Hydropower is currently the world’s most important source of electricity from renewable energies. It can meet base load requirements and, unlike wind power and PV, is not as reliant on climatic conditions. EnBW has long relied on this form of climate-friendly energy generation and has an above-average share of hydropower in its energy mix throughout Germany.
Hydropower is the oldest renewable energy source. We are using the climate-friendly type of storage and realizing a unique project by expanding our hydropower plant in Forbach, where a cavern storage facility and an underground power plant are being built.
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 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. EnBW has 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 supply us with reliable carbon-free electricity. We operate five run-of-river power plants on the Iller with an output of around 47 MW, supplying electricity to around 54,000 households annually. The Iller’s water levels fluctuate massively. During snowmelt and periods of flooding, the river discharge rate can be as high as 900 m³/s. Fire crews are busy round the clock during this period.
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.
EnBW operates and maintains a total of 27 hydropower plants on the Neckar, with 24 of these plants owned by Neckar AG, a subsidiary of EnBW in which it has an 82% stake. The Neckar overcomes a total difference in elevation of around 160 meters over the course of the 200-kilometer section. With an installed output of 93 MW, around 330,000 people can be supplied with electricity while cutting carbon emissions by around 490,000 metric tons.
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.
Our joint venture with the Turkish conglomerate Borusan Enerij operates a 50 MW hydropower plant in northeastern Turkey. Turkey has considerable untapped renewable energy potential, but we are monitoring political and economic developments in Turkey very carefully.
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 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”.