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Mine Storage is currently in the process of qualifying several mines in Finland
applications. Typical discharge durations range from six to 24 hours, aligning with the needs of intraday balancing and peak shifting. While individual projects are smaller than many conventional pumped storage schemes, scalability is achieved through aggregation. “Scalability comes from building a portfolio of projects,” Olrog adds
Revenue, bankability and system integration
As with many infrastructure technologies, the transition from concept to deployment is driven as much by commercial considerations as by engineering performance. For Mine Storage, Olrog identifies three primary challenges: permitting timelines, grid connection queues and investor understanding. “The technology itself is well proven,” he says. “The challenge is demonstrating that it can be applied in this new context with the same level of reliability and bankability.”
Revenue stacking is central to this process. Mine
Storage projects are designed to capture value from multiple streams, including energy trading, ancillary services and grid support. Among these, ancillary services such as frequency regulation and reserve capacity are seen as the most critical for financial viability. “This is fundamentally a megawatt-based business,”
Olrog explains. “Ancillary services and grid support are the main drivers. Energy arbitrage is part of the picture, but it’s not the primary focus.” This reflects broader trends in electricity markets,
where the value of flexibility is increasingly recognised. Policy frameworks are beginning to evolve accordingly, with mechanisms such as the UK’s cap-and-floor model providing revenue certainty for long-duration storage assets. “We are starting to see supportive policy frameworks
emerge,” Olrog says. “And we expect that to expand into other markets over time.” Within the wider energy storage ecosystem, mine- based pumped storage occupies a distinct niche. Batteries provide high-speed response for short- duration applications, typically up to a few hours, while other technologies are being developed for seasonal storage. Mine Storage’s systems are positioned in the intermediate range, delivering sustained output over multiple hours. One of the more innovative aspects of Mine
Storage’s approach is the potential for co-location with data centres. This concept leverages the thermal
12 | June 2026 |
www.waterpowermagazine.com
properties of mine water, which typically remains at low temperatures, to provide efficient cooling. “The water in the system is around 4 to 6 degrees Celsius,” Olrog explains. “By using heat exchangers, we can provide cooling without the need for conventional chillers.” This creates a dual-use system in which the same infrastructure supports both energy storage and thermal management. For data centre operators, this can translate into significant reductions in both capital and operating costs. At the same time, co-located storage provides firm power and reduces peak demand on the grid. The concept also addresses some of the practical challenges associated with data centre development, including land use, noise and visual impact. Underground facilities can offer inherent advantages in terms of security and environmental integration. While discussions with potential partners are still at an early stage, the level of interest suggests that such integrated solutions could become an important part of future infrastructure planning.
Scaling a new infrastructure class Mine Storage’s long-term strategy is centred on
developing a repeatable model that can be applied across multiple projects and geographies. Rather than focusing on individual large-scale installations, the company aims to build a portfolio of assets. “Success is multiple projects reaching final investment decision and a repeatable development model,” Olrog says, describing the transition from early- stage development to a scalable platform. The company’s business model reflects this
approach. Projects are developed in partnership with utilities, municipalities and infrastructure investors, with capital generated from each development recycled into the pipeline to fund further projects. The Norberg project represents a key milestone, supported by a €20m grant from the European Innovation Fund and progressing through permitting and engineering phases, with commissioning targeted for 2030.
Looking ahead, Olrog sees mine-based storage as
a way to expand the geographical reach of pumped storage hydro. “We’re turning legacy mines into critical grid infrastructure,” he says, highlighting the potential to open up new locations for deployment and create a distinct segment within the sector. Globally, the potential resource base is substantial.
Thousands of decommissioned mines exist across Europe, North America and other regions, many of which could, in principle, be adapted for energy storage. However, realising this potential will require alignment between engineering feasibility, regulatory frameworks and market conditions. For hydropower engineers, the concept represents
an extension of established principles into a new context. By adapting existing infrastructure to meet modern system requirements, mine-based pumped storage hydro offers a pathway to increase deployment without relying solely on conventional site development.
In doing so, it may play an increasingly important
role in addressing the growing demand for long- duration energy storage, particularly in regions where traditional pumped storage opportunities are limited.
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