Slovenian coal mine looks to gravity energy storage for greener future

An operational coal mine in Slovenia has become the latest mine in Europe to look to gravity energy storage in an effort to decarbonise.

The Velenje mine in the northeastern part of Slovenia is currently a fully operational lignite mine, with six working shafts and more than 1,600 mine employees.

The mine operators have now commissioned a feasibility study to examine how underground gravity energy storage – provided by Edinburgh firm Gravitricity – could offer a low carbon future as the mine winds down operations in the 2030s.

Gravitricity has developed a unique energy storage system, known as GraviStore, which raises and lowers heavy weights in underground shafts – to offer some of the best characteristics of lithium-ion batteries and pumped hydro storage.

The mine’s parent company HSE Group is already Slovenia’s largest producer of renewable electricity, and any future storage scheme could potentially be combined with on-site solar generation to support the country’s transition to net zero.

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Gravitricity engineers have already visited the site to assess the technical feasibility of installing systems in two specific shafts one of which is a ventilation shaft which may become available for a potential pilot project, which could start as early as next year.

Gravitricity engineering project manager, Nigel Voaden said: “The Velenje mine could be very well suited to future energy storage schemes as the operational shafts are both deep and in excellent condition and we are grateful to the mine’s operators for commissioning this study. Any future project could offer a new future to many of the hundreds of people who work at the mine today.”

“The survey includes an all-site assessment looking at energy demand, production, and storage, provides an initial calculation of the potential energy storage capacity for each of the six shafts on site, and completes a technical feasibility assessment for the installation of two GraviStore systems,” Voaden says.

Following submission of Gravitricity’s findings, the Velenje mine operators will have the opportunity to consider a second phase of the feasibility study prior to any final decision on a pilot scheme.

Gravitricity is currently fundraising on the Crowdcube platform and has already passed its £500,000 ($632,000) funding target.

Learn more about how mines are shifting to incorporate greener projects in this episode of the Energy Transitions Podcast with Margus Vals, member of the Enefit management board