Monday, 25 March 2024 10:45

Slovenian coal mine looks to gravity energy storage for green future

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An operational coal mine in Slovenia has become the latest mine in mainland Europe to look to underground energy storage.

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.

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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.

Velenje is the latest mine to look to gravity storage, following mine sites in Finland, Germany, and the Czech Republic.

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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.

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.

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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 funding target.

Gravitricity is raising £500,000 investment on Crowdcube. Capital At Risk.

About Gravitricity

Gravitricity uses heavy weights suspended in a deep shaft by cables attached to winches. When there is excess electricity, for example on a windy 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.

See short (30 second) ‘how it works’ animation here.

Unlike batteries, the Gravitricity system can operate for decades without any reduction in performance. Gravitricity has an expanding portfolio of intellectual property in underground energy storage including eight granted patents and a further two pending. The idea of using gravity to store energy is not new. Britain already relies on a number of pumped storage hydro schemes, such as Cruachan Power Station, where water is pumped uphill to be released when required.

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

About Velenje coal mine

Despite the national and global trends aiming to transition to a low-carbon or carbon-neutral society, Premogovnik Velenje (Velenje Coal Mine), an associated company of Holding Slovenske Elektrarne, is still an important and indispensable pillar of the Slovene energy industry. Together with Termoelektrarna Šoštanj (Šoštanj Thermal Power Plant), it has been striving for decades to ensure undisturbed and reliable power supply for one third of Slovenia.

We are immensely proud that the foundations of today's image of the Šaleška dolina Valley are based on mining, as the Velenje Coal Mine has been the main driving force of development of the entire region since 1875, and its impact is often seen beyond the valley, as well.

We have extracted over 259 million tonnes of coal from the depths of the Šaleška dolina Valley. From the initial 3,500 tonnes in 1887, the biggest breakthrough in production happened in the 1980s, when mechanised mining equipment was gradually introduced, which helped us achieve the milestone of over 5 million tonnes of extracted coal per year. Nowadays, our production, which is primarily dependent on the consumption by the Šoštanj Thermal Power Plant, is around 2-2.5 million tonnes of coal per year.

Our story is based principally on tradition and our know-how, technological equipment, and technologies that we developed. We participate in some key development and research projects, co-financed by the European funds, which support high-technology development. Every year, our innovations are among the recipients of the highest regional and national awards. For years, we have been spreading knowledge, experience, technology, and equipment abroad.

Energy is the means for achieving our goals. By innovative thinking and professional and efficient work, we can improve the competitive position of the entire Velenje Coal Mine Group

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