In France, the geothermal solution is widely promoted, explored and increasingly implemented, combined with other renewable energy sources, because it offers an exceptional carbon footprint and a relatively rapid return on investment. In several French cities, including Grenoble, geothermal schemes are being used to heat and cool buildings. However, this enthusiasm, particularly for groundwater projects, can lead to temperature changes in the aquifers that are damaging to the optimal running of all the facilities (too much hot water discharged into the aquifer in summer, and too much cold water discharged in winter).

In charge of the Peninsula urban redevelopment project in the city of Grenoble, SEM Innovia wanted to promote geothermal energy, while avoiding these problems. It therefore asked Artelia to create a hydrogeological decision-aid model to provide rational data and relevant advice on all development projects likely to have an impact on groundwater.

Our teams have summarised existing data, carried out additional investigations and created a 3D hydrogeological model of the groundwater at the confluence of the Drac and Isère rivers (approximately 5 km²). They also installed a monitoring network of 23 piezometers to calibrate the model both thermally and hydrodynamically. Recently updated, the model has been used to simulate more than a dozen geothermal projects and assess their impact on the Grenoble aquifer.