Energy tunnels as an opportunity for sustainable development of urban areas

The use of renewable energies will be increasingly necessary to reduce carbon dioxide emissions. An important contribution can be provided by energy tunnels, which make it possible to draw on a form of clean, renewable and locally accessible thermal energy for heating and air conditioning of buildings. The paper describes the characteristics of an energy tunnel and the design aspects necessary for its conception. Explicit reference will be made to the studies conducted at the Politecnico di Torino which led to the development of an innovative energy segment then used to create an experimental prototype in the true size of an energy tunnel. The data collected allowed to evaluate the performance of the system and to study the possibility of thermally activating the tunnels of the future Line 2 of the Turin Metro, allocating the heat partly to the air conditioning of the stations and partly to external users. With a view to sustainable urban development, the possibility of integration with district heating systems and the possible creation of local heat distribution networks at different temperatures, directly connected to the underground infrastructure, is particularly attractive and promising.