WINDOW: More sustainable heating in the Netherlands through subsurface heat storage

Marette Zwamborn, Niels Hartog PhD, Martin Bloemendal MSc PhD, Stijn Beernink MSc

  • Start date
    01 May 2019
  • End date
    30 Sep 2020
  • Principal
    TKI Watertechnologie
  • collaborating partners
    KWR, TNO, Deltares, IF Technology, Eneco, Vattenfall, HVC, Ennatuurlijk, SVP, Provincie Zuid-Holland, Provincie Limburg, Gemeente Den Haag, Rijkswaterstaat, Shell, EBN, Engie, Hydreco Geomec

The WINDOW project focuses on the subsurface storage of heat. The implementation of subsurface heat storage at temperatures above 40°C is still very limited in the Netherlands. In the WINDOW programme we aim to remove technical, legal and commercial obstacles, so that subsurface heat storage can be implemented as a proven technology in 2025. Heat storage contributes to reducing costs in the heat transition and ensures an optimal exploitation of sustainable heat sources.

Subsurface heat storage.

In WINDOW phase 1 (2019/2020), explorative studies will be done on five promising sites in collaboration with all the participating stakeholders (‘learning by doing’).

Subsurface heat storage: opportunity and challenge in the heat transition

The storage of heat in the subsurface is an important component of the heat transition and constitutes one of the cheapest forms of energy storage. It is important that the summer heat surpluses (from geothermal energy, industrial residual heat, solar or wind energy) be stored for later use in the winter.

Subsurface heat storage at temperatures above 40°C is however still only implemented to a very limited degree in the Netherlands. There remain important challenges, with regard to the technology, the effects, the robustness of the business case, and the relevant legal framework. Knowledge development, knowledge sharing and experience are required for a faster and responsible implementation of subsurface heat storage in the Netherlands.

Subsurface heat storage permits the optimal exploitation of renewable heat sources like geothermal energy and residual heat.

Further developing subsurface heat storage into a proven technology

The objective of the WINDOW programme is to remove technical, legal and commercial obstacles to subsurface heat storage, and to gain a better understanding of its effects, with a view to the responsible implementation of the technology to promote the sustainability of the heat provision in the Netherlands. We are doing this by exploring and supporting (the preparation of) demonstration projects in the country, and sharing and applying the resulting knowledge and experience in the joint development of generic tools, in close collaboration with stakeholders and policy-makers. The ultimate objective is to have subsurface heat storage implemented as a proven technology in 2025. The results will contribute to reducing the costs of collective systems at the system level, and to an optimal exploitation of the renewable heat sources.

Phase approach, ‘learning by doing’ with supporting research

The project consists of four work packages:

A. ‘Learning by doing’ from exploration to demonstration project
B. Generic research: Potential & Integration
C. Generic research: Technology & Effects
D. Authorisations/legal assessment framework

The WINDOW project is divided into two phases; all of the work packages continue through the two phases.

WINDOW phase 1 (2019/2020) is a TKI project (TKI Urban Energy, TKI New Gas and TKI Water Technology). In phase 1, five to six promising sites have been selected on the basis of 21 quick scans. These promising sites will now be explored in collaboration with all the participating stakeholders (work package A: ‘learning by doing’). The exploration sites are spread throughout the Netherlands, and vary in project size, temperature level and geohydrological situation.

Work packages B, C and D contribute to the explorations in work package A, while also developing generic insights. This generic research includes:

  • Sketch of the main outlines of the financial frameworks and system perspective at a national scale.
  • First version of ThermoGIS-HTO and high temperature storage (HTO) potential maps in the Netherlands.
  • Identification and prioritisation of the key knowledge and/or technical gaps regarding source technique and water treatment.
  • Insight into the relations between site-specific factors and recovery performance.
  • Literature study and identification of the key knowledge and/or technical gaps regarding microbial and chemical effects.

WINDOW logo.

WINDOW phase 2 (2020/2023) will be carried out within the innovative sustainable heating collective, WarmingUP. In phase 2, two state-of-the-art designs for demonstration projects will be elaborated in work package A (‘learning by doing’), including a finalised decision-preparation for investors and the competent authority. The generic research of work packages B, C and D continues in phase 2.

The WINDOW programme builds on the results of recent studies in the field of subsurface heat storage, including for instance the development of an HTO system at Koppert Cress, the European HEATSTORE project and the Power-to-X (SPX) project. The WINDOW research will make optimal use of knowledge and experience from existing heat storage systems and of ongoing research, and no subjects will be doubly researched.