One of Europe’s deepest mines is being transformed into an underground energy store. It will use gravity to retain excess power for when it is needed. The remote Finnish community of Pyhäjärvi is 450 kilometres north of Helsinki. Its more than 1,400-metre-deep zinc and copper Pyhäsalmi mine was decommissioned but is now being given a new lease of life by Scotland-based company Gravitricity.
The firm has developed an energy storage system that raises and lowers weights, offering what it says are “some of the best characteristics of lithium-ion batteries and pumped hydro storage”.
When there is excess power – from wind turbines on a windy day for example – weights would be winched up the Pyhäsalmi mine’s 530-metre auxiliary shaft. To generate energy these weights can be released. This turns the winches into generators, creating either a short burst of electricity or a slower trickle depending on what is needed.
The gravity energy system would be able to store 2MW of power and integrate into the local energy grid.
A study published by a team of international researchers last month found that gravity batteries in decommissioned mines could offer a cost-effective, long-term solution for storing energy as the world transitions to renewable power.
Scientists from the International Institute for Applied Systems Analysis (IIASA) found that the world’s abandoned mine shafts could store up to 70TWh of power – roughly the equivalent of global daily electricity consumption.
