Rehabilitation and Repair

Update on renovation of 27 MW Robbia hydropower plant in Switzerland

Update on renovation of 27 MW Robbia hydropower plant in Switzerland
(photo courtesy Repower AG)

Repower AG reports that there is one year left until completion of the repowering of its 27 MW Robbia hydropower plant in Valposchiavo, Switzerland.

The Robbia power plant is located near San Carlo and Raviscè. The power plant building consists of a machine hall (main building), several technical and storage rooms, an operations office (southern extension) and a storage room above the distribution lines (northern extension). The center is equipped with four horizontal-axis machine groups. Turbine water is discharged into the Poschiavino through a double-guided underwater channel that is now mostly open.

The Robbia hydroelectric power station marked the start of the use of hydropower at the upper level in Poschiavo. Construction of the Robbia hydroelectric power station lasted from 1909 to 1911. In 1910 the first machine group went into operation. It subsequently triggered the construction of the Palü and Cavaglia power plants. In 1921, machine group 3, which is still in operation today, was installed.

From 1940 to 1945, the Robbia power plant was expanded, including the headrace. Installation of today’s machine group 1 was completed. In addition, the Lagobianco dam was raised and the Palü pumping station was built. In 1956, machine group 2 was deployed. Since then, the system design and disposition of the Robbia power plant have remained unchanged.

Now, the facility is being completely renovated, and Repower said gross investments of around CHF125 million (US$138.2 million) are planned. Work on this rehabilitation began in mid-2020 and is scheduled to be complete in mid-2024.

Significant renovation and expansion work is planned for the reliable continued operation of the Robbia power plant, Repower said. Around 90% of the system will be renewed. Almost the entire power plant building will be hollowed out and the components replaced. The complete replacement of the machine groups with three identical machine sets is planned. The crane system must also be completely renewed and adapted to the specifications (assembled weight, lifting height) of the new machine groups. With this replacement, the distribution pipeline and the ball valves of the machines are also replaced. Due to the changed mechanical dimensions and forces, the foundations and the connection to the underwater channel have to be redesigned for each machine.

At the same time, optimization of the headrace system is planned. This includes minimizing hydraulic losses and optimizing the use of process water. Among other things, the storage volume of the Puntalta Reservoir will be expanded and the existing Balbalera pressure line with its two separate pressure pipes will be replaced by a single larger pressure line.

Repower is a sales and service company in the energy sector. The group is active along the entire electricity value chain, from production and trading to distribution and sales, as well as in the gas business.