Ball pump storage

A spherical pump storage is a concept of a storage power plant type , which is supposed to enable the storage of energy in the vicinity of offshore wind farms.

The basic idea is, on the bottom of a water body to be installed in up to 700 m depth of hollow spheres made of concrete with about 30 m in diameter. If there is an excess of electrical power in the network, the water is pumped out of the hollow sphere (creating a negative pressure corresponding to the water vapor pressure ). When electricity is required, water is allowed to flow back into the hollow sphere and thus drives a turbine with a connected generator . As with conventional pumped storage power plants, the efficiency should be approx. 75% to 80%. Both the power and the amount of energy that can be stored depend on the volume and immersion depth of the hollow sphere.

Test facility in Lake Constance

In order to gain practical experience, a test of the Fraunhofer Institute for Wind Energy and Energy System Technology in Kassel with a hollow sphere three meters in diameter at a water depth of 100 meters was carried out in Lake Constance between November 2016 and March 2017 . This test was positive and confirmed the calculations. Before the system is put into practical use, a much larger concrete ball is to be sunk in the sea - either off Norway or southern Europe - in a further experiment. According to preliminary calculations, each hollow sphere with a diameter of 30 meters should be able to store 20  MWh of energy. This corresponds to the energy that an offshore wind turbine can produce in four hours. A disadvantage, however, is that the depth required for the hollow sphere is around 700 m, but offshore wind turbines are preferably set up in shallow waters .

Film documentaries

• SWR: Background to the spherical pump storage facility on Lake Constance

Web links

• Research on energy storage: Research initiative of the German government
• haute-innovation.com: Ball pump storage
• ingenieur.de: Test run at a depth of 100 m: Concrete ball used to store electricity is sunk in Lake Constance

Individual evidence

1. ↑ Nadine Kleber: Concrete balls in Lake Constance are supposed to store wind power. In: ingenieur.de. VDI Verlag GmbH, September 6, 2018, accessed on November 6, 2018 . 
2. ↑ spiegel.de: Pump storage: Researchers are planning wind power batteries on the ocean floor , accessed on February 23, 2016
3. ↑ forschung-energiespeicher.info: Ball pump storage under water , accessed on February 27, 2016
4. ↑ spiegel.de: Successful test in Lake Constance: Huge concrete ball stores energy , accessed on March 4, 2017
5. ↑ heise.de: Researchers store electricity in Lake Constance with a concrete ball , accessed on March 4, 2017