130. The Three-Chamber Surge Tank, New Concept for the Downstream Conduit of Pumped-Storage Schemes

Changing conditions in the European power market have led to an increase in the demand for peak energy. Shorter response times and an increase in the frequency of load changes for pumped-storage facilities imply the need for an improved “surge tank strategy”. The three-chamber surge tank with two separate water-carrying lower chambers is an entirely new concept for the downstream portions of pumped-storage schemes. By splitting and then reuniting the water column within the system of water conduits, this type of surge tank can reconcile contradicting design criteria, while offering substantial cost advantages over conventional surge-tank types. This paper describes the main features of the three-chamber surge tank, which is being developed at the Department of Hydraulic Engineering and Water Resources Management of the Graz University of Technology. Water-surface level results obtained by use of a calculation method developed to meet the special requirements of this system will be presented; the savings in tunnel volume (possibly also in shaft volume for the power station) will be compared with conventional designs.