Sweden-based sustainable power transition enabler Mine Storage cofounder and CEO Thomas Johansson notes that the company’s concept of using abandoned underground mines – or those under care and maintenance – as energy-storage facilities has progressed to the prefeasibility phase.

He explains that Mine Storage, as part of a consortium, secured funding from Sweden’s Energy Agency, in December, to create a blueprint for what will become a pilot. The first underground mine storage facility will be constructed in Sweden.

The mine, where the blueprint is being formulated, is located in the historical mining area of Bergslagen, and will include a step-by-step outline of the processes involved – from attaining initial landowner and authority approval to constructing grid-connected, energy storage.

The consortium comprises mining companies Boliden and Lovisagruvan, energy company Mälarenergi, hydropower equipment manufacturer Voith Hydro and engineering and design company AFRY.

Johansson tells Mining Weekly that the work is being conducted under the banner of the Strategic Innovation Program Swedish Mining Innovation, a collaboration between Innovation Agency, Formas and the Swedish Energy Agency.

“The concept is beautiful in its simplicity, whereby we use the cleanest medium there is, water, and the most reliable force, gravity,” he enthuses.

Energy is stored by pumping water from the bottom of the mine to a higher elevation using pumps powered by electrical energy from the grid and thus increasing the potential energy of the water.

The energy is stored by keeping the water in the upper reservoir and can later be released by having the water flow down to drive turbines and generators so that electricity is transmitted back into the grid.

The main requirement for an underground mine energy storage solution is two reservoirs with a minimum difference of 50 m in elevation, which is easily achievable in almost any underground mine.

“Mine Storage aims to use well-proven, state-of-the-art hydropower and pumping equipment developed over the past century,” says Johansson, adding that the “innovation” is the application of the technology in a mine setting.

Amid the rapid emergence of inconsistent renewable power production, such as wind and solar, the need for energy storage is growing exponentially.

Environmental Aspects

Johansson suggests that, in principle, mine storage is a closed-loop system, which does not actually use or deplete water. This bodes well for countries subjected to water scarcity or restrictions.

“Naturally, sourcing the initial water needed and assessing how evaporation will be managed during operation are part of our considerations and assessments during early project qualification,” he stresses.

Further, Mine Storage is fully committed to sustainable goals and, therefore, every mine site must meet its unique qualification process and defined conversion measures.

Johansson says the extent of a mine’s rehabilitation, prior to implementing mine storage, is connected to the environmental, hydrological, hydraulic and rock-mechanical aspects, all of which need to be thoroughly assessed before installation.

“Although many of the assessments will be undertaken from a desktop, some will also require on-site testing and analysis.”

He adds that the company will use its expertise for its Mine Storage Way of Working(WoW), which is the company’s collective intellectual property and know-how, to ensure quality and efficiency in all its future processes.

Although the concept is still in its infancy, the company has engaged with its international contacts and has identified possible project opportunities.

“The key for us – and integral to our Mine Storage WoW strategy – will be the ability to secure a business case for every new project, which, in turn, will entail a market and revenue assessment, as well as an analysis on the suitability of the site and the expected capital expenditure.”

Mine Storage aims to be a global leader in mine-based energy storage, with part of its WoW strategy being to find partners that will enable rapid upscaling on an international front, Johansson concludes.