Hydropower generation has a long tradition here: For more than 100 years, we and our predecessor companies have been operating pumped-storage and run-of-river power plants on the major rivers of Baden-Württemberg. These plants are a vital part of the energy supply because they can provide baseload power and are less affected by short-term weather fluctuations than weather-dependent forms of generation such as wind and solar energy. That is why we continuously invest in the maintenance and modernization of our facilities.
In Forbach, we are extensively expanding the Rudolf-Fettweis plant: Plans call for an underground cavern storage facility and a new cavern power plant located directly inside the mountain. This will further advance the technical capabilities of this historic hydropower site and, in the future, make it even better equipped to store energy flexibly and supply it as needed.
There are essentially two types of hydropower plants: run-of-river power plants and storage power plants. The technical way in which the two hydropower plants work is identical: Water is retained by a dam and channeled through one or more turbines in a controlled manner. These turbines drive generators that use the rotational energy to generate alternating current, which is then fed into the power grid.
How a pumped storage power plant works
How a a run-of-river power plant works
On the Upper Rhine between Basel and Karlsruhe, ten large hydropower plants produce around nine billion kWh of electricity annually. Iffezheim Rhine power plant is one of them and produces electricity for mathematically 250,000 households. A fifth turbine was built between 2009 and 2013, making the run-of-river power plant the largest in Germany.
Between Lake Constance and Basel, the Rhine has a gradient of 150 meters. With its strong current and laminar flow, it is ideal for generating energy for southern Baden and Switzerland. We have either a direct or indirect stake in nine of 13 hydropower plants, mainly through Energiedienst AG. These include Rheinfelden hydropower plant, the oldest and, following modernization measures in 2010, one of the most modern run-of-river power plants in Europe.
The many smaller rivers in Baden-Württemberg also provide us with a reliable supply of renewable electricity. On the Iller River, we operate five run-of-river power plants with a total capacity of about 47 MW, which can theoretically supply electricity to mathematically 54,000 households annually. The Iller’s flow rate fluctuates greatly. During the snowmelt and during floods, the river can carry up to 900 m³/s. At these times, the weirs are staffed around the clock.
Forbach hydropower plant is exceptional in many respects. In addition to its traditional history, it can be described as a run-of-river, storage and pumped storage power plant. This is due to the considerable differences in elevation, an optimal water supply and topographically ideal conditions for reservoirs. The location is currently undergoing extensive modernization, with a cavern storage facility and an underground power plant being built. This is set to almost double the storage volume.
Glems pumped storage power plant is situated on the edge of the Swabian Alb. Due to the steep rise in the terrain between the artificially created upper reservoir and the turbine hall, the pumped storage power plant can use an elevation difference, or head, of almost 300 m.
On the Neckar River, we operate and maintain a total of 27 hydroelectric power plants with a combined capacity of 93 MW. Twenty-four of these plants are owned by Neckar AG, an 82% subsidiary of EnBW. Over its 200-kilometer stretch, the Neckar River overcomes a total elevation difference of approximately 160 meters.
EnBW has a 37.5% stake in Schluchseewerk AG, which has its headquarters in Laufenburg and is one of the largest operators of pumped storage power plants in Europe. Five power plants, including two underground power plants, generate around 2.2 billion kWh each year. The hydropower plants in the southern Black Forest are largely powered by water from the Schluchsee reservoir and some Black Forest streams.
Vorarlberger Illwerke AG has ten hydropower plants, four reservoirs and several diurnal reservoirs in the Montafon and Walgau valleys. The company is based in Bregenz and is an electricity supplier and contractual partner of EnBW.
The hydropower plant in Rheinhausen has been in operation since 2024 and is one of the most modern plants of its kind. It covers the annual electricity needs of mathematically about 250 households. It is unique in that local authorities are also involved in the plant through the company “Klima vernetzt Südbaden GmbH & Co. KG”.