Finland’s radical answer to a renewable energy headache

A small town in southern Finland has turned to the world’s largest commercial sand battery to solve what many see as the most critical problem facing renewable energy: intermittency.

The eye-catching facility, which is 13 meters high and 15 meters wide, provides 100 megawatt hours of thermal energy by storing clean energy in the form of heat using 2,000 metric tons of crushed soapstone.

This is enough to provide the 5,000 inhabitants of Pornainen with about a month’s heat demand during the summer and about a week’s heat demand in the winter.

Giant sand battery built by Finnish district heating company Loviisan Lämpö and developed by Polar Night Energy started last year as part of an effort to introduce flexible heat generation technology and reduce carbon emissions produced by the local district heating network.

Polar Night Energy said the project has reduced greenhouse gas emissions from the heating network by almost 70% and is estimated to reduce sawdust use by around 60%. An existing wood chip power plant continues to operate as a backup and peak load facility.

Tommi Eronen, CEO of Polar Night Energy, said Pornainen previously relied on burning oil and woodchips for its heating needs, but the town’s sand battery can now provide burn-free heating for much of the year.

“We are transitioning from a world where large power plants produce energy to a world where solar and wind produce energy, and then we need huge amounts of storage,” Eronen told CNBC in a video call.

“Hopefully a large portion of these storages could be sand battery type storages where we don’t need rare earth materials like we do in many chemical batteries like lithium ion batteries.”

The Pornainen project is approximately 10 times larger than the previous version launched in the country in 2022, strengthening the potential for sand batteries to play a more prominent role in reducing emissions both at home and abroad.

Battery storage is expected to play a crucial role in the energy transition, and sand batteries in particular show promise for district heat storage, but scaling up this technology faces significant hurdles. Some notable criticisms include their ability to efficiently recycle heat into electricity and their relatively low energy density compared to traditional batteries.

Essentially, sand battery technology works like a giant thermos with heat-storing material.

The first step is to extract electricity from the grid when there is abundant wind or solar power, then heat the sand to very high temperatures. The heavily insulated silo traps this heat for days or weeks before being discharged through heat exchangers into hot water for the local district heating network.

“Three steps – and the key to the whole thing is that the sand ensures that there is a delay between when you use electricity and when you use steam,” Polar Night Energy’s Chief Commercial Officer Annette Höglund-Dönnes told CNBC via video call.

“This delay is your business advantage because you can heat sand when electricity is cheap and you use steam at a time when it would normally be very expensive to produce steam from the grid, which is during the day when everyone is using it,” he added.

Höglund-Dönnes compared the process to charging a mobile phone overnight, given that it may be cheaper than during the day.

When asked whether the project could be replicated internationally, Höglund-Dönnes said Polar Night Energy had been contacted by teams from “every continent”, particularly communities dependent on fossil fuels such as coal and oil.

climate scientists It has repeatedly warned that a significant reduction in fossil fuel use will be required to prevent global warming; chief driver from the climate crisis.

Jan Rosenow, professor of energy and climate policy at the University of Oxford in the United Kingdom, agreed that electrothermal storage technologies such as sand batteries could be replicated worldwide.

“You don’t need rare earths, critical raw materials, and the nice thing is when electricity is cheap you can charge the battery and discharge it when you need heat,” Rosenow told CNBC.

“And you can store it for extended periods of time, not just two hours or four hours like lithium-ion batteries, but potentially days or even weeks.”

For example, criticisms of renewable energy are often Pointing out that technologies such as solar and wind only produce energy when the wind blows or the sun shines, Dr.