The City of Lappeenranta is testing an energy storage system at the Selkäharju heating centre. This is a heat accumulator system that started testing in Mustola, Lappeenranta, in 2019, but was discontinued in January 2022 when the energy crisis made changes to the district heating network. Testing was moved from Mustola to Selkäharju, and the storage modules changed from salt-based to metal-based.
The city continues testing the thermal battery, as the challenge for the future energy system is uneven production. Energy is projected to be available in excess of demand, but production is dependent on weather conditions. This will lead to an increase in the daily variability of electricity prices. To achieve this balance, energy storage solutions are needed to better match energy supply and demand.
Storing energy as heat is cheaper than storing it as electricity. At the same time, much of the energy demand is for thermal energy. The thermal battery will test the viability of storing electricity directly as heat, as well as the potential for replacing fossil energy with renewable electricity. In Selkäharju, the heat accumulator would replace natural gas and is estimated to reduce carbon dioxide emissions by more than 300 tCO2e, says Miika Alatalo, a city expert.
- The heat accumulator will enable the replacement of heat-generating fuels such as natural gas and light fuel oil with electricity. This reduces carbon emissions, as well as dependence on imported fuels.
- As charging and discharging are independent of each other, the technology also creates demand elasticity in the electricity market.
The Selkäharju thermal battery will be built and testing has started in 2023, with a pilot project in cooperation with energy company Lappeenranta Energia Oy.
The storage battery will be charged with electricity in high-temperature storage modules, from which the energy will be discharged as heat to the point of use. A similar device has already been in use in industry since 2021, where the heat has been used to produce process steam. Now the use of the device is being tested in district heat production.
The heat storage system has been developed by Elstor Oy, a Lappeenranta-based company that has sought to create a cost-effective and practical solution for low-emission and low-cost energy production. The device can also be used as a load for balancing the electricity grid. The test run will verify the behaviour of the device and calculate the impact on energy costs and CO2 emission reductions. If the energy storage of the thermal battery meets the expectations set, it will have a large market in Finland and globally.
The experiment is part of the Towards Carbon Neutral Municipalities and Regions project, which is part of the EU's six-year LIFE programme implementing national climate policy.
For more information:
Miika Alatalo, Expert,
040 759 6695, miika.alatalo@lappeenranta.fi
Ilkka Räsänen, Environment Director,
040 081 5284, ilkka.rasanen@lappeenranta.fi