Abandoned Mines to Grid Storage: The Kidson Pumped Storage Project and the Global Underground Energy Revolution

The video explains pumped hydro storage as a mechanical battery that uses gravity and water to store energy. It highlights the Kidson Pump Storage Project in North Queensland, which repurposes two old mine pits into upper and lower reservoirs connected by tunnels and a cavern, marking a world first in using two former pits for pumped storage. The discussion also covers the broader history, economics, and engineering hurdles of this approach, including environmental considerations and regulatory timelines.

• Two-reservoir pumped hydro stores energy by pumping water uphill when prices are low and generating electricity by releasing it when demand rises.
• Abandoned mines offer ready-made elevation differences and existing infrastructure to reduce cost and development time.
• Kidson is behind schedule but aims to start generating power, while researchers at Oak Ridge model safety and water behavior in repurposed mines.
• Globally, former open pit mines in Europe and deep Nordic shafts are being studied for underground energy storage, with multi-megawatt, multi-hour systems in consideration.

Overview and Context

Pumped hydro storage stands out as a highly efficient, long-duration energy storage solution that complements intermittent renewable energy sources like solar and wind. The video centers on the Kidson Pump Storage Project in North Queensland, Australia, a pioneering effort to convert a disused gold mine into a large scale energy storage facility. The project repurposes two old open pit mines into upper and lower water reservoirs, linked by underground tunnels and a powerhouse cavern carved into the rock. This approach aims to provide around 250 megawatts of installed capacity and up to eight hours of electricity generation, offering a dynamic alternative to conventional battery storage.

How Pumped Hydro Works

Traditional pumped hydro uses gravity to store energy. When grid demand is light or when cheap power is available, electricity is used to pump water from a lower reservoir to a higher one. Later, water is released to drive turbines and generate electricity. The system relies on elevation differences to create pressure and drive electricity generation, and it has operated since the 1890s as a primary form of grid scale storage.

Abandoned Mines as Storage Sites

The concept reframes the challenge of geography by using existing holes and shafts. Abandoned mines naturally provide elevation differences and pre-existing tunnels, which can lower the costs and timelines for development. However, old mines were not designed to hold large volumes of water under pressure, so engineers must address structural stability and water quality concerns, including potential acid mine drainage and mineral leaching. Oak Ridge National Laboratory is developing hydrodynamic and chemical models to simulate water behavior and ensure long term integrity before construction begins.

Kidson Pump Storage Project: Details and Timeline

Genex Power is turning two former open pit mines into upper and lower reservoirs connected by underground tunnels, with a cavern housing the turbines and generators. The project is notable as the first to employ two former mine pits in this way and Australia’s first new pumped hydro facility in about four decades. Commissioning has been delayed from the original 2024 target to 2026 or later. The core appeal is leveraging a hole left by mining to create a powerful energy infrastructure, balancing cost, time, and environmental considerations.

Engineering Challenges and Research

The main technical hurdles include structural stability under cyclic water pressures, water quality, and chemical interactions between stored water and old mineral seams. Oak Ridge National Laboratory is providing modeling tools to assess these risks for abandoned coal mine sites, focusing on stability, water chemistry, and grid connections to enable safer, faster decision making in project development.

Economic Considerations and Grid Role

Pumped hydro offers 70 to 80 percent roundtrip efficiency, which is lower than lithium ion batteries in peak efficiency but superior for long duration storage that batteries cannot economically provide due to safety and cycle life limits. While multi-megawatt scale, multi-hour storage projects involve substantial upfront costs, their long lifespans (50 to 80 years with proper maintenance) can yield favorable lifetime costs compared with evolving battery technologies. Batteries excel at short duration, high-frequency storage; pumped hydro and batteries thus serve complementary roles in a hybrid energy strategy.

Global Landscape and Future Prospects

Beyond Kidson, Europe is actively evaluating open pit lignite mines for pumped storage, identifying around 50 suitable sites among more than 100 analyzed pits. Nordic initiatives like Sustainable Energy Solutions Sweden are studying underground energy storage in Finland’s deep mines, using shafts to create segmented upper and lower chambers. In the US, Oak Ridge is extending its feasibility work to model potential abandoned coal mines and guide site selection. The broader trend shows pumped hydro remains a reliable, long duration storage option that can work in tandem with new battery technologies to stabilize future grids as renewables expand.

Conclusion

As solar and wind capacity grows, the need for long-duration, grid-scale energy storage becomes more pressing. Pumped hydro, particularly when implemented in repurposed mine sites, offers a compelling blend of efficiency, longevity, and scalability. Kidson demonstrates the potential to convert a mining legacy into modern clean energy infrastructure, while global researchers continue to refine the science, economics, and regulatory pathways necessary to realize similar projects worldwide.