The World’s Biggest Sand Battery Is Now Working in Finland!

A company in Finland called Polar Night Energy has turned on the world’s largest sand battery in the town of Pornainen.

What is a Sand Battery?

Imagine a giant thermos filled with about 2,000 tons of crushed soapstone (a type of rock)! The soapstone was basically trash — thrown away from a Finnish fireplace maker. Inside, the sand is heated up to hundreds of degrees using electricity from wind or solar power. The sand holds onto the heat for days, weeks, or even months!

How Big is the Sand Battery?

An image of a modern, steel and glass, four-story office building. — Image: Four-story commercial building Credit: espiegle, iStock

The tank is 43 feet tall (13 meters, or about as tall as a four-story building) and 49 feet wide (15 meters, about as wide as a tennis court). Believe it or not, it can store up to 100 megawatt-hours of heat, which is enough to heat the town of Pornainen for a month in the summer and a week in winter.

Why is the Sand Battery Important?

Cuts pollution: It’s expected to lower carbon emissions in the town’s heating system by nearly 70%.

Saves fuel: Pornainen won’t need to burn oil anymore and will use 60% less wood chips in its heating plant.

Supports clean energy: The sand batters stores energy for later use when solar and wind power are abundant and cheap.

It’s cheap: A few years ago, the company built a much smaller sand battery to test the idea. They said it cost about $25 to store one kilowatt-hour of energy. That’s pretty cheap—especially when you compare it to lithium-ion batteries. Those cost about $115 for the same amount of storage. The new, bigger sand battery is likely even cheaper.

How Does the Sand Battery Work?

Image: A diagram showing how the sand battery works. Image credit: Polar Night Energy

When electricity is available, it heats up the sand. Inside the tank, there’s a network of pipes carrying hot air that heats the sand up to around 600 °C (super hot!) Later, the stored heat is used to warm water or air which heats up buildings and homes. It’s also simple, reliable, and lasts a long time. Sand keeps heat well.

What’s Next?

The company is planning more projects in Finland and beyond, including a test model that could convert heat back into electricity.

Why it matters:

This sand battery is a smart and low-cost way to store renewable energy without using chemicals or complex machinery. It helps towns use more clean energy and make their heating systems better for the planet.

Keep up on the latest solutions here: https://eco-nana.com/category/solutions/. Thanks for reading and caring!