From heating and cooling to generating electricity and even extracting lithium, we have summarised the various uses of geothermal energy for you.
Below is an infographic from Géosciences journal No. 27 published in September 2023, which provides the latest information on this topic.
3 October 2023

Geothermal energy is the technology used to harness the energy available beneath the earth's surface.

The subsurface temperature increases with depth. This is known as the geothermal gradient. On average in mainland France, the subsurface temperature rises by 3.3°C per 100 metres in depth.

Deep geothermal energy is a sustainable way of producing heat that can be used directly to supply heating networks and industrial or agricultural processes. Very roughly speaking, at a depth of 2000 metres in the Paris Basin, for example, heat can be captured at a temperature of around 80°C. In some geological contexts (collapse trenches and volcanic areas), it can also be used to generate electricity.

At depths down to 200 m, the inertia of the subsurface temperatures is used for heating and cooling. This energy is then recovered using a heat pump. This is known as near-surface geothermal energy. It can be used on a scale ranging from single-family houses to eco-districts for heating and cooling, as well as for agricultural and industrial purposes.

"Which geothermal energy for which uses" infographic taken from the 27th edition of Géosciences published in September 2023.

Infographie "Quelle géothermie pour quels usages ?", issue de la revue Géosciences n°27, parue en septembre 2023.

© BRGM

  • Chaleur / eau chaude en réseau : le niveau élevé de la température de l’eau permet son utilisation directe pour alimenter les réseaux de chaleur (géothermie basse énergie).
  • Chaud / froid à usages agricoles et industriels : l'eau géothermale peut être utilisée, avec ou sans pompe à chaleur, pour le chauffage et la climatisation de serres agricoles, pisciculture, usages industriels (géothermie basse et très basse énergie).
  • Chaud / froid / eau chaude sanitaire à usages domestiques et tertiaires : les pompes à chaleur géothermiques sur aquifères superficiels ou sur sondes permettent le chauffage, le refroidissement, la production d’eau chaude pour des immeubles, des bâtiments tertiaires et des maisons (géothermie très basse énergie).
  • Électricité / chaleur / lithium : la température des milieux fissurés à grande profondeur permet de produire de la chaleur et/ou de l’électricité. Dans certains territoires, du lithium peut être extrait des saumures géothermales (géothermie moyenne et haute énergie).
  • Électricité : l'eau est captée à haute température, souvent sous forme de vapeur, pour la production d’électricité (géothermie haute énergie).
Cover and extract of Issue 27 of the Géosciences journal.

Cover and extract of Issue 27 of the Géosciences journal.

© BRGM

Geosciences No. 27: Subsurface solutions for the Energy Transition

Geothermal energy, CO2 or heat storage, access to mineral resources and more. This issue of Géosciences looks at the potential of the subsurface for the energy transition.

Associating the subsurface with the energy transition may appear incongruous. Wind turbines, photovoltaic panels, or possibly hydroelectric dams and nuclear power stations come more readily to mind. And yet, the energy and ecological transition that will gradually lead us to develop low-carbon energy will require us to make increasing use of the resources and potential of the subsurface.

Issue 27 of BRGM's Géosciences magazine investigates subsurface solutions: geothermal energy, CO2 storage, heat storage and hybridisation of these different solutions with other sources of renewable energy. It also looks at access to mineral resources, which are vital to the success of the energy transition.