Pumped-storage integrates renewable energy into the grid

The importance of electricity storage facilities is increasing. This is because the greater the percentage of renewable energy sources, the greater the fluctuations in the grid will be: Wind and solar energy do not deliver constant quantities of energy. Pumped-storage power plants (PSP) help

to adapt the supply system to renewable sources. That is why the Deutsche Energie-Agentur (dena), the German Energy Agency, advocates the profitable operation of pumped-storage plants.

Statistics & facts

Installed capacity of all pumped-storage plants in Germany.
Megawatts of net capacity are currently available to the Ger
electric power system via pumped-storage plants.
99 %
of the worldwide storage capacity
for electricity is covered by pumped-storage plants.
Terrawatt hours
Electricity stored in German pumped-storage plants in 2015.

Hydroelectric power as electricity storage


Pumped-storage power plants utilise hydroelectric power to store electricity in periods with low demand, but also in periods where excess energy is generated from renewable energy sources. By doing so, they help to balance out the fluctuating energy quantities from renewable sources. However, whether they can be operated profitably depends on the creation of suitable basic conditions.

With the growing percentage of renewable energy sources, the degree of fluctuation in electricity grids also increases, as wind and solar power do not deliver constant quantities of energy. In order to be able to operate a stable electricity supply system despite this, the grid needs to become more flexible. Above all, storage solutions are needed in order to harmonise supply and demand on the electricity market.

How pumped-storage facilities work

Pumped-storage plants (PSP) are currently the only technology that can store electricity on a large scale. They store electrical energy in times of low demand by pumping water to a higher altitude. In periods with high demand for electricity, the water is allowed to flow back down through turbines, thereby producing electrical power using generators, which is then fed into the grid.

PSPs secure supply

Apart from balancing out supply and demand, PSPs also fulfil other important roles for the electric power system. Because they allow for rapid changes in output, they can assist the grid when deviations from prognoses and malfunctions occur. Because of this, PSPs are a guarantee for grid stability and security of supply, even in emergencies: Most pumped-storage facilities are characterised by the fact that, in the case of a grid failure, they can quickly be put into operation from a switched-off state without requiring any external electricity supply.

Disincentive: Double the grid fees

However, based on the current regulatory framework, the profitable operation of PSPs is only possible to a limited extent. The prevailing electricity grid fee schedule in Germany makes it difficult to profitably operate PSPs, as their operators are obliged to pay end consumer fees. Over the entire pumped-storage process, grid fees have to be paid twice. The PSP pays grid fees when drawing electricity for pump operation as an end consumer even though the final buyer also pays grid utilisation fees for the electricity from the PSP, which in this case plays the role of a power plant feeding electricity into the grid. Politicians are called upon to find a swift solution to this problem. This is because there is a long lead time before a PSP can be put into operation: If project planning were to begin today, the power plant would only be able to begin operations in 10 to 20 years.

Platform for Pumped-Storage Plants

Due to its increasing significance for the integration of renewable energy into the electricity market, dena is actively promoting the increased use of PSPs. Together with industry partners, it has founded the Platform for Pumped-Storage Plants to come up with sophisticated proposals for integrating PSPs into the energy system. A report (PDF | 168 KB) released by the platform highlights the benefits of pumped-storage plants for the energy transition.

Our projects

Platform for Pumped-Storage Plants

Pumped-storage plants play a key role in the expansion and integration of renewable energy sources. However, in the context of the current framework conditions, their economic operation is in doubt.


  • 10 project partners
  • Stakeholders from 3 countries: Germany, Austria, and Switzerland
  • Project since 2013