Geomechanics and Tunnelling 1/2015: Surge tanks for high head hydropower plants - Hydraulic layout – New developments

High head hydropower plants can generate high electrical power at very short notice, or if equipped with pumps can also draw electricity from the distribution grid and store its energy very efficiently. In this way, hydropower plants can make an indispensable contribution to regulating the grid and the use of regenerative energy sources. Physically, this requires reservoirs at various altitudes connected through headraces.

In order to be able to use high head hydropower plants with longer headrace tunnels for the generation of electricity, surge tanks are needed to compensate the kinetic energy. A surge tank thus represents an interface between civil, mechanical and electrical engineering. The construction of new high head plants and particularly of pumped storage schemes, exploiting ever greater quantities of water and with increasingly stringent demands for flexibility, leads to additional criteria and requirements, which are explained in this article. The article describes also some specific designs of surge tanks in Austria.