Thermal energy from drinking water: TED

Under the Climate Agreement the Dutch government has made commitments to reduce CO2 emissions. The built environment is one of the sectors mentioned in the agreement. The biggest challenge in making homes more sustainable concerns their demand for heat: heating accounts for the largest part of the total energy demand of existing homes. Aquathermal energy (‘heat from water’) is one of the options for the sustainable heating of existing neighbourhoods. And one of the forms of aquathermal energy is TED: Thermal Energy from Drinking Water. Within the Aquathermal theme of the WarmingUP programme, KWR is studying the conditions under which TED can be safely implemented.

In carrying out this research, KWR is also fulfilling its pledged contribution to the Green Deal Aquathermal Energy. In doing so, KWR is working in close collaboration with the Network Aquathermal Energy, a network which connects all the signatories of the Green Deal Aquathermal Energy.

Principe van TED en koppeling met een WKO-installatie (in dit geval voor levering van koude uit een ruwwaterleiding). Bron: website Dunea

The TED concept and its connection with an ATES installation (in this case, for the supply of cold from a raw water pipeline). Source: Dunea website.

What is aquathermal energy?

Aquathermal energy is the collective name for the thermal energy that can be extracted or recovered from water sources in the vicinity, for the provision of heat and/or cold. A distinction is made between thermal energy from surface water (TEO in its Dutch acronym), from wastewater (TEA) and from drinking water (TED). Each category can be further subdivided into different types depending on the sources. For example, a distinction can be made within TED between raw water and purified water. In contrast with most other sustainable energy sources, aquathermal energy can actively reduce summer heat stress by extracting heat from water in the summer and, combined with seasonal subsurface storage (ATES), enable its use to replace fossil energy sources in the winter.

Aquathermal energy is a ‘low temperature (LT) heat source’. This means that it still requires a heat pump to bring the heat level to a temperature suitable for heating. The temperature required depends on the degree of insulation (energy label) of the object to be heated. All RESs (Regional Energy Strategies) consider aquathermal energy as a sustainable LT heat source. More than half of the RESs also refer specifically to Thermal Energy from Drinking Water (TED) as an option. The energy transition thus presents the drinking water sector with a question: To what extent can the current drinking water infrastructure be used to contribute to the heat transition?

Knowledge development needed for scaling up TED

Aquathermal energy and TED is not a new technology. TED has been implemented in the Netherlands for about 15 years now, including in collective heating applications – the Culemborg neighbourhood of EVA-Lanxmeer is an example. A key question concerns the extent to which TED can be scaled up, while preserving the primary mission of the drinking water utilities, namely: the provision of drinking water of impeccable quality.

An answer to this question requires more knowledge about the thermal potential of TED, and its application possibilities in relation to quality parameters. These are the types of questions that make up the research agenda of the Green Deal Aquathermal Energy and take concrete shape in the WarmingUP research programme.

Plaatsing warmtewisselaar voor TED-installatie Waternet/Sanquin. Bron: Website Waternet

Placement of the heat exchanger for the TED Waternet/Sanquin installation. Source: Waternet website.

What is KWR doing in theme 3 of WarmingUP?

Within theme 3 of ‘Aquathermal Energy’ in WarmingUP KWR is engaged in the following activities:

As part of project 3A:

Technical potential of TED available on the public aquathermal energy viewer.

  • Objective: make knowledge about the technical potential of TED available to a broad public. The viewer’s aim is to connect municipalities and project developers via the potential map to drinking water utilities as the source owners of thermal energy.
  • Result: The map with the technical potential of TED on district level is now available on
  • Contact: ir. A. (Andreas) Moerman

As part of project 3B:

Research microbiological effects of the use of different materials and water types in the temperature range of 15 – 30 °C. This research has two components:

  1. Lab study in which drinking water flows through a heated set-up, and to which different types of opportunistic pathogens are dosed.
  2. Repetition of the same study, but with surface water as the raw material for drinking water instead of groundwater (on-site).

In all of the experiments the behaviour of the dosed opportunistic pathogens will be studied in relation to the above-mentioned parameters.

  • Objective: develop knowledge about the possible microbiological effects of the warming of drinking water in the winter and its cooling in the summer.
  • Contact: dr. N. (Nikki) van Bel
Opstelling voor microbiologisch onderzoek binnen project 3B in de proefhal van KWR.

Set-up for microbiological research within project 3B in KWR’s test hall.

Validation of the KWR water temperature model, which allows a prediction of how much thermal energy (in series) can be extracted.

  • Objective: development of a water temperature model which, on a smaller scale (a few hundred meters of pipe), can perform reliable calculations of local temperature changes in the drinking water pipe network.
  • Contact: dr. ir. E.J.M. (Mirjam) Blokker

An exploration of the possible soil impact of large-scale implementation of seasonal heat storage (ATES).

  • Objective: provide a first indication of the possible impact of large-scale implementation of ATES on the distribution of soil pollutants, as input to follow-up projects for the optimal planning of the subsurface.
  • Contact: dr. ir. J.M. (Martin) Bloemendal

As part of project 3C:

TED Expert Document, consisting of an operational management best practice and a design guide.

As part of project 3M (pilot projects):

Study of performance of current TED systems, and research into possible correlations, for instance with weather parameters.

  • Objective: Develop knowledge about the actual performance of TED systems, as input for future business cases.
  • Contact: dr. ir. D.J. (Daniël) Bakker

Comparison of the design and management of drinking water networks and spring networks

  • Objective: to provide drinking water companies with insight into knowledge (gaps) within their own company relevant to the design and management of very low temperature (ZLT) heat networks (also called source networks).
  • Contact: ir. A. (Andreas) Moerman


Presentation at 2020 Water-Energy-Nexus conference, with explanation of TED and of results of KWR research over 20113-2019 (English).