The goal is the construction of a test plant to assess the feasibility of an advanced adiabatic compressed air energy storage (AA-CAES) system with thermal energy recuperation. For the test plant, a section of a dismissed tunnel excavated between Loderio and Pollegio (TI) for construction purposes of the Gotthard Basistunnel will be used and adapted correspondingly. The geological conditions of the selected tunnel section might be considered representative for the crystalline portion of the Swiss Alps. The aim of the pilot plant is to test and evaluate the design and operational conditions of the different plant components including the behaviour of the rock massif under cyclic charging/discharging operation. A future scale-up of the AA-CAES system could achieve efficiencies in the range of 75% and thus would be an attractive option to handle power fluctuations in the fast-growing electricity generation from wind and solar photovoltaics.