Geothermal energy: harnessing the Earth's heat

Geothermal energy is a renewable energy that covers all the technologies used to exploit the Earth's internal heat. It can be used to produce heat, cold and electricity. 
18 December 2019

How is geothermal heat harnessed?

Geothermal water taken from an aquifer can be used to power a district heating network, a system that is widely used in the Ile-de-France region.

© CFG Services

How do you produce electricity using geothermal energy?

Geothermal energy is a renewable energy drawn from the Earth's internal heat. It can be used to produce electricity, in particular. How a geothermal power plant works, explained in pictures.

© CFG Services

BRGM's experimental geothermal platform

The experimental platform for geothermal heat pumps is designed to study underground heat exchangers. Situated on BRGM's site in Orléans, the platform was co-financed by the Centre region (Orléans, France, 2010).


BRGM's geothermal platform in Orleans compares the efficiency of various techniques to exchange heat, in summer and winter, between buildings and the subsoil. The goal of the platform is to describe the mechanism of conditions, such as wind, rain, sun, and the Earth's heat. Understanding the resource will help us to manage and use it better. The first systems installed and studied were horizontal collectors. This simple and economical technique is not the most efficient, but it gives us keys to understand other collectors. We can also choose to stabilise the thermal resource by using vertical geothermal probes. The same is done with aquifer solutions. Today, we are also finding intermediate solutions, such as the systems known as compact exchangers. Their efficiency has not yet been fully studied, but their simple installation with a digger makes this system the ideal companion for future green houses and buildings. By circulating water in the exchangers at a fixed temperature and outflow, we can simulate energy needs in terms of heat and cold for any building. We can reproduce the behaviour of homes, of all existing heat pumps, and those which are still concepts. This installation shows nearly 10,000 temperature measurements every 2 minutes with optical fibre technology. Two engineers, 2 PhD students and one control systems technician were hired to run the platform.