Thinker's Chronicle

Sand Battery: From A Pile of Sand to Energy

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By: Sakshi Agashe

The Beginnings of the Idea

A Finnish company called Polar Night Energy has designed the first commercial-use sand battery that can use low grade sand to effectively heat homes in the winter. The idea of two Finnish engineers, Tommy Eronen and Markku Ylӧnen, came into reality in late July when the battery was officially launched. While implementing the sand battery, the engineers pleasantly discovered that the battery had greater potential than originally calculated. Currently, it is installed at the Vaajakoski power plant, where it helps heat the district. Standing 23 feet tall, this intimidating steel stilo could also aid Finland to become less dependent on Russian gas supplies, which have been cut off before by Russia during the Ukraine War.  

Why Need a Sand Battery?

With the rising cost of oil and petrol, Finland’s sand battery could be key to battling its cold winters and high demand for heating. A four-by-seven meter battery filled with 100 tons of sand could be an innovative solution to the problem of renewable energy storage. While solar and wind energy produce high amounts of energy, the main issue arises in storing the energy for later use when there is demand for it. This effective yet cheap battery has the ability to transform and store the renewable energy into large amounts of heat, available even for months after heating in the winter.

Photo Credit: Energy Digital

The sand is a good alternative to the typical lithium batteries which are expensive, unable to store large amounts of extra energy, and contain toxic metals which may contaminate water supplies. The sand battery instead allows a cheaper and environmentally safer solution. Even though the sand battery can only store heat and not electricity, it can still be very useful in many industries.  

How Does it Work?

Solar panels or wind turbines generate the electricity, some of which is sent directly to houses, while the rest is used to power a resistance heater in the sand battery. The heater produces heat through friction similar to a toaster, heating up the sand to 500ºC (932ºF).  The sand battery has eight megawatt-hours of energy storage and 100 kilowatts of heating power. For perspective, one megawatt-hour can run an average American home for 1.2 months, meaning it will take longer to expand it to a larger scale to power a large city. According to Polar Night Energy, the battery can stay heated for three months or more, which is beneficial when there is low solar energy during the winters.

Photo Credit: BBC