Geothermal energy: a clean energy with great potential for heating homes and neighbourhoods in Luxembourg

Geothermal energy: National context and challenges

The NECP (National Integrated Energy and Climate Plan) recognises geothermal energy as one of the fundamental pillars for achieving renewable energy targets. In fact, geothermal energy is a promising source of renewable heat and can be used to decarbonise the heating sector. Near-surface geothermal energy is mainly used to supply heat to single-family homes and residences, while medium-depth geothermal energy can be used to supply heat to buildings or neighbourhoods with elevated heating requirements. En effet, la géothermie est une source d’énergie prometteuse pour fournir de la chaleur renouvelable et peut servir ainsi à décarboner le secteur du chauffage. La géothermie peu profonde sert principalement à fournir de la chaleur aux maisons unifamiliales et résidences tandis que la géothermie moyennement profonde pourra contribuer à la fourniture de chaleur aux bâtiments ou quartiers à besoin en chaleur élevé.

In order to explore the potential of medium-deep geothermal energy in Luxembourg, several studies have been launched, revealing a high potential in the south of the country, particularly in regions with a high density of energy needs. Exploiting medium-depth geothermal energy therefore appears to be the optimal solution. A number of pilot projects have been launched to gain initial experience of exploiting this potential, while at the same time identifying the main difficulties in Luxembourg.

What is geothermal energy?

Geothermal energy is thermal energy stored in the earth’s crust that can be extracted. In principle, it can be used for heating and cooling, for electricity generation or for the production of heat and electricity. It can also be used for combined heat and power. As a primary renewable energy source, geothermal heat is an alternative to fossil fuels and is becoming increasingly important in Luxembourg.

Heat is constantly radiating from the Earth’s core, and this, combined with solar energy, is what sustains life on the Earth’s surface. As a result, the temperature of the geological layers increases with depth. This geothermal gradient averages 30°C per kilometre, but it can also be higher or lower depending on the geological situation of the region. To harness this energy generally means drilling boreholes to extract the heat to the surface. Depending on the depth of the borehole, this is referred to as near-surface geothermal energy (up to 400 m) or middle deep geothermal energy (from 400 to 2500 m).

The use of deep geothermal energy requires certain basic geological conditions, such as hydrothermal deposits or hot rock formations close to the surface, which are not available in Luxembourg.