All about energy in Brussels. A Sibelga initiative
en menu
Logo energuide

What is geothermal energy?

Heat your house using heat from the ground? It's possible! Geothermal energy has been well known for a long time and is now back in fashion. It is also deployed in several parts of the world (Iceland, Germany, Denmark, France, Italy, Sweden, etc.). Non-polluting, renewable and free, this energy source is of interest in the fight against global warming.

The principle of geothermal energy

The temperature at the earth´s core is estimated to be between 2000°C and 12000°C, and the heat flows gradually up towards the earth’s surface. And that opens up interesting possibilities, because this natural heat can be transported.

For example, the earth´s heat can already be extracted from a depth of less than 5 m via a coolant that circulates in a buried pipe. Another option is to first convey water downwards and allow it to heat up before pumping it back up again.

In some places hot water is located at a great depth and only has to be brought up to the surface. At a temperature of 70°C or higher, the pumped-up water is already suitable for domestic heating, and when it is hotter than 100°C, it can be used to generate electricity.

Did you know that the deeper you drill, the hotter it becomes? In Belgium and the Netherlands, with each kilometre you descend the temperature rises by an average of 30°C, and boreholes around 2 km deep are necessary for district heating. In Iceland, by contrast, a borehole to this depth immediately delivers several tens of MW of electrical current.

Types of geothermal energy

Geothermal energy can be used in several different ways. Which method is ultimately chosen depends on the local situation and the required temperature.

Very shallow geothermal energy (<5m)

If you have a large area of land, consider installing a capture system. This consists of burying a pipe 5 metres below the ground surface. This relatively long pipe contains a liquid heat exchanger and is connected to a heat pump.

Shallow geothermal energy (50-300m)

This solution is ideal for large buildings in the city. It is more efficient and also more expensive and more complicated to implement technically. From a practical point of view vertical drilling takes place to a depth of 10 to 300 metres. The pipes are also connected to a heat pump, and can either contain a special liquid or underground hot water (if available).

Deep geothermal energy (>1000m)

This is the solution used by urban heating networks and electricity power plants. The ground is dug up top 1000 metres down and provides the superheated steam needed for these large installations.

Advantages of geothermal energy

The warmth of the soil will remain constant and available as long as our planet lasts. In addition, in summer and winter, the soil has a constant temperature of 12°C at a depth of 5 metres (in our latitudes). Your heating system will work even during the harshest winters!

The costs of installing a geothermal system are high but the systems can run for 50 years with very little maintenance. The profitability of the investment is guaranteed!

Is geothermal energy possible in Brussels?

The subsoil of Brussels is very suitable for shallow geothermal energy (up to 200 metres). Drilling is currently being carried out to map Brussels's geothermal potential.

If it is properly exploited, geothermal energy could contribute 10% of a city's heat requirements!

Find out more about geothermal energy in Brussels

Don't miss our new tips

Subscribe to our newsletter and stay informed about energyfacts.

We promise we will only use your data to send you our newsletter as stated in our privacy policy.

Did you find this article useful?
How could this article be improved?

We promise we will only use your data to send you our newsletter as stated in our privacy policy.

Tips on how to save energy!

We promise we will only use your data to send you our newsletter as stated in our privacy policy.