Geo4P - Geothermal Pilot Project Pisan Plain: quantitative assessment of very low, low and medium temperature shallow geothermal resources

Geo4P (Geothermal – Pilot Project Pisan Plain) is a Project started in July 2014 for the development of an innovative multidisciplinary methodology, aimed at carrying out a quantitative assessment of very low, low and medium temperature shallow geothermal resources in Pisa floodplain, and at identifying most suitable exploiting technologies, in different parts of the study area. The implementation of this methodology, and of resulting geology and energy related analysis methods, will indeed allow to test and develop procedures and tools, not yet used in a systematic and multi-sectoral way. Studies for the evaluation of the geothermal and energy potential of aquifers in the subsurface of the Pisan Plain, even to the lowest depths, have been carried out through investigations on existing scientific literature and on-field campaigns, to collect hydrogeochemical and hydrogeological data, as well as geothermal parameters (e.g. temperature) of waters sampled from springs and artesian wells in the study area. With these aims, stable isotopes of water oxygen and hydrogen analysis and other geochemical analysis have been carried out. The results, along with details of subsurface geology, will allow developing a reference conceptual model for underground flows of fluids in the multilayer system of the alluvial plain. About geothermal parameters, the investigation campaign allowed the collection of 200 temperature data, of which 30% in wells having filters positioned at defined depth, enabling the delineation of a good knowledge framework, under the underground thermal profile. Gravimetric surveys were then carried on a total of 974 stations, whose data are under interpretation. A 3D hydrogeological and thermos fluid-dynamics modelling of the aquifer system (thermal and not) in the study area will be then developed from obtained data and a map matching heat demand and shallow geothermal potential will be drafted. In terms of plant engineering, plant solutions will be identified in different parts of the study area, taking into account the sustainable use of geothermal resources, both under the economy related and environmental point of view, avoiding impacts in shallow aquifers. Once it will be validated, this methodology can be exported in similar contexts, in Italy and in Europe. Given that the Pisan Plain, constituting the end part of the Arno valley, despite its peculiarities, is a typical example of alluvial plain as many others throughout Europe, after being tested, this practice will be made available to local administrators, to start integrating hydrogeological and energy related data into territorial planning tools.