Geothermal energy is that found underground. Despite fluctuations in temperature during the various seasons, a few feet below the surface of earth's crust remains at a stable temperature. Geothermal heat pumps use this heat in order to increase the efficiency of heating systems.

They do so through pumping cool air in the winter down into pipes below the crust. The air becomes warm under ground and is then pumped back into the house, where the energy can be distributed. In the summer time, hot air can be pumped underground to cool it down, resulting in a stable year round temperature inside the living space.

The key technology is a Ground heat exchanger (below)

While this example is at the household level, Engie supplies networks of buildings with heat.

Engie aims to decarbonise energy sources to reduce associated emissions. Their technology supplies a district of buildings with heat from geothermal sources through a distribution network, providing them with local and flexible renewable decarbonisation of heating.

While the technology of Geothermal pumps is not new, Engie’s innovation lies in altering and adding to the conventional technology.

They have also explored the use of underground reservoirs containing naturally heated water for the heating of buildings. Their multidrain solution doubles the productivity of a conventional pump.

The US Environmental protection agency recognises Geothermal systems as the most environmentally clean and energy efficient solution to conditioning spaces.

Sources:

ENGIE. “Geothermal Energy.” Engie.com, 2022, https://www.engie.com/en/activities/renewable-energies/geothermal-energy.