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A battery made of SAND?

4 April, 2024

A battery made of sand

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You may think that batteries need to use metal only. Well, the Finns are here to prove us all wrong! They created a battery made of sand and they can use it to heat up to 5000 people.

A battery made of sand? But how?

Let’s first start with who, shall we?

Polar Night Energy are a startup based in Finland. They recently secured the sum of 7.6 million Euros in seed funding, that will help them in their efforts to make energy production carbon-free and establish themselves as the global leader of large-scale thermal energy storage solutions. And all this came from their idea to build a battery that will store heat and distribute it as needed. Although there is nothing new to the idea of storage heaters, the genious behind their battery is the material they chose to store the heat. It is something in abundance, with zero environmental impact, doesn’t need mining, doesn’t need complicated equipment to produce and is extremely efficient and resilient. It’s called sand. Yes, the one you find at deserts and beaches. Just sand.

What problem does sand solve?

To provide the answer, we need to see the whole process of energy production first.

Using any source of renewable energy, such as the sun or wind, we can produce energy that is ready to either store, or use immediately. When our energy needs are covered, the excess energy needs to be stored somehow, so that it can be used at a later stage, when the renewable energy source cannot produce more. Nothing new so far.

The problem is how long we can store that energy for. For example, solar batteries have a natural rate of discharge, and even though the storage period can be long, it can’t be too long. But what if we could convert the electric energy we produce through reneables to some other form that would allow us longer term storage? And what would that form be?

The answer is sand!

That was the revelation. Tommi Eronen (the CEO of Polar Night Energy) and his team, discovered that if they use the renewable electricity they acquire to power a heater. The heater warms up air that runs through pipes, which is then send to a big tank full of sand., they could retain the heat for very long periods. We are talking about several weeks or even months! And its efficiency in retaining heat is close to 95%, something that very few other means of heat storage can achieve.

But isn’t sand becoming scarse?

Yes, it is. This is one of the modern ecological issues. That’s why Polar Night Energy don’t use sand that is used in construction or sand from the beach, but prefer sand of any thickness that others consider waste. Not only that, but the waste coming from other mining operations is ideal for their sand batteries. So, if anything, they are actually contributing in improving waste management from mining. Not only that, but their batteries can actually use any sort of crushed aggregate that has similar properties to sand, like for example soapstone, which looks like sand and is a byproduct of several manufacturing processes, easy to find, and other companies consider it waste.

Is it scalable?

It is, and if you consider the amount of sand-like waste that is just lying there waiting to be used, you can imagine the extent of applications where this can be used. We hope to see the technology expand worldwide and be adopted in more countries around the globe, especially where heating is a matter of life and death. And the Finns know from low temperatures…