Evaluating the technical and economic feasibility of energy tunnels

While the opportunity to equip tunnels as energy geostructures for the recovery of heating and cooling energy is being widely considered for new infrastructures, the evaluation of the technical and economic feasibility of such innovative installations has yet to benefit from a systematic approach.

In collaboration with CSD Engineers and the specialized firm GEOEG, researchers from the Laboratory of Soil Mechanics at EPFL propose a newly developed methodology to that end, in a recent paper entitled "Energy performance and economic feasibility of energy segmental linings for subway tunnels" published in Tunnelling and Underground Space Technology. This publication presents, among other findings, the application of this methodology to a case study from the TBM excavated tunnels of the future Grand Paris Express, based on the actual characteristics of the infrastructure and the local geological conditions of the Parisian basin in the surroundings of the Chelles station.

For a representative segment of this infrastructure, the article discusses numerous design solutions typically considered for those systems as well as their influence on the energy performance of the installation and, more generally, on the future profitability of the energy supply based on this renewable resource. The employed methodology allows one to understand and take into account the necessary trade-offs for the optimal design of those installations.