Application of energy tunnels to an urban environment

tDeep and shallow foundations, diaphragm walls, tunnel linings and anchors are being increasinglyemployed as energy geostructures in Europe and all around the world. Besides being constructed fortheir primary structural role, they are equipped to be able to exchange heat with the ground and supplythermal energy for heating and cooling of buildings and de-icing of infrastructures. This technology canplay a fundamental role in the current challenge of addressing the increasing need for clean and renew-able sources of energy. This paper investigates the possibility of thermal activation of a new section underconstruction of the Metro Torino line 1 (Italy) to heat and cool adjacent buildings. The design and opti-mization of the geothermal plant, the quantification of the exploitable heat and the assessment of theeventual consequences on the surrounding ground are here discussed. For this purpose, thermo-hydrofinite element analyses, able to capture the key aspects of the problem, were conducted. A 3D model isdevoted to study the efficiency of the system, reproducing one ring of the instrumented tunnel segmentallining, while a 2D large scale model of the Torino aquifer is conceived to investigate the sustainability ofthe technology in terms of effects on the surrounding environment. Based on the results of the compu-tations, it can be anticipated that, thanks to the favorable underground water flow conditions in Torino,the system would allow 53 and 74 W per square meter of tunnel lining to be exchanged during winterand summer respectively.