Hydraulische Auslegung und Optimierung des Kavernenspeichers des PSW Forbach

Translated title of the contribution: Hydraulic design and optimisation of the underground storage cavern of the Forbach PSP

Hannes Blindenhöfer*, Wolfgang Richter

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference paperpeer-review


In the course of the renovation and extension of the Rudolf-Fettweis hydropower plant Forbach, EnBW AG intends the construction and operation of the Forbach pumped storage plant (PSP). This includes the reconstruction of the Schwarzenbach
and the Murg hydro power plants, integrated in a new cavern power plant with extended pump storage capacity. The existing storage of the Schwarzenbach dam as upper reservoir will continue to be used. In order to increase the overall storage capacity of the Forbach PSP, an additional volume of approx.
200'000 m³ must be provided in the lower reservoir. For this, the option of an underground storage cavern was selected, which has amongst others the benefits of small ecological impacts as well as a good acceptance by the local communities.
The underground storage cavern was designed by Tractebel Engineering GmbH based on the experience of the hydraulics engineers and by applying a 1-dimensional flow simulation model. The main emphasis was on avoiding potential
air intrusion during pump operation. To avoid flow separation, which might promote the development of vortices or air intrusion, the flow resistance and tunnel slopes were studied in detail.
In a subsequent step, the underground storage cavern was reassessed by TU Graz in 1-dimensional as well as 3-dimensional numerical models and its functionality could be confirmed. In an optimization process, the hydraulic head losses at the intake bay could be reduced by 30%. Furthermore, the development
of surge waves during transient scenarios was examined and considered as uncritical.
Translated title of the contributionHydraulic design and optimisation of the underground storage cavern of the Forbach PSP
Original languageGerman
Title of host publicationWasserbau in Zeiten von Energiewende, Gewässerschutz und Klimawandel
Subtitle of host publicationStrategie und Innovation in der Wasserkraft Gewässerschutz als Herausforderung für die Wasserkraft Naturgefahren
EditorsRobert Boes
Publication statusPublished - 15 Sept 2021
EventWasserbau-Symposium 2021: Wasserbau in Zeiten von Energiewende, Gewässerschutz und Klimawandel - ETH Zürich, Zürich, Switzerland
Duration: 15 Sept 202117 Sept 2021

Publication series

NameVAW Mitteilungen
ISSN (Print)0374-0056


ConferenceWasserbau-Symposium 2021


  • Unterground pumped storage plant
  • 3D CFD
  • Transient Hydraulics
  • Energy Storage
  • Pumped-Storage Hydropower


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