The 360MW Obervermunt II pumped storage plant in Montafon, Austria, has officially opened, marking another milestone in the partnership between EnBW Energie Baden-Württemberg AG and Vorarlberger Illwerke (VIW).

Obervermunt II was built over four and a half years and utilizes two turbines and two pumps. The plant uses the existing reservoirs, Lake Silvretta and Lake Vermunt, which also continue to be used by the storage power plant Obervermunt I (36MW) that was built in the 1940s.

The cavern power plant (height 33m, width 25m, length 123m) is located at the end of an 800m-long tunnel inside the Silvretta Massif. The cavern is the starting point of the about 3km-long underground Silvretta gallery (excavated diameter almost 8m) and part of a complex tunnel and gallery system up to Lake Silvretta at Bielerhöhe – the highest point of the well-known Silvretta High Alpine Road.

EnBW and VIW have worked closely together for nearly 100 years. In addition to a long-term electricity procurement agreement which most recently was renewed until 2041 and to EnBW’s use of VIW’s power plants, this also includes collaboration in new construction projects.

With Obervermuntwerk II, the Rellswerk plant – a smaller facility which was commissioned in 2017 – and the Kopswerk II plant (525MW, commissioned in 2008) VIW and EnBW have now jointly carried out three pumped storage projects over the course of the past ten years.

“Together with our partner of many years we are happy about the successful completion of the project. Given the significance of storage technologies for system stability and security of supply, they will continue to be an integral part of the energy supply in Europe in the future. This applies to pumped storage power plants as well as, increasingly, the new storage technologies,” explained EnBW Chief Technical Officer Hans-Josef Zimmer. “With Obervermunt II we are once again considerably expanding our pumped storage capacities and can now store even more electricity from renewable sources, such as wind and solar energy. This is another important step for us towards making the Energiewende a reality.”

Due to their enormous significance for system stability and the security of supply, storage technologies are an integral part of EnBW’s portfolio. The company continues to advance plans for upgrading the Rudolf Fettweis plant at its Forbach site into a modern and powerful pumped storage power plant. In January 2018 an application for approval was submitted to the Regional Administrative Authority in Karlsruhe. The final investment decision for the new downstream power station can only be taken on the basis of a planning approval and an examination of the general energy-industry-related conditions.