Test Facility for Thermal Energy Storage in Molten Salt (TESIS:store)

The Test Facility for Thermal Energy Storage in Molten Salt (TESIS) at the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) DLR Institute of Engineering Thermodynamics in Cologne is the first research facility for molten salt storage and technology at a significant scale in Germany. This large-scale research facility is used to develop and improve thermal storage capabilities and the molten salt technology that is used to store energy produced from renewable sources.

The test facility trials technology on the scale of one megawatt hour – far beyond the energy levels reachable in a laboratory. As such, research here takes place under conditions representative of those in real-world industrial applications. These applications include energy-intensive industrial processes such as the production of steel, iron, non-ferrous metals, glass, cement and chemical products.

Molten salt storage can increase the energy efficiency of these processes. It can also be incorporated into power plant technology to stabilise fluctuating and volatile power generation from renewable energy sources. Molten salt storage systems are already being used commercially for demand-driven power generation in solar thermal power plants. These thermal storage systems can also be integrated into conventional fossil fuel power plants to improve their flexibility or to convert them into heat storage power plants.

TESIS:store – the largest facility for the development of new single-tank storage concepts

TESIS is a twin programme consisting of two subsystems – TESIS:com and TESIS:store. TESIS:store is the world’s largest research facility dedicated to the development new single-tank storage concepts for high-temperature heat storage. Storing excess heat in just one tank, instead of the usual two, can reduce capital costs by up to 40 percent while halving heat losses. Research is directed at issues such as material compatibility, heat and mass transfer, thermal mechanics and the integration of storage systems.


Volker Speelmann

Head of Research Infrastructures
German Aerospace Center (DLR)
Executive Board department for Innovation, Transfer and Research Infrastructure
Linder Höhe, 51147 Cologne

Thomas Bauer

German Aerospace Center (DLR)
Institute of Engineering Thermodynamics
Linder Höhe, 51147 Cologne