If Lithuania has Kruonis, why does it need battery parks?

The principle behind Kruonis is straightforward. It uses electricity to pump water into an upper reservoir. When energy is needed, the water flows down through turbines, driving generators that return electricity to the grid.

Kruonis is therefore an energy storage facility. A battery park performs the same basic task in a different way: energy is stored in electrochemical cells, while power electronics control charging and discharging.

The electricity system has different tasks to address. At one moment, it needs to supply large amounts of energy for several hours. At another, it needs a rapid, precise adjustment to the difference between generation and consumption.

Kruonis offers large scale and sustained energy delivery. Its four units have a combined capacity of 900 MW. According to Ignitis Gamyba, the plant can deliver that power for up to 12 hours. It also provides frequency restoration reserve, voltage regulation and services to prevent system emergencies. Its role therefore extends well beyond buying electricity at a lower price and selling it at a higher one.

A strength of battery parks is their rapid and precise response, controlled through power electronics. Appropriately designed systems can promptly adjust charging or discharging power and provide frequency control services. A brief power adjustment does not necessarily require many hours of stored energy.

Pumped-storage technology is also being improved. A fifth, 110 MW unit is being installed at Kruonis, which is expected to broaden the plant’s ability to adjust power and provide system services.

Ignitis Group emphasises that the new unit will offer greater flexibility in both generation and pumping modes. This matters as variable solar and wind generation increases.

On 12 August 2026, Ignitis Group reported that approximately 80% of the fifth-unit project had been completed. Construction of the unit was still continuing.

In May 2026, Ignitis Gamyba announced that the first shipment of equipment for the new battery system had arrived at the Kruonis site. The park under development will have 99.2 MW of power capacity and 198.5 MWh of energy capacity. Full completion is planned for 2027. In a newer announcement on 12 August 2026, Ignitis Group reported that battery deliveries at Kruonis had been completed. Completing equipment deliveries does not mean that the entire park has started operating.

This example shows how a large pumped-storage power plant and batteries can be developed alongside each other. Combining them provides additional flexibility and helps integrate more renewable electricity generation.

A pumped-storage plant needs suitable terrain, large bodies of water and complex infrastructure. Battery systems can be installed in projects of different sizes and closer to particular generation or consumption sites. They still require an appropriate grid connection and controls.

Some services provided by hydroelectric plants and batteries overlap in the balancing market: they can compete in the same auctions. However, the needs of the whole system depend on more than the total number of installed megawatts. The type of service, response, duration, location and power available at the time all matter.

So the question “why batteries if we have Kruonis?” has a practical answer: the electricity system benefits from a variety of complementary sources of flexibility. Kruonis itself, expanding with both a new hydro unit and batteries, is a concrete example of this combination.