Sand Batteries



Renewable energies – mainly solar and wind – are the future. They undoubtedly make sense, too. Not only will they arrive on an unlimited time scale, but they are safe to harness and free, beyond the initial infrastructure and sporadic upkeep. With current technology and usage, a solar panel the size of Nevada could power the entire planet.

The current problem (we have power puns around here for daze) with renewables is a matter of storage. Our battery capacities do not yet allow us to hold charges long enough to solve the demand for electricity. If one needs power when the sun shines, solar cells are fantastic. When night arrives or when an area receives less light – winter or rainy seasons – our batteries cannot keep pace.

Many of the energy repositories we employ today rely on lithium. They are expensive and require a big engineering footprint. Though incremental improvements to these batteries continue, some scientists in the field believe we are close to maxing the technology. That potentiality would be a large problem for renewable energy.

A Finnish company believes they have a partial solution: sand!

A satellite image of the world's largest solar array, which currently covers 14,000 acres in India

The batteries we’re used to using involve chemical reactions. How in the world can sand create a battery?

It’s all about heat. No chemical reactions are necessary!

The idea is stunning in its simplicity. Generate electricity via solar or wind. Use some of the electricity normally. Convert the rest to heat through resistance. This step is extraordinarily easy. Think about all the heat an engine produces. In most circumstances, this heat is inefficient and wasted. In the case of a sand battery, turning electricity into heat is exactly what you want, so it’s 100% efficient. Transfer the heat to a giant heap of sand. In an insulated environment, sand can warm up to 500 degrees Celsius. Pipe water through the sand battery, which warms the water. This heated water can be transferred to homes or other buildings to provide heat for the edifice!

The best part about this battery is the sand can remain hot for months or even years. Like the London Underground, which has essentially become a clay oven, the natural properties of sand allow it to be a superstar when it comes to retaining heat. This storage ability solves a big part of the problem with renewables: using the energy exactly when it’s needed.

This idea is not theoretical, either. A company called Polar Night Energy has already installed a sand battery in a town named Kankaanpää. That the impetus for this notion arrives in Finland makes much sense. Long, cold winters with little sunlight mean using renewables there will require a storage resolution. If Finland can scale sand batteries, they can more quickly gain energy independence from Russia, as well.

Sand batteries are, of course, not a magic bullet. The sand does not store electrical charge like a normal battery, so the system can only provide heat. However, raising the temperature of living and working areas during winters is a significant chunk of a grid’s work. If sand batteries can take that concern away from a macro system, the overall solution becomes a much easier task.

The best part is the raw material can be extraordinarily low-grade sand. So, not only is the battery simple mechanically, but it’s also very cheap!

The first Finnish sand battery

Other nations have started to investigate the potential for sand batteries in the quest to transition to renewable energy. The US National Renewable Energy Laboratory developed a more complex version of the sand battery that it hopes can provide a piece to the larger puzzle.

Where we once hoped to revolutionize chemical batteries, many scientists have started to turn to low-tech ideas. Soon, you might have sand to thank for your district’s  heat!

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