Construction work will begin in 2012 on a new pumped storage plant next to the existing Waldeck 2 facility. Work is expected to take four years, with the new capacity entering service in 2016. Planned investments for the project total about €250M.

E.ON filed the necessary applications and consents documents with the Hesse state government in Kassel in late December and expects the project to be approved later this year.

“Powerful, highly efficient pumped-storage hydro stations play a key role in making Germany’s energy supply reliable and flexible,” said E.ON Energie CEO Dr. Ingo Luge. “Pumped-storage stations are superbly suited to balancing out the intermittent output of renewables because they can store energy very efficiently and come onstream at a moment’s notice to supply zero-carbon, environmentally friendly electricity.”

The Waldeck site is ideal for building new capacity because of the existing facility and infrastructure. The new plant, including the penstock pipes and generating equipment, will be built completely underground. It will be built directly next to Waldeck pumped-storage hydro station and use the same access tunnel. The reservoirs for the new plant already exist. The volume of Waldeck 2’s upper reservoir will be increased by about 10% by raising its retaining walls. The next plant will use Waldeck’s existing, on-site switching yard to deliver power onto the network.

When the new plant becomes operational in 2016, Waldeck will have a total of 920MW of flexible capacity for generating power and for storing power that is not needed when it is produced. This is equal to about 15% of Germany’s total pumped storage capacity.

“Enlarging Waldeck pumped-storage hydro station underscores E.ON’s ambitious plans for supporting renewables growth in Germany. Renewables can only begin to realize their full potential when they work in tandem with flexible energy-storage systems like pumped-storage hydro stations,” Luge added.

E.ON is one of Germany and Europe’s biggest hydro operators, with 212 facilities in four countries and total installed hydro capacity of nearly 6.2GW.