HOT|COOL NO. 1/2020 - "How to District Energize your City"

Aquathermal Aquathermal energy is a unique source of heat and cold. In the Netherlands it has a great potential to partly provide the heat demand of the built environment.

Earthquake victory for the environment The Netherlands has for a long time been able to sustain heat to houses and utility buildings with its own natural gas extracted in the province of Groningen, the northernmost part of the country. The comfortable and ‘unlimited’ supply of natural gas meant the insulation of houses was not first priority – until now. In recent years, due to the natural gas extraction, multiple earthquakes have occurred in the province. The earthquake issue in Groningen has a positive effect on the awareness of natural gas enhances climate change. This awareness plays an important role as the Netherlands is committed to the Paris Agreement. In regard to the alternatives for sustainable heat, the focus is on Denmark as one of the most energy efficient countries in the world because of a well-developed district heating (DH) infrastructure. By making rigorous choices decades ago, Denmark has a pole position in district heating >70˚C. The Dutch are inspired by this Danish District Heating Model, but the development of the DH is a challenge. Not only financial but also as forming new governance and ensuring enough sustainable heat to meet the demands. The Dutch Water Authorities are convinced that aquathermal energy, heat (and cold) from surface, waste and drinking water, is a new energy source that can provide sustainable warmth.

Foreign examples Ever since the Green Deal Aquathermie was signed, the participants have been working to make aquathermal energy an indispensable part in the energy transition. While working on raising awareness for aquathermal energy in The Netherlands, a search for aquathermal energy projects abroad started. Several TEA projects were found, for example in Turku, Finland, but TEO and TED projects are hardly developed. How does it work? Technically it is a simple concept to get the heat from the source to the building. The heat (or cold) is extracted from the surface, waste or drinking water using a heat exchanger. The technique uses low temperature heat (20-25˚ C) which is enhanced to the desired temperature (40-70˚C) with the aid of (collective) heat pumps and distributed to houses and utility buildings with a DH grid. The most energy efficient method for TEO and TED systems is to store the heat in the summer for use in the colder winter months. Dutch examples of a TEO-projects are Blaricum, Heeg and Amsterdam. In Blaricum over 700 newly built houses are connected to a DH grid using aquathermal energy. The grid will be extended to other houses. The latter two TEO projects are in advanced stages of preparation. The TEO project in Heeg is an initiative by the local people who want to make the heating of their houses sustainable by using the lake water nearby; in Amsterdam the municipality is constructing a new residential area Strandeiland, with a DH grid using aquathermal energy from the lake IJ.

Aquathermal energy as an alternative heat (and cold) source

The Netherlands is a country rich in water and no matter where you are, water is almost always near. The high density of waterways’ result in the fact that supply and demand of heat and cold from water can be achieved in nearby. Research from 2018 shows that aquathermal energy (in Dutch: TEO, TEA and TED )* can provide in a significant part (<50%) of the heat demand of Dutch households, utility buildings and greenhouses. TEO has by far the greatest potential due to the large availability of surface water. TED has the least potential, because the source is only available in small quantities and in specific locations. The Netherlands is continuously researching the possibility of using aquathermal energy as an alternative heat source for natural gas-free districts. In May 2019, a large number of parties signed the so calledGreenDeal Aquathermie with the Dutch Water Authorities, Rijkswaterstaat (the agency of the Ministry of Infrastructure and Water Management) and the Ministry of Economic Affairs and Climate. The Green Deal is used to bring aquathermal energy to the attention of stakeholders and to develop and share knowledge about aquathermal energy to further develop this technique.

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Heat demand built enviroment 2050

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* TEO, TEA and TED = Thermal Energy from surface (Dutch: Oppervlakte), waste (Dutch: Afval) and drinking (Dutch: Drink) water.

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