The Sand Battery has been developed by the Tampere-based company Polar Night Energy. It acts as a large heat storage unit and is a unique solution for storing renewable energy. District heating companies are seeking ways to reduce the amount of fuel they burn and offer residents clean district heating. Loviisan Lämpö chose Elisa's solution to optimise the operation of the Sand Battery. Elisa's solution automatically offers the Sand Battery's flexibility capacity to the electricity reserve markets maintained by Fingrid.

"Additional energy flexibility is considered crucial for the future of the energy sector. Elisa's AI-powered solution offers organisations with energy storage capabilities, such as district heating companies with thermal storage, an efficient and continuous way to be part of Elisa's flexibility resource asset fleet and operations, allowing them to benefit both economically and environmentally," says Jukka-Pekka Salmenkaita, VP of AI at Elisa.

After commissioning, Loviisan Lämpö will be able to produce more than half of its district heating using electricity. The emissions from the Pornainen district heating network will decrease by 70% from the current level, a reduction of around 160 tonnes of carbon dioxide per year.

"Burning fuels is not sustainable for the planet. A huge energy transition is underway, and Finland is investing heavily in new technologies to produce heat. In addition to storage, being able to participate in reserve markets is essential for the electrification of district heating, which Elisa is enabling us to do in Pornainen", says Liisa Naskali, COO of Polar Night Energy.

Elisa technology ensures a profitable sand battery

A key part of the profitable operation of the Sand Battery is optimising its use according to changes in electricity prices and the reserve markets. Elisa's solution automatically identifies those times when it is most profitable to heat the Sand Battery using electricity. For example, in windy weather, there may be overproduction in the electricity grid. In such cases, Fingrid will pay Loviisan Lämpö to increase the Sand Battery's electricity consumption. Conversely, if production is lower than anticipated or if a large power plant is down, the electricity consumption of the Sand Battery will be correspondingly reduced and the heat stored in it used for district heating in Pornainen.

"Elisa's role in the project is significant, as reserve market revenues will ensure that the Sand Battery is profitable. Elisa is a strong player in the reserve markets with a great track record", says Mikko Paajanen, CEO of Loviisan Lämpö.

Carbon-neutral electricity production is already significant in Finland, comprising 94% of the country's production in 2023. (Source: Energy Production - Finnish Energy) Since electricity in Finland is already among the cleanest in Europe, it makes sense and is important to continue on this path by electrifying the heating systems, which still produce a large part of Finland's greenhouse gas emissions.

However, the variable nature of renewables production poses challenges to the electricity grid, where supply and demand must always be balanced. Elisa's solution plays a significant role in balancing the electricity market by harnessing all kinds of energy storage solutions, such as thermal storage and batteries. It provides crucial flexibility for the electricity grid, while also making investments in energy storage profitable.

Elisa has extensive experience in energy optimisation for electricity markets

As a company that uses a lot of electricity itself, Elisa has been developing solutions to reduce electricity costs for years. This work has led to the development of an AI solution that optimises electricity use and participation in reserve markets according to the needs of the electricity system.

"Electricity markets have changed, and nowadays, price fluctuations are rapid, and electricity trading takes place in several marketplaces. It is no longer possible for humans to manage this complex system alone. We have developed our own AI-based optimisation technology that we are continuously developing to match developments in the changing electricity markets", says Ville Väre, Director of Business Development at Elisa.

Construction work is underway, and the steel-clad Sand Battery - 15 metres in diameter and 13 metres tall - will be commissioned in early summer. Currently, electrical, piping and equipment installation work is being carried out, and testing will begin in the spring. Polar Night Energy's Sand Battery will produce peak power even during freezing winter weather, with a power output of 1 megawatt and a storage capacity of 100 megawatt-hours. This large storage capacity allows for optimised electricity use over timescales of several days or even several weeks.

Additional information for the media: Elisa Communications, tel. +358 50 305 1605, mediadesk@elisa.fi

Press photos

More about Elisa's smart energy solutions
Elisa offers telecom operators, companies such as district heating companies, and households the opportunity to take an important and profitable role in the energy transition. Elisa's energy storage optimisation solution is based on AI and machine learning. In telecommunications networks, the technology utilises the flexibility of base station batteries to control the power supply for the base stations by optimising battery charging and discharging times. Part of this flexibility capacity is offered to transmission system operators for balancing the electricity network. The solution is also capable of utilising solar energy in addition to grid energy.

Elisa uses this technology itself in its own mobile network in Finland and has begun deploying it in the company's network in Estonia. Commercial deliveries of the solution began in 2024. DNA Tower, which builds and maintains mobile networks in Finland, has announced that it will use Elisa's technology. Ålcom, the operator in the Åland Islands, has also adopted the technology for use in its network with solar energy.

Elisa has also brought the energy solution to homes: the Elisa Kotiakku domestic battery service helps households smooth out electricity price spikes and store electricity produced by solar panels.

More about Polar Night Energy
Polar Night Energy is a Finnish startup that designs and manufactures high-temperature thermal energy storages for wind and solar energy. The Sand Battery developed by the company enables a significant increase in wind and solar energy production while reducing the use of fossil fuels. The company was founded in 2018.

More about Loviisan Lämpö
Loviisan Lämpö is a Finnish district heating company that supplies district heating to customers in the Loviisa, Pukkila, Pornainen, Pyhtää and Lappohja areas. Loviisan Lämpö is owned by CapMan Infra.