UK firm to convert Europe's deepest mine into its first ever gravity battery

Once production hub of zinc and copper, the mine will now store renewable energy and supply it on demand to the grid.

UK-based energy storage firm Gravitricity will soon begin work to convert Europe's deepest mine into the first-ever gravity-based battery. The 4,737 feet (1,444 meters) deep mine is located in Pyhäjärvi, ~280 miles (450 km) north of the Finnish capital of Helsinki, according to Interesting Engineering. 

Owned by Canadian firm First Quantum Minerals, the deepest mine in Europe, it was a source of zinc and copper. It was the biggest employer in the region, providing 600 direct and indirect jobs. In August 2022, production from the mine ceased, following which the community began exploring multiple initiatives at the site. 

"We can take advantage of the best of the region's electricity grid and transformation of the energy market," Henrik Kiviniemi, CEO of local development company Callio Pyhäjärvi, told The Engineer. "It is also very attractive to take advantage of these opportunities for energy-intensive industry to be located here utilizing also the good logistical location of Pyhäjärvi."

Gravity-based battery

Edinburgh-based Gravitricity has developed Gravistore, a gravity-based system that can serve as a battery to store excess energy from renewable sources. On a sunny or windy day, when solar or wind farms produce more energy than the demand, Gravistore stores can raise weights placed in defunct mineshafts to store the energy. 

During higher demand, the weights can be lowered to release the energy, with shaft winches serving as power generators. Depending on the requirement, the weights can be released slowly in a short burst to cater to the energy demand. 

Gravitricity will now use a 1,700-foot (530 m) auxiliary shaft to build a 2MW prototype to demonstrate its technology, the first of its kind in Europe. According to its website, Gravitricity has also been working on identifying mines in other countries, such as the Czech Republic, Germany, and India.

Advantages of Gravity-based battery

Gravity-based energy storage systems have been attempted in various forms. They are considered feasible alternatives for lithium-ion battery storage systems. Interesting Engineering has previously reported how a gravity-based energy storage project in Switzerland took 14 years to build and can power 900,000 homes. 

In comparison, Gravitricity's solutions use existing infrastructure, such as deep mines, that can be repurposed once mining operations cease. Not only does this approach provide new employment opportunities in the remote regions where these mines are located, but it also provides lithium-ion battery-like storage characteristics. 

For instance, gravity-based batteries can go from zero to full power in less than a second. It is also modular, allowing designers to tweak its capacity based on local conditions and requirements. 

The technology fares better than lithium-ion batteries in efficiency and costs. Lithium-ion batteries often suffer from problems of standing losses of energy, but gravity-based batteries don't. The system is also much cheaper to deploy and operate and is not limited to a finite number of cycles or years to deliver energy storage. 

"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," added Martin Wright, executive chairman of Gravitricity.