
- Stefanie Dedeyne (BTB, DE) HT ATES Geospeicher Berlin PDF presentation
- Ingo Sass (TU Darmstadt, DE) Seasonal Crystalline BTES Darmstadt PDF presentation
- Martin Jutzeler (Energie Wasser Bern, CH) Large scale BTES Bern PDF presentation

Panel on ATES & BTES

- Speakers: Theo Venema, Stefanie Dedeyne, Ingo Sass & Martin Jutzeler.
- Moderators: Sebastian Bauer
(Uni Kiel, DE) & Bas Godschalk (IF Technology, NL)

Thermal, chemical & microbial impacts on groundwater by UTES

- Niels Hartog Causes and Considerations, (NL, KWR)  PDF presentation

PTES overview presentation

- Geoffroy Gauthier (PlanEnergi, DK) PDF presentation

Project Presentations

- Wim van Helden (AEE INTEC, AT) PTES TREASURE: Demonstrating 7 Pit Thermal Energy Storages in Europe PDF presentation

- Florian Hahn (Fraunhofer IEG, DE) MTES Bochum  PDF presentation
- Ria Doedel (Mijnwater, NL) MTES Heerlen  PDF presentation
- Jessica Dassow (Uni Edinburgh, UK) MTES UK overview & STEAM project PDF presentation

Panel on MTES & PTES

- Speakers: Wim van Helden, Florian Hahn, Ria Doedel & Jessica Dassow.
- Moderation: Geoffrey Gauthier
(PlanEnergi, DK) & Paul Ramsak (GI, NL)

Panel on UTES Strategy

- Speakers: Christian Minnig, Paul Ramsak & Stan van den Broek.
- Moderation: Hjalti Páll Ingólfsson
(GEOTHERMICA Initiative, IS)


- Christian Minnig (IEA Geothermal TCP) & Paul Ramsak (GI, NL)

The agenda is available here 












For more information, please get in touch with the GEOTHERMICA Initiative Office info@geothermica.eu or IEA Geothermal Secretariat iea-giasec@gns.cri.nz.