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.