Electricity storage

Rapid power balancing with batteries at hydropower plants

Wind and solar power contribute to fossil-free electricity production but also create challenges for the electricity system as production varies depending on the weather. This is where our new battery solutions play an important role in balancing the system. By integrating large-scale battery solutions into our hydropower plants, Uniper can provide a reliable and rapid response to frequency deviations, thereby ensuring a secure and stable electricity supply.

In electricity area 2 (Ångermanland and Jämtland), we have installed battery systems with a capacity of 57 MW. In electricity area 4 (Halland), there is an additional 6 MW battery system.

The technology makes it possible to deliver an immediate response to disruptions, often within a second, while the hydroelectric power plant takes over the more long-term and energy-intensive regulation. By combining the inertia (rotational energy) of hydropower with the lightning-fast response of batteries, we get a cost-effective and stable system solution without the need for excessive battery capacity.
 

The technology in brief

In short, the technology can be described as follows: if there is a disruption or imbalance in the electricity system, the battery facility will respond immediately, within a second. In this way, the power system can maintain a stable operating condition. In the event of prolonged imbalances, the hydroelectric power plant will take over and provide the greater energy output. Together, this is a cost-effective solution, as it does not require large batteries but still provides a system that offers both fast and stable frequency regulation.

How does the power system work?

For the electricity system to function optimally, rotational energy is needed. Rotational energy is the stored kinetic energy in the rotating masses of an electrical system. The rotating masses consist mainly of synchronous generators, for example in nuclear and hydroelectric power plants. Rotational energy contributes to the system's ability to withstand frequency changes. But if a production source is disconnected, let's say several wind farms stop, at the same time as the amount of rotational energy in the power system is low, this causes a large and immediate frequency change. Operating situations with low rotational energy are becoming increasingly common in the Nordic power system, as more and more solar and wind power plants are being added. The new battery installations in hydroelectric power plants will be a way to secure stable fossil-free energy for future generations.

Practical advantages

• Fast response: Batteries can handle frequency deviations within seconds, which is important when more and more weather-dependent energy sources are connected to the system.
• Effective collaboration: Hydropower provides energy storage, while the battery delivers rapid regulation without the need for large quantities of batteries
• High stability: The interaction strengthens the resilience of the electricity system and improves the quality of electricity, while counteracting the risk of power outages
• Climate-smart solutions: The technology supports the transition to fossil-free energy with reliable support services for the electricity system