Finland tests a sand battery to store clean energy

Photo: Ivan · Pexels

One of the biggest problems with renewable energy isn't generating clean electricity, but storing it for when it's actually needed. The sun doesn't always shine and the wind doesn't always blow when demand peaks, and that's where a simple yet unconventional idea comes in: using sand as a large-scale thermal storage system. Finland has launched what is described as the world's largest sand battery.

The principle behind the technology is simple. Surplus electricity, generated during periods of low demand or high renewable output, is used to heat sand to very high temperatures. That sand retains heat for long periods and can later release it for heating or industrial processes, effectively working as a giant thermal battery that doesn't depend on the critical materials required by conventional chemical batteries.

A response to a structural problem

Interest in this kind of solution stems from a structural problem in the energy system: as the share of renewables in the grid grows, so does the need for cheap, scalable storage that doesn't rely solely on lithium or other minerals with limited supply. Sand, abundant and cheap, offers an alternative that could complement electric batteries in specific uses, especially in cold climates where heating accounts for a huge share of energy consumption.

It's still early to know whether this technology will spread beyond pilot projects like Finland's, but the experiment shows just how far the energy transition is pushing the search for solutions outside the usual paths.