About GTD

What is geothermal energy? 

Geothermal energy is heat from deep soil layers. Deep in the subsoil, in porous sand- and stonelayers, in various places in The Netherlands, hot (salt) water is stored. The deeper into the earth, the warmer the water gets. 

With every kilometre of depth, the temperature rises by about 31˚C. This heat can be used, among other things, to heat buildings. The hot water, of about 75 degrees Celsius, is pumped upwards via a 2,2 kilometre deep well located in Delft. 

The heat from the ground water is transferred via heat exchangers to a closed pipe-system (heat network) containing fresh water. This is used to heat the buildings. The groundwater cools down to about 50˚C and is returned to the layer via a second well. This well is at a distance of one and a half kilometres from the first well. 

See further information: www.allesoveraardwarmte.nl 


Why geothermal energy?

By 2030, the Netherlands wants to halve its CO2 emissions compared to 1990. This means that by 2030 a total of 1.5 million existing homes must be heated through the use of sustainable energy. To realise a sustainable energy supply, it is necessary that residents and companies use less energy and furthermore utilise more sustainable sources for energy, heating and cooling. 

Geothermal energy offers sustainable, renewable heat. Geothermal energy is a heat source that releases hardly any CO2, which is why this source of energy contributes to making the Dutch energy system more sustainable. It is a sustainable and reliable alternative to natural gas. This geothermal project contributes to achieving our climate objectives. 

Advantages and disadvantages of geothermal energy

Geothermal energy has several strengths compared to other energy or heat sources, but there are also some points of interest. Municipalities and regions have to make a good decision before opting for geothermal energy. This overview lists the advantages and disadvantages of geothermal energy.

The benefits of geothermal heat

  • Local: the heat comes from a local source and is therefore obtained close to the users.
  • Renewable: the water is automatically brought up to temperature underground again.
  • Reliable: the extraction of geothermal heat is always possible and does not depend on weather influences, as is the case with the generation of wind or solar energy.
  • Stable costs: the costs of geothermal energy are stable and predictable for a longer period of time.
  • Sustainable: geothermal energy fits within a sustainable energy mix because hardly any CO2 or particulate matter is released during extraction, transport and use.
  • Circular: with geothermal energy extraction, water is pumped up and returned: no volume is extracted from the earth, which can lead to a change in the 'earth balance' - as with gas extraction.
  • Hardly any impact on the environment: the extraction of geothermal energy does not cause any odour, dust, visual or noise pollution. During the construction, there will be construction noise and some light nuisance (due to working at night).
  • Large scale: an installation can provide for a considerable heat demand (each geothermal installation can supply up to 30,000 homes with heat.
  • Independent of weather influences: the extraction of geothermal energy is always possible and does not depend on wind or sunlight, as is the case with the generation of wind or solar energy.
  • Limited nuisance: the extraction does not cause any odor, dust or noise pollution, with the exception of nuisance during construction.
  • Requires little space: a geothermal installation takes up limited space above ground, so that there is a minimal spatial impact on the environment.
  • No effect on humans, animals and plants: as far as is known there are no effects on humans, animals and plants or the subsoil.
  • Short energy payback period: geothermal energy installations have an 'energy payback period' of a few months: in that period the CO2 emissions, caused by the required steel production, drilling, etc., are earned back by saving on fossil energy (natural gas).
    In many places, the Dutch soil is suitable for geothermal heat extraction, because there is a lot of water in the subsurface.

The disadvantages of geothermal heat

It is of great importance that geothermal heat extraction has no negative consequences for people and the environment. The exploration and production of geothermal energy is subject to strict laws and rules. State Supervision of Mines supervises the enforcement of this.

Partly due to the earthquakes caused by gas extraction in the Northern Netherlands, there are social concerns about comparable consequences for geothermal heat extraction. Read more about the risks or read more about geothermal heat nearby. From concept to implementation takes a closer look at the process and the phases that are passed through in the development.

  • Not applicable everywhere: sufficient heat must be available for extraction in the subsoil.
  • Some locations are excluded: protected nature areas and drinking water extraction areas are excluded for geothermal heat extraction. In earthquake-prone areas, geothermal energy is not allowed or additional safety measures are required. Read more about risk mitigation and safety here.
  • Heat comes from deep underground: in the Netherlands we have to go deeper into the ground than in some other places on earth to reach the right layer of the earth.
  • Expensive investment: geothermal energy is an expensive investment, relatively 'young' technology.
  • Not suitable for individual heat demand: geothermal heat is a collective heat supply. An individual heat user cannot opt ​​for geothermal energy
  • Collaboration necessary: ​​to extract geothermal energy cost-effectively, thousands of homes (and/or several companies) must be connected in the vicinity of the extraction location. Collaboration between various parties is necessary and requires time and attention.
  • Nuisance during construction: the construction of a geothermal energy installation can cause nuisance for local residents
  • Heat infrastructure necessary: ​​for the use of geothermal heat, there must be a heat network nearby.
  • Low risk of vibrations: there is a very small risk of earth vibrations in the area during the exploration and drilling of the wells.
    Limited experience: no geothermal installation has yet reached the estimated lifespan of 30 years. There is as yet no experience with the entire life cycle of a geothermal energy installation.


The partners in the project: TU Delft, Hydreco Geomec BV, Energie Beheer Nederland BV and Shell are developing and realizing a high-quality geothermal installation on the TU Delft campus. The management, exploitation and acquisition of sustainable energy go hand in hand with the simultaneous implementation of a scientific program as an integral part of the project. 

Hydreco Geomec is a developer and producer of geothermal energy. We have been doing this for more than 10 years, with a lot of passion and a clear mission. We want to play a major role in the energy transition. Hydreco Geomec believes that the heat from our own earth will contribute significantly to the transition to sustainable energy. That is why we are fully committed to making the necessary improvement and acceleration of this technology. So that we leave a healthy earth for the next generations. Hydreco Geomec is a subsidiary of ENGIE. 

As a university, TU Delft is the driving force behind the scientific research program of Geothermie Delft. Moreover, TU Delft is the land owner and the first user of geothermal energy. By connecting scientific research and innovation to a working geothermal source, we get unique research opportunities. The proximity of this working resource offers enormous advantages for research and education. With the insights we gain, we can help other geothermal projects in the Netherlands and beyond. By using geothermal energy and sharing new insights, we make an important contribution to the climate objectives of TU Delft itself and those of Delft and the Netherlands. 

EBN is a company active in the energy sector, whose shares are 100% owned by the Dutch state. For 60 years, EBN has been using knowledge, expertise and strength to make an active and significant contribution to our future sustainable energy system. We are committed to the energy transition and turn social ambitions into reality. Energizing the transition. For more information about EBN, go to www.ebn.nl 

Shell wants to play a role in the energy transition. Shell sees good opportunities in the Netherlands for using geothermal energy to make the heat supply more sustainable. Shell has knowledge and expertise of the subsurface, the extraction of energy and the realization of large projects. With geothermal projects such as in Delft, Shell Geothermal wants to contribute to the Dutch heat transition. For more information, visit www.shell.nl  

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