Innovative ‘sand battery’ is green energy’s beacon of hope

September 7, 2022
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When you think of batteries, you probably think of lithium. If you’re old enough to remember when one started corroding inside your CD player or GameBoy, the idea of using batteries might bring back some sad childhood memories.

Lithium batteries don’t hold much energy and are terrible for the environment when not recycled properly. After ending up in landfills or rivers, chemicals inside leak into soil and contaminate groundwater and surface water, harming surrounding ecosystems.

True, sodium-ion batteries are cheaper and more sustainable, as the Earth’s crust hosts 1000x more sodium than lithium, regardless of where you are in the world. But engineers are constantly looking for more sustainable options, especially when it comes to storing clean energy from wind, solar, and hydro.

In a major breakthrough, a pair of young Finnish engineers have figured out how to store green-generated power inside of a ‘sand battery’. Tommi Eronen and Markku Ylönen are the young founders of Polar Night Energy and have just rigged the world’s first sand battery to a commercial power station in Finland.

How does the sand battery work?

Russia’s invasion of Ukraine caused Finland to be cut off from its gas and electricity supplies. And since wind and solar power depend on weather, they tend to only work intermittently – posing an unreliable source of energy for entire communities.

This has long been a weak spot for renewables, but as Eronen and Ylönen have discovered, grains of sand are surprisingly good at storing clean energy.

After piling 100 tons of sand into a 4×7 metre steel container, the sand is heated by wind and solar power. This heat can be stored and redirected by a local energy companies, providing warmth to buildings in nearby local towns.

This happens through a process called resistive heating, where the sand is heated by the friction of electrical currents. The warmth occurs when electricity passes through any material (like sand) that isn’t a super conductor (materials that have no electrical resistance).

It sounds simple enough, right? Eronen and Ylönen’s sand battery is already working to heat homes, businesses, and the local swimming pool in the Kankaanpää district of Finland.

Speaking of their sand battery, Ylönen agreed – it’s simple. ‘There’s really nothing fancy here. The complex part happens on the computer; we need to know how the energy, or heat, moves inside the storage, so that we know all the time how much is available and at what rate we can discharge and charge.’

How sustainable is sand?

The next question that needs answering is, can this battery be implemented around the world? And will extracting vast amounts of sand harm the natural environment?

Although sand can be found all over the world, it is a material in high demand, especially for its use in construction projects. According to one study, the demand for sand is set to grow by 45 percent in the next four decades.

Sand used for building is typically removed from rivers and lakes, which can be detrimental to the environment. But Eronen and Ylönen say that, for sand batteries, where it’s sourced from doesn’t particularly matter – any sand with a high enough density would work to store heat for clean energy.

So with this simple, but genius design, the future of storing clean energy just got a lot brighter. Interest in the Polar Night Energy project has already been piqued all over the world, with many countries looking for ways to store their clean energy before winter hits.

As countries try to move away from fossil fuels, it’s great to see another practical green storage solution put forward – especially when it has potential to work virtually anywhere in the world.

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