Due to the growing population the sustainable and renewable energy sources are seen as more significant for the future. With the expansion of renewable energy the storage potential of hydropower is becoming more and more important because it allows us to store energy surpluses for use in times of energy peak demand. The construction of new power plants, capacity increases or renovations of existing schemes are under consideration today. With this, options for the use of underground space are an essential element of design creating a strong need for innovative mechanized excavation solutions. This paper highlights EDF’s rehabilitation of the Romanche-Gavet hydropower plants with focus on the con-struction of the headrace tunnels to be excavated by two Open Gripper Tunnel Boring machines.