FLEXSTEAM – Development of heat storage for industrial steam

  • Status
  • Start date
    January 1, 2019
  • Runtime
    36 months
  • Contact
    Agata van Oosten
  • Project leader
  • Robert de Boer
  • ECN part of TNO

The FLEXSTEAM project aims to improve the way we can store and re-use  thermal energy by using so called ‘Phase Changing Materials’ (PCMs).

To achieve a fully circular economy we will have to be able to close our material but also our energy loops. Re-using, storing and upgrading energy is an essential part of creating a sustainable system. In the industry a large part of the energy usage comes in the form of heat.

Heat buffering is very important for the integration of heat pumps in existing industrial processes. By focusing on the efficiency of processes as well as replacing fossil resources with renewable ones we will be able to greatly reduce the industrial sectors’ dependence on fossil energy.

About the FLEXSTEAM project

A challenge lies in the storage of energy when the availability of sustainable resources to run for example the heat-pumps varies. Storing energy is in fact one of the biggest challenges we face in the energy transition because of the varying availability of renewable resources. Electrical storage is very expensive whereas thermal storage can be achieved relatively cheap by using so called ‘Phase Changing Materials’ or PCM’s. Often a composition of salts or organic materials, PCM’s change from solid to liquid and in the process store latent heat. This way they can store a lot of heat in a small amount of volume.

The technology developed will be used for the recovery and re-use of industrial leftover (waste) heat, directly as well as indirectly through the use of heat pumps. Apart from that it will also be able to increase the implementation rates of sustainable heat sources like geothermal and solar energy to generate process heat. Both can be used more effectively and efficiently if a thermal energy storage solution is present.

The FLEXSTEAM project is a joint exercise by TNO (project coordinator), ISPT, Royal Cosun, DOW, TataSteel B.V, Blue Terra and Bronswerk.


In the project three end-users work together to develop a prototype where the heat-storage is based on PCM technology that is impregnated with heat-conducting materials in order to yield the necessary thermal output. The selected combination of PCM carrier material will be tested on a lab scale and a method will be developed for impregnation and production on an industrial scale. This will result in a PCM heat-storage concept that has been tested dynamically and will be ready to scale up for industrial application. This will be the basis for further development of a pilot scale project.

Grant provider

This project is co-funded with subsidy from the Topsector Energy by the Ministry of Economic Affairs and Climate Policy.

Sustainable development goals

This project contributes to the UN Sustainable Development Goals.

Project partners

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