One of the deepest mines in Europe will be transformed into a green energy store by using gravity to store excess power for when it is needed.

Edinburgh energy storage firm Gravitricity has inked a deal to install its gravity energy storage system in a 1,444-metre deep mine near the Finnish community of Pyhäjärvi, 450 kilometres north of Helsinki.

A 530-metre deep auxiliary shaft would be transformed into a 2MW capacity prototype of Gravitricity’s technology – its first use in Europe.

The zinc and copper mine is currently owned by Canada’s First Quantum Minerals.

Gravitricity uses its GraviStore system to raise and lower heavy weights in underground shafts to store and discharge energy.

When there is excess electricity, for example on a windy or sunny day, the weight is winched to the top of the shaft ready to generate power.

This weight can then be released when required – in less than a second – and the winches become generators, producing either a large burst of electricity quickly, or releasing it more slowly depending on what is needed.

Gravitricity's executive chair, Martin Wright Photo: Gravitricity

Gravitricity says this offers “some of the best characteristics of lithium-ion batteries and pumped hydro storage.”

The local community has set up a special development company, called Callio Pyhäjärvi, to promote regeneration projects at the historic mine.

The GraviStore system would “tie straight into the local electricity grid and provide balancing services to the Finnish network,” said Gravitricity.

Gravitricity’s executive chair Martin Wright, who also chairs the UK-based Renewable Energy Association, said the project will “demonstrate at full scale how our technology can offer reliable long life energy storage that can capture and store energy during periods of low demand and release it rapidly when required.”

“This full-scale project will provide a pathway to other commercial projects and allow our solution to be embedded into mine decommissioning activities, offering a potential future for mines approaching the end of their original service life.”

Gravitricity is advancing several GraviStore projects, including a plan to transform state-owned mine infrastructure in the Czech Republic into an energy store.

The company is also targeting old mines in the US as a site for its technology.

Another company that uses a similar system to store energy is Switzerland-based Energy Vault, which was last year preparing to commission a ‘first-of-its-kind’ 100MWh gravity energy storage system near Shanghai.

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