First commercial gravity storage for energy planned in Finnish mine

Gravitricity, a Scottish company, has set its sites on turning a closed Finnish mine into a giant storage battery for renewable energy. The GraviStore gravity energy storage system (GESS) is the first commercial-scale deployment of such technology in an underground mine.

The GraviStore system raises and lowers heavy weights in shafts. When a renewable system produces surplus power, the surplus is used to raise the weight. And when more power is needed than can be generated, the weight is lowered – thanks to gravity – to produce additional power which is fed into the distribution system.

Power can be released either in a large burst or more slowly as the weight lowers. A 530-metre-deep auxiliary shaft has been selected for the location of the GESS. It will provide up to 2 MW of storage capacity.

Gravitricity has chosen the former Pyhäjärvi mine, Europe’s deepest copper-zinc mine. The mine was opened in 1962 by Outokumpu, sold to Inmet Mining in 2022, and acquired by First Quantum Minerals (TSX: FM) in 2013. The mine was shuttered in 2022, but the refinery will remain active until 2025.

The nearby community of Pyhäjärvi, 450 km north of Helsinki, has 5,000 residents. Energy storage has the potential to provide new low-carbon jobs to replace those lost when mining ceased. And this is not the only location where the strategy can be employed – think of closed coal mines as society evolves its low-carbon lifestyle. Ideally, the GESS system would be built into any mine during decommissioning.