Finland's Sand Battery: A Breakthrough in Energy Storage

A Novel Energy Storage Solution: Finland's Sand Battery

Recently, Finland has inaugurated what is currently the world’s largest battery utilizing sand as its core storage medium.

The concept centers around sand, surprisingly.

How Sand Batteries Work

A sand battery represents a thermal energy storage system. It employs sand or crushed rock to retain heat. Electricity, generally sourced from renewable energy, is used to elevate the temperature of the sand.

This accumulated heat can subsequently be utilized for diverse applications, notably the warming of buildings.

Economic Advantages and Material Sourcing

The economic benefits are substantial, and the cost-effectiveness is remarkable, particularly considering the crushed soapstone currently contained within an insulated silo located in Pornainen.

The soapstone itself was previously considered waste material – discarded by a Finnish fireplace manufacturer.

Impact on Carbon Emissions

While perhaps not as visually striking as a large lithium-ion battery installation, the 2,000 metric tons of pulverized rock housed within the 49-foot-wide silo is projected to significantly reduce Pornainen’s carbon footprint.

This will assist the town in phasing out expensive oil currently used to support its district heating network.

District Heating and Storage Capacity

Similar to many towns in Scandinavia, Pornainen operates a centralized boiler system that provides heat for residences and buildings throughout the area.

Developed by the Finnish firm Polar Night Energy, the sand battery can store 1,000 megawatt-hours of heat for extended periods – potentially weeks.

This capacity is sufficient to provide a week’s worth of heating during the cold Finnish winters.

Heat loss during both storage and retrieval is minimal, ranging from 10% to 15%, and the outlet temperature can reach up to 400°C.

Reduced Reliance on Wood Chips

The town’s district heating system also utilizes burning wood chips, and the sand battery is expected to decrease this consumption by approximately 60%, as stated by Polar Night.

The heat from the battery could also be converted into electricity, although this process would result in some efficiency loss.

Growing Interest in Thermal Batteries

With the decreasing cost of renewables, interest in thermal battery technology has been increasing.

Beyond Polar Night Energy, several startups are actively developing thermal batteries.

• Sunamp, based in Scotland, is constructing a battery utilizing a material similar to that found on salt-and-vinegar potato chips.
• Electrified Thermal Solutions, a 2023 Startup Battlefield runner-up, has created a brick capable of generating heat approaching 2,000°C.
• Fourth Power is producing graphite blocks that store electricity as heat reaching 2,400°C.

Finland’s Energy Landscape

Pornainen’s battery is charged using electricity sourced from the grid, and its substantial storage capacity allows for power acquisition during periods of lowest cost.

Finland’s energy grid is predominantly powered by renewables (43%) and nuclear energy (26%), resulting in relatively clean electricity.

Furthermore, it boasts the lowest electricity prices in Europe, at just under €0.08 per kilowatt-hour – less than half the EU average.

Cost Considerations

Polar Night Energy has not revealed the total project cost, but the raw materials are inexpensive, and the structure itself is not overly complex.

A smaller prototype, constructed several years ago, was estimated to cost around $25 per kilowatt-hour of storage.

The new, larger version is likely even more affordable.

In comparison, lithium-ion batteries currently cost approximately $115 per kilowatt-hour.