Présentations Colloques

Oral Presentation
Session 7.02: Urban Hydrogeology
Gaultier Gaëlle
Development of urban shallow groundwater geothermal systems : How to promote a sustainable approach while preventing potential conflicts over underground and groundwater use ? The case of Grenoble
Labelled Ecocity, Grenoble Presqu’île is a large urban development project (250 hectares) located at the confluence of the Drac and Isère rivers.**The semi-public Innovia Company, developer of this site, promotes the use of renewable energy sources and more particularly the use of shallow groundwater geothermal energy to cool the future buildings.**However the implementation of geothermal doublets, made of pumping wells (abstracting groundwater) and reinjection wells (reinjecting hot water in the aquifer) could lead to detrimental impacts to underground and groundwater uses.**Potential negative impacts includes notably the flooding of under-ground structures (car parks,…), extra parasite water inflow to leaky sewer pipes, lower efficiency of surrounding doublets due to recirculating waters, and at district or city level, regular groundwater temperature increase which could lead to water quality issues and limitations of geothermal use of aquifers. **In order to promote a sustainable development of geothermal energy within a complex urban context while mastering potential detrimental impacts, an innovative approach has been implemented by Innovia.**Firstly, Innovia, in collaboration with Artelia, has built a 3D groundwater and thermal model to assess the impacts of existing and future geothermal system schemes. Moreover the continuous survey of the aquifer (levels, temperature profiles) allows the monitoring of present impacts and the regular calibration of the model.**Secondly, in a context where a comprehensive regulation framework related to the use of groundwater as an energy source is yet to come, working procedures have been set. Any building permit, involving shallow-groundwater geothermal use, would be submitted to Innovia for an advisory opinion regarding the consistency of the envisaged scheme with respect to existing and future use of groundwater and underground. This twofold approach allows a mastered and sustainable development of shallow groundwater geothermal energy at a district level.