Short-term storage reduces the need for backup power plants

28.10.2025

Source: E & M powernews

According to an analysis by Ecostor, short-term storage systems can significantly increase the security of supply during dark doldrums and noticeably reduce the need for fossil reserve power.

Battery storage systems can stabilize the power supply in Germany, even during dark doldrums with little sun and wind. This is shown by an analysis carried out by the company "ECO STOR" from Kirchheim near Munich on October 28. The study is based on an energy-economic optimization model called "PyPSA", which takes into account real weather and generation data over several years.

According to the model, just 60,000 MW of installed short-term storage with a capacity of two to four hours could reduce the need for secured backup power by 15,000 to 20,000 MW. If the installed storage capacity increased to 100 GW, the demand would be reduced by up to 24,000 MW.

The model depicts the interaction of wind energy, photovoltaics, battery storage and controllable power plants in the German electricity system. The analysis was based on the German government's expansion target for 2030 with a high proportion of renewable energies. The aim was to determine the influence of different storage capacities on the required reserve capacity.

Making the energy transition more efficient

"Reliable large-scale battery storage systems are the key to greater cost efficiency in the energy transition," says Ecostor Managing Director Georg Gallmetzer. "If we exploit this flexibility potential, we can dispense with up to 30,000 MW of backup power plants. This makes the energy system more robust and reduces overall costs."

Short-term storage compensates for short-term fluctuations in the electricity grid and reduces peaks in the residual load. This reduces the need for fossil or controllable power plants. For longer phases without wind and sun, supplementary solutions such as long-term storage, electricity exchange with neighboring countries or flexible demand are required.

Online tool for energy transition scenarios

Gallmetzer emphasizes that there are still many preconceptions about large-scale storage systems. However, the data clearly shows that large-scale storage systems can economically and reliably replace up to 30 percent of the backup power plants required. "They stabilize the grid on a daily basis and increase the efficiency of the electricity system," says Gallmetzer.
The benefits are particularly great in the early phases of storage expansion. Even small installed capacities significantly increase the flexibility of the electricity system. With increasing expansion, the need for fossil reserve capacity decreases further.

With the analysis and a freely accessible online tool, Ecostor aims to make the discussion about the role of storage in the energy transition more objective. The interactive model enables users to simulate their own scenarios for wind energy, photovoltaics, storage capacity and electricity demand and understand their influence on the residual load.

The complete Ecostor analysis is available for download as a PDF.

Author: Susanne Harmsen