A very Finnish thing’: Big sand battery to store wind and solar energy using crushed soapstone
The battery will be able to store a week’s heat demand in winter - how does it work?
A huge sand battery is set to slash the carbon emissions of a Finnish town.
The industrial-scale storage unit in Pornainen, southern Finland, will be the world’s biggest sand battery when it comes online within a year.
Capable of storing 100 MWh of thermal energy from solar and wind sources, it will enable residents to eliminate oil from their district heating network, helping to cut emissions by nearly 70 percent.
"It's exciting to build a large-scale thermal energy storage, which will also act as a primary production plant in Pornainen's district heating network,” says Liisa Naskali, COO at Polar Night Energy, the company behind the innovation.
“This is a significant step in scaling up the sand battery technology.”
How will the sand battery serve residents in Pornainen?
Having refined its charging algorithms, Polar Night Energy is now ready to scale up the storage tech in Pornainen. Once completed, the new battery will be integrated with the network of Loviisan Lämpö, the Finnish heating company that supplies district heating in the area. "Loviisan Lämpö is moving towards more environmentally friendly energy production. With the Sand Battery, we can significantly reduce energy produced by combustion and completely eliminate the use of oil," says CEO Mikko Paajanen. The project also aligns with Pornainen’s plans for carbon neutrality. Many of its buildings, including the comprehensive school, town hall, and library, rely on district heating. Mayor of Pornainen Antti Kuusela says the municipality “welcomes all innovative development projects that reduce emissions in district heating operations and contribute to network expansion.” In total, the sand battery is expected to knock off 160 tonnes of carbon dioxide equivalent emissions per year. As well as weaning the town off oil, woodchip burning is expected to drop by 60 per cent as a result. The battery’s thermal energy storage capacity equates to almost one month’s heat demand in summer and a one-week demand in winter in Pornainen, Polar Night Energy says. Construction and testing of the 13 metres high by 15 metres wide battery is estimated to take around 13 months, meaning it should be keeping residents warm well before winter 2025.Is sand a sustainable material?
“We wanted to find something that can be sourced nearly everywhere in the world,” Markku said. But is sand as ubiquitous as we might think? Demand for the construction material is set to soar by 45 per cent in the next 40 years, according to a recent Dutch study. Building sand is typically extracted from rivers and lakes, and ‘sand pirates’ are speeding up its loss from these ecosystems. But as far as the Finnish engineers are concerned, it doesn’t really matter where the sand comes from. Though builders’ sand was used initially (to limit transport emissions), sand batteries work with any sand-like material that has a high enough density, within certain thermodynamic parameters. In Pornainen, Polar Night Energy has found a sustainable material in crushed soapstone; a by-product of a Finnish company’s manufacture of heat-retaining fireplaces. "Tulikivi is a well-known and traditional company,” says Naskali. “The soapstone they use is a very Finnish thing.” "We always choose the thermal energy storage medium based on the customer's needs. Examining and testing different materials is crucial for us to use materials that are suitable in terms of properties, cost-effectiveness, and promotion of circular economy," she adds. Polar Night Energy has big ambitions to take its technology worldwide. As Markku told us back in 2022, “we want to build a hundred times larger storages around the world as fast as possible.”Source euronews.green