Storing significant amounts of energy on demand is one of the major challenges of the energy revolution. Pumped storage power plants can make a major contribution to this: As all-rounders in the energy industry, they can store large quantities of energy and feed it back into the grid at short notice if required. They may also provide other important network services. That is why we are planning to expand our traditional Rudolf-Fettweis Plant.
The Rudolf-Fettweis Plant in Forbach
The Rudolf-Fettweis Plant in Forbach has great potential to increase storage capacity and thus contribute to the energy revolution. We have therefore developed a concept to expand the existing facility into a modern, high-performance pumped storage power plant. Even if no investment decision has yet been made, it is important for us to continue to provide you with comprehensive information about our expansion plans at an early stage.
The run-of-river, storage, and pumped storage power plant consists of four individual power plants built between 1914 and 1926. The main components of the Schwarzenbach plant are the Schwarzenbach reservoir – a reservoir with a volume of 14 million cubic metres and which is fed by several natural tributaries – the machine house in Forbach – in which the turbines and generators are housed – and the equalising reservoir in Forbach via which the water coming from the Schwarzenbach reservoir drains into the debris flow after energy generation in the power house.
A cavern storage facility is to be added to the Forbach equalising reservoir.
The Rudolf-Fettweis Plant in Forbach
Expansion of the plant – more storage volume for Forbach
Forbach offers ideal conditions for expanding the site: The lower reservoir of the future lower stage (Schwarzenbach plant) – the equalising reservoir in Forbach – is to be extended by an underground water reservoir in the form of a cavern (tunnel system) and the Schwarzenbach plant itself into a real pumped storage power plant.
The expansion plans provide for the construction of both the new Schwarzenbach power plant and the existing Murgwerk in a cavern in the mountain. The impact on the environment and the population during construction and operation can thus be minimised.
The expansion of the equalising reservoir in Forbach to include a cavern storage facility means an additional storage volume and thus a significant increase in possible turbine operation. Likewise, the new lower stage and the Schwarzenbach reservoir as upper reservoir can now be used as a real pumped storage power plant. The water can be pumped back and forth as required by the new power plant technology as well as the new water reservoir. In contrast, the water is pumped from Kirschbaumwasen to the higher Schwarzenbach reservoir for storage. From there, the water can be fed to the turbines in the valley to generate electricity. It is not possible to pump back from the equalising tank into the upper tank.
The existing 110 kV line is sufficient for the current discharge from the Murgtal.
Parallel to the project of the new lower stage, there are plans to build a completely new upper stage above the Schwarzenbach reservoir. The Schwarzenbachtal reservoir acts as a lower basin and is in exchange for the new upper basin to be built. Of the surrounding mountain ranges, the Seekopf was determined as a preferred alternative in the regional planning procedure. The expansion with a new upper and lower basin will enable the output in Forbach to be increased by around 220 megawatts (MW) and thus quadrupled.
Because EnBW wants to bring planning forward to the new lower stage, the planning for the new upper stage has been postponed for the time being.
Cavern power plants and storage facilities could look like this: Schematic longitudinal section of the new lower stage along the waterway
The possible alternatives for a new upper basin could look like this
The possible alternatives for a new upper basin could look like this: Schematic longitudinal section of the new upper stage along the waterway