International Innovation Network for the Development of Cost- and Environmentally Efficient Seasonal Thermal Energy Storages

INTERSORES aims to provide the international market potential of sTES with high techno-economic and environmental performance.

The EU aims to quickly decarbonize the energy sector through the Fit for 55 package, RePowerEU plan and Green Deal. Large-scale seasonal thermal energy storage (sTES) technologies (Reno-sTes and Giga-CTES) can assist the effort by enhancing the use of fluctuating heat sources. The INTERSTORES will tackle these challenges and accelerate decarbonization through the application of advanced sTES technologies.

Project Outcomes:

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INTERSTORES - Innovative energy storage for the future

Demonstration and implementation of two innovative sTES solutions, validating the use through the demo sites as multi-purpose sTES. INTERSTORES aims to improve sustainability by using cost-effective, recycled insulation materials, increasing the use of renewable energy, and replacing standard shotcrete. Its core impact will be seen in the reduction of investment costs, energy requirements, reduction of CO2 emissions, and environmental and land footprint.

INTERSTORES Project Objectives

During the planned 48 months of the Project, we will advance Reno-sTES and Giga-CTES at two prominent demo sites in Finland and Germany with full-scale realisation and energy system integration. This will be feasible, as our industrial partners decided to cover most of the investment costs for implementing the sTES during the proposed project.


Reno-sTES & Giga-CTES

Develop a procedure for transforming infrastructure into seasonal thermal energy storage (Reno-sTES), and facilitate the safe realisation and integration of large-scale cavern thermal energy storage (Giga-CTES).



Understand and optimise environmental benefits from reused infrastructure (Reno-sTES) and large-scale cavern thermal energy storage (Giga-CTES).



Improve performance by the combination of multiple storage units and by integration of diverse sources and sinks.



Demonstrate two market-competitive, replicable seasonal thermal energy storage solutions.

INTERSTORES Project Innovation

We seek to conquer high capital costs by re-use of infrastructure that has previously served other purposes and now can be transformed in a renovated, low-cost, ground-based sTES facility (Reno-sTES) through busting the efficiency and the promotion of circular economy principles, reduction of environmental impacts, and land use.

The other direction we envisage is saving capital costs for building new sTES by utilizing natural environments as storage caverns viable in dense rock formations. INTERSTORES will integrate the worldwide largest rock cavern thermal energy storage (Giga-CTES).


Security of supply issues affect everyone and are a significant driver of solutions to climate change. INTERSTORES offers its high innovation potential to achieve: