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Expansion of storage facilities for energy system transformation

The share of renewable energies has risen sharply in recent years. Efficient electricity storage systems are thus becoming increasingly relevant. Not only do they buffer the natural generation fluctuations of wind power and photovoltaics, they also help to keep the power grid in balance at all times.

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Flexible partners for the energy mix of the future

Storing significant amounts of electrical energy on demand is one of the major challenges of the energy revolution. Pumped storage power plants play a major role here: As all-rounders in the energy industry, they can store energy in large quantities and, if required, feed it back into the grid as electricity within a few seconds. In this way, they help to cover energy requirements when other supply capacities are not sufficient and provide important reserves in the event of power plant outages and high demand peaks.

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Expansion project

EnBW plans to expand the traditional Rudolf-Fettweis Plant. Even though we are still in the early stages of project development, it is important for us to provide you with comprehensive information at an early stage.

More information about the project

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EnBW Energie Baden-Württemberg
EnBW Energie Baden-Württemberg AG
Schelmenwasenstraße 15
70567 Stuttgart
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How a pumped storage power plant works

Functionality of a pumped storage power plant

The upper basin (i.e. a higher water reservoir) serves as storage. If energy is needed for a short time, the water stored in the upper basin is fed to the turbines of the turbine house in the valley. This is how the turbines drive the generators. In this way, electricity can be generated in a matter of seconds. This compensates for fluctuations in the power grid and covers power peaks. The frequency of 50 Hertz in the European interconnected grid remains stable because of the balancing of the pumped storage facilities, which react very quickly compared to other power plants.

If there is more electricity available than is currently needed, the water from the lower basin is pumped back into the upper basin. The pumps are driven by the generators, which take over the function of motors. The water is now once again available for power generation. This ability of pumped storage power plants to both absorb and release energy helps to better balance power generation and demand. This makes pumped storage power plants indispensable when it comes to reconciling ever-increasing electricity production from wind and sun with conventional power plants and the electricity requirements of consumers.

Most of the upper basins of our pumped storage power plants have natural inflows. Part of the energy produced by our pumped storage power plants is thus attributable to renewable energies. We currently operate pumped storage power plants with an installed capacity of around 1.9 Gigawatts.

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What pumped storage power plants can do

View of the upper and lower basins of the Glems pumped storage power plant
  • They store large quantities of electricity like a gigantic battery.
  • They deliver power on demand.
  • They compensate for fluctuations in the power grid and irregularities in regenerative power generation.
  • They are black-start ready – in other words: They quickly rebuild the power grid in emergencies.
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Demand is constantly increasing

EnBW wind farm Baltic 1: The first commercial offshore wind farm in Germany.

At present, pumped storage power plants are still the only truly effective option for storing electrical energy on a large scale. In view of the fact that wind and solar energy are subject to strong temporal fluctuations – and thus produce electrical energy separate from demand – additional storage options are urgently needed.

At the same time, the strong expansion of wind energy in northern Germany means that increasingly more electricity is being generated without being consumed. However, the economically strong southern German regions continue to record the highest energy demand. Because of the topographical conditions, it is precisely here that it is possible to build pumped storage power plants that could provide electricity from the North for demand-driven use in the South.

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Our expansion projects

The Rudolf-Fettweis Plant in Forbach

The Rudolf-Fettweis Plant in Forbach in the northern Black Forest was completed in the 1920s and is one of EnBW’s oldest production sites. We are currently examining an expansion and conversion of the plant. As a result, the storage volume could be increased by around two million cubic meters and the output of the power plant almost quadrupled to around 270 MW compared to today’s output.

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Schluchsee Nature Paradise

Through long-term partnerships with Vorarlberger Illwerke AG and Schluchseewerk AG, a 37.5% subsidiary of EnBW, we already have access to further large storage capacities in the form of reservoirs in the Alps and the southern Black Forest. Together with Illwerken, we are currently developing the pumped storage power plant Obervermuntwerk II. And in Atdorf, in the southern Black Forest, the Schluchseewerke are planning the construction of one of the largest pumped storage power plants in Europe with a total capacity of 1,400 MW.

Within the scope of research projects, we also test other storage technologies.

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Flexible gas storage for high supply security

Cavern storage facilities are used for peak coverage and to compensate for seasonal fluctuations in natural gas consumption. In addition, natural gas storage facilities serve to ensure security of supply by compensating for gas supply shortfalls. Together with EDF, EnBW commissioned the Etzel natural gas storage facility in October 2012.

The natural gas storage facility in Etzel stores up to 400 million standard cubic meters of natural gas. This is enough to supply around 300,000 households with natural gas for one year. If there is a bottleneck on the market, the storage facility can feed natural gas from the caverns into the gas grid within a short time with a capacity of 600,000 standard cubic meters per hour. This means that up to one million households can be supplied at the same time.

Further information about the Etzel natural gas storage facility