Could sand be an alternative to lithium when it comes to green energy storage?

PARIS: Is sand the material that could one day replace lithium in batteries for renewable energy technologies? Such is the idea of a team of Finnish engineers who have developed a new kind of battery.

The Finnish company Polar Night Energy, located in Kankaanpää in the west of the country, has developed a battery based principally on sand.

This new type of battery is actually a large steel tank installed in a power plant and filled with construction sand. It could potentially save 169.8 megatons of CO2e per year by 2030 (or between 56.6 megatons and 283.1 megatons of CO2e per year), according to Mission Innovation, a global clean energy initiative.

Strictly speaking, this battery will not be able to produce electricity, since it will only be used to store heat produced from surplus solar and wind energy during the summer. This heat can then be discharged and used to heat homes, business premises or municipal buildings, starting from next winter.

The sand stores heat at about 500°C, making it possible to heat houses in winter when energy is more expensive. This offers a means of limiting energy costs — ecologically, politically and economically — especially since one third of energy consumed in Finland comes from Russia.

Before May 14, 2022 (when Russia halted energy deliveries to the Nordic country), around 10% of Finland's electricity supply came from Russia.

The device developed by Polar Night Energy also has the advantage of offering an alternative to lithium, a rare metal used in the manufacture of photovoltaic panels and wind turbines (as well as smartphones and electric cars), the extraction of which raises major ecological and social concerns. Moreover, lithium is a rare metal, and the threat of a shortage looms in the coming years.

Seen from this angle, the use of sand to store energy seems opportune. But the quantity of sand used in the Polar Night Energy battery is not negligible, since more than 100 tonnes are poured into the tank used for this purpose.

Naturally created by the erosion of rocks near water sources (oceans, seas, rivers, etc.), sand is the second most exploited natural resource after water, according to a UN report published in April.

But, unlike water, few official regulations are in place to ensure a reasonable use of sand.

This is a real social and environmental problem, since this resource is subject to major trafficking and illegal extraction, generating conflicts and causing insecurity for the inhabitants in some countries, as is the case in India or Morocco.