Finland Inaugurated World’s Largest Sand Battery; Elisa Industriq’s AI Optimizes It

The inauguration was more than a technical showcase. It proved that the future of energy is green, flexible, and financially sound. Guests toured the towering Sand Battery, which has been operating since June as the main heat source for Pornainen’s district heating network. The system is expected to reduce local heating emissions by about 70% by lowering the need for a traditional biofuel boiler and entirely eliminating the use of oil. Sand Battery has a capacity of 100 MWh and a power rating of 1 MW, meaning it can theoretically supply heat at full output roughly a week in winter and up to a month during summer.

Jukka-Pekka Salmenkaita, Elisa Industriq’s VP of AI and Head of Elisa DES, delivered one of the keynote speeches, underscoring the importance of intelligence in making such projects viable.

“We’re making energy history with Finnish engineering courage. When electrification is paired with heat production, storage, and intelligent optimization, we bring stability to the entire energy system,” Salmenkaita said.

While Polar Night Energy provided the hardware, Elisa Industriq brought the operational intelligence. Its AI-driven control system transforms the Sand Battery from a normal heat storage into an active energy market participant. The software continuously decides when to charge, discharge, and bid into Fingrid’s (a Finnish Transmission System Operator) reserve markets, ensuring the asset earns revenue while delivering reliable, profitable and sustainable heat. This is not simple automation; it’s real-time, multi-market optimization. Elisa Industriq’s algorithms forecast heat demand, electricity spot prices, and reserve market signals, then allocate capacity for the maximum impact.

”The Sand Battery can be adjusted quickly and precisely, and it also has a remarkably long energy buffer, which makes it ideal for reserve market optimization. Our AI solution automatically identifies the best moments to charge and discharge the Sand Battery and allocates flexibility capacity to the reserve products that need it most. Continuous optimization makes it a truly profitable investment,” said Jukka-Pekka Salmenkaita.

Elisa Industriq’s energy optimization solution balances three objectives simultaneously:
•    Meeting local heating needs
•    Minimizing electricity costs
•    Maximizing reserve market income

Salmenkaita explained why this matters:
“With advanced optimization, annual returns can exceed far above conventional strategies. That difference shortens payback time and makes projects like this scalable.”

The Sand Battery is more than a local innovation, it’s a system-level solution to one of the biggest challenges in the energy transition: flexibility. As Finland’s renewable capacity grows (8.36 GW of wind power by the end of 2024), the grid faces periods of surplus and scarcity. Long-duration storage like Sand Battery bridges those gaps, storing clean electricity as heat for days and releasing it during windless, freezing spells.

This flexibility is critical because heat and electricity demand peaks often coincide. By electrifying district heating and pairing it with storage, municipalities and district heating companies can reduce emissions, stabilize costs, and strengthen energy security. For Finland, where nearly half of homes rely on district heating, the impact is enormous.

Globally, the stakes are even higher. Industry consumes 37% of the world’s energy, and two-thirds of that is for heat—mostly produced by burning fossil fuels. High-temperature storage combined with AI optimization offers a scalable way to cut emissions in sectors like chemicals, pulp and paper, and food processing.

“This is not just a climate action. It’s about resilience and cost stability for communities and businesses,” Salmenkaita concluded.