Wafricnews - June 2025

In a game-changing leap for global clean energy efforts, Finland has just switched on the largest sand battery ever built — a quiet but powerful breakthrough that could revolutionize how the world stores renewable energy.

The new battery, developed by Finnish startup Polar Night Energy, has the capacity to store up to 1,000 megawatt-hours of heat, which can be retained for weeks with minimal losses — and more importantly, it could be the key to cutting out fossil fuels from municipal heating systems entirely.

Storing Tomorrow’s Power in Yesterday’s Sand

Unlike the flashy solar panels or towering wind turbines that symbolize the renewable energy push, this innovation is deceptively simple: just sand and heat. But don’t be fooled — the technology powering this is anything but basic.

At the heart of the system is a 2,000-metric-ton sand-filled silo, where excess energy from solar or wind is converted into heat and stored inside the grains. The sand is heated to 400–500°C by running electricity through it. Because sand isn’t a good conductor, it resists the current and creates heat — which is then trapped and stored inside the silo.

When energy is needed, especially during colder months, that stored heat is pumped out as hot air and distributed to nearby homes, offices, and even a swimming pool. The process is cheap, effective, and crucially, doesn't require lithium or other rare earth materials.

One of the inventors, Markku Ylönen, explained it best: “There’s really nothing fancy there. The real challenge is in the computer modeling — understanding how the heat moves through the system so we can control when and how much to release or store.”

A Low-Cost, High-Impact Solution

One of the biggest draws of this sand battery is its economical and environmental friendliness. The sand used was essentially industrial waste — discarded by a fireplace company. The construction materials are low-cost, durable, and widely available. Unlike lithium-ion batteries that come with high costs and serious environmental concerns, this solution relies on local, non-toxic resources and has minimal carbon footprint during production.

So far, the battery has helped a small Finnish town ditch expensive and polluting oil-based heating systems, offering a proof-of-concept that has now drawn global attention.

Childhood Friends Behind the Revolution

The brains behind this innovation are not just engineers — they're long-time friends with a shared dream. Tommi Eronen, Markku Ylönen, Liisa Naskali, and Ville Kivioja grew up together in southern Finland, first connecting through athletics and later uniting over a shared concern for the planet.

From cheering each other on at track meets to tackling climate change as a team, their journey is a testament to how local inspiration can spark global solutions.

The Bigger Picture

As countries across Africa and around the world face rising energy demands and extreme weather challenges, affordable energy storage could be the missing puzzle piece. Solar and wind energy are now cheaper than ever — but storing the power they produce remains a massive hurdle.

Finland’s sand battery offers a glimpse of what’s possible when innovation meets urgency.

From a quiet town in northern Europe, a humble silo of sand might just heat up the future of global clean energy — and Africa, with its vast solar potential and need for scalable, low-cost storage, should be paying close attention.