Our thinking

Simply out-sanding

9 December, 2022

Finnish renewable energy company, Polar Night Energy Oy is on a mission to scale up a fascinating technology that stores electricity generated from wind and solar power as heat in sand. The technology is based on the simple concept of converting (clean) energy into heat, which is stored in silos of sand, known as “sand batteries”. The silos, equipped with sand and a heat transfer system can be kept outside buildings, or even underground – saving space and improving aesthetics.

As renewable energy generation capacity grows, we need clean and efficient energy storage to address the problem of year-round supply, a challenge for renewable energy. Renewable energy is great, but solar and wind power is unpredictable and supply varies during the day and the year. Lithium-ion batteries are the current go-to, but they have drawbacks including cost, large physical footprints, the impacts of lithium production and limited ability to store excess power. Sand batteries are a potential alternative that could be ground-breaking.

The sand battery technology is in its early stages, making the most out of a cheap, non-toxic and abundant resource that can be heated and kept at one-thousand degrees Celsius. The storing cycle ranges from hours to months, which means the sand can stay warm and the heat ready to use even when it’s not sunny or windy and, in the winter, when energy is at a premium.

Its potential to reduce demand on foreign energy supplies is important too. Sand batteries are a promising technology that can help increase self-sufficiency and mobilise the green energy transition.

The team at Polar Night Energy is working to expand their current technology and license it for wider use. Refining surplus electricity into valuable heat seems a clever move and whilst it is too early to say sand batteries are the definitive solution, we’ll be keeping our eye on the advances Polar Night Energy are making in the renewable energy world.

By Bertie Bateman