How do we secure energy supply in times of crisis? In Grums, Sweden, a battery storage system is now being tested to keep schools, preschools, and other vital public services running—even if the national power grid goes down. The project could become a key to a more resilient electricity system.
In Grums, Värmland, a large battery storage facility is currently used commercially to operate on the frequency market and stabilize the power grid. But now, researchers at RISE are investigating whether the battery could also play a vital role in Sweden’s emergency preparedness.
"The frequency market has become more profitable in recent years, which has driven many investments in battery storage. Now we want to see if they can be used as a resource to strengthen resilience," says Hampus Piehl, project manager and research and development engineer at RISE.
The goal is to use the battery for so-called island operation—creating a local power grid that continues to function even if the main grid goes down. This could keep electricity flowing to designated municipal resilience hubs such as schools, preschools, or sports halls. These are places where people can gather and access electricity to cook food or receive important information.
Today, Sweden relies on a large interconnected power grid. But if parts of the grid are disrupted—for example, due to cyberattacks—local battery storage systems could become an important emergency resource
"Today, Sweden relies on a large interconnected power grid. But if parts of the grid are disrupted, for example due to cyberattacks, local battery storage systems could become an important emergency resource," explains Hampus Piehl.
Calculations show that the battery in Grums could keep a preschool running for nearly a month, a school for about a week, and the ice rink for roughly a day.
Technical and financial challenges
Many battery storage systems in Sweden are currently designed to operate on the frequency market—that is, for commercial use—and are not prepared for island operation. To power a local grid, a battery requires specific capabilities that allow it to independently control voltage and frequency.
"Such compatibility isn’t standard today, and through the project in Grums, we want to explore how existing battery storage systems can be equipped with these functions," says Hampus Piehl.
The project is also examining the possibility of connecting renewable energy sources, such as solar panels or local hydropower plants, to the battery system. This could extend the duration a local grid can remain operational, but it involves technical challenges like synchronizing voltage and frequency between different sources of generation.
"Utilizing existing battery storage systems for island operation could strengthen Sweden’s emergency preparedness. Today, we see that few systems are equipped for this, but the potential to run local grids using battery storage and local energy production exists in many places across the country."
About the project "The Role of Battery Storage in Future Fossil-Free Emergency Preparedness Measures'"
- Funded by the Swedish Energy Agency
- Ongoing until December 2026
- Led by RISE in collaboration with the energy company Ellevio and the municipality of Grums
- The battery storage facility in Grums is owned by Ellevio Energy Solutions and has an energy capacity of approximately 10 MWh and a power output of 10 MW
