The construction project for the energy storage at PVO-Vesivoima's Kierikki power plant has been completed. The company's first, in total a three-megawatt ultracapacitor has been installed and commissioned. The project, located in the area of the Kierikki hydropower plant on the river Iijoki, pilots energy storage technology that meets short-term adjustment needs and extends the lifespan of the power plant. The piloted ultracapacitor will gather important data and user experience for future investment plans.
Construction work on the ultracapacitor began in autumn 2024. During the autumn, two shipping containers were installed near the power plant’s switchyard, each containing energy storage systems with a capacity of 1.5 megawatts implemented with ultracapacitors.
“This is an important pilot project for us. We will get first-hand information on how the energy storage works as part of the hydropower plant, which produces balancing power for the electricity market and also participates in the frequency control of the electricity grid,” says Markus Pyykönen, the Project Manager at Pohjolan Voima.
The ultracapacitor piloted in Kierikki will gather practical experience for possible larger investments.
“We expect to gain practical experience and information on the results by the end of this year. The project in Kierikki already has a reservation to expand the energy storage to double its size. Other hydropower plants would then follow,” says Antti-Pekka Sipola, Operations and Development Manager at PVO-Vesivoima.
In addition to the ultracapacitor, the project at the Kierikki hydropower plant has received the latest improved version of the turbine governor developed jointly by PVO-Vesivoima and the University of Oulu.
“The improved features of the turbine governor have been implemented in the control of the ultracapacitor energy storage. When working together, the turbine governor, turbines, and energy storage form a system that can regulate the frequency of the electricity grid more efficiently and automatically. Cost-effectiveness improves, and at the same time, the system extends the lifespan of the turbines – it lengthens as the mechanical stress on the turbines caused by regulation decreases,” explains Sipola.
The ultracapacitor system was supplied by the German company Freqcon GmbH. The Finnish company Insta Automation Oy supplied the main electrical systems for the energy storage, the new main transformer, and related electrical work.
Ultracapacitor meets growing demand for adjustment power
The share of renewable energy production, which varies with the weather, and especially wind power, has increased significantly, leading to increased demand for balancing power.
The ultracapacitor is a highly efficient short-term energy storage system operating in conjunction with hydropower. It is an electrostatic device whose power can be accessed in less than a second without significant loss of charge capacity. The solution is needed when the supply of electricity in the grid suddenly changes: the ultracapacitor stores electricity and releases it quickly into the grid for a few minutes.
The ultracapacitor improves the performance and balancing power use of hydropower. Together with the hydropower plant, the energy storage supports the reliability and operational security of the electricity system by strengthening the ability to produce the balancing power needed for the growth of renewable energy in a timely manner.
In addition to improving balancing capability, the ultracapacitor also extends the lifespan of the hydropower plant in the long term, as it reduces the very rapid control needs and wear of the equipment.
The ultracapacitor also supports the increase in renewable energy production.
Further Information:
Markus Pyykönen, Production Development Manager, Pohjolan Voima Oyj, tel. 040 840 2428, markus.pyykonen@pvo.fi
Antti-Pekka Sipola, Operations and Development Manager, PVO-Vesivoima Oy, tel. 050 303 8615,
antti-pekka.sipola@pvo.fi