By Lynda Myer
In order to conversing a storage and run-of-river power plant to a pumped storage power plant in Germany, the Lot 2 civil works contract has been awarded to Porr.
As a part of a €280m investment by EnBW Energie Baden-Württemberg to convert and expand the Rudolf Fettweis Plant in Forbach, in the Black Forest, this contract’s value is €98.3m (US$107m).
Building of mined caverns, water reservoirs and tunnels, the shell of the power plant cavern, construction of two pressure shafts, as well as foundation engineering work, are the subsets of Lot 2. The blasting and excavation process of huge cavities and tunnels in the rock is due to be implemented before that the new power plant can go into operation in 2027. An estimated 450,000m3 of rock excavation material will be produced.
Although the whole length of the tunnel system is 5.2km, using the raise-boring method almost 510m of shafts will be constructed and the main tunnel alone is going to have a length of 946m and a cross-section of up to 71.72m2, whereas there will be six side tunnels as well as access tunnels, supply tunnels and tunnels for energy transmission. Additionally, the volume of the underground water reservoirs is 200 million liters.
The scheduled date for commencing the construction process is autumn this year.
Porr has experience in building pumped storage power plants, such as Limberg III in Kaprun.
According to Karl-Heinz Strauss, CEO of Porr AG: “Pumped storage power plants are a particularly effective solution for generating alternative energy. They are therefore an important building block for the energy transition.”
Being launched in 1914, the heritage-protected Forbach run-of-river power plant will be transformed to a pumped storage power plant that will remarkably increase its efficiency. Until now, after the water from the Schwarzenbach and Murg dams passed the turbines, it flowed into an equalization basin and then into the Murg. The new underground sub-basin will serve as an indirect power reservoir and from there the water can be circulated as often as required.
