Repurposing decommissioned mining infrastructure for energy storage represents a compelling opportunity to maximize existing assets while supporting ecological remediation of industrial sites. This preliminary study examined the technical and economic feasibility of an underground pumped-storage hydropower (PSH) system utilizing Budryk Shaft II, an abandoned mine shaft in Poland, as the lower water reservoir.
The design integrates a vertical Pelton turbine rated at 5.3 megawatts, operating across a gross head of 900 meters with a net design head of approximately 838 meters. The system utilizes a working water volume of 12,000 cubic meters and couples the turbine to a 6.3 kilovolt synchronous generator. This configuration enables discharge flow of 0.71 cubic meters per second during generation.
Pumping energy requirements were calculated across three stages, totaling approximately 64 megawatt-hours. The turbine shaft can deliver roughly 24.8 megawatt-hours of mechanical energy over an operating window of 4.7 hours. This yields an upper-bound energy return ratio of 38.8 percent, though this represents preliminary estimates subject to significant refinement.
The study reveals both opportunities and limitations. The abandoned shaft provides immediate infrastructure, eliminating extensive excavation typically required for new underground reservoirs. However, multiple critical unknowns remain. Generator efficiency data were unavailable during assessment, preventing accurate calculation of electrical output and round-trip efficiency. Pump operating points require verification under actual operating conditions, and hydraulic transient behavior during rapid load changes needs detailed modeling.
Additional work must address shaft sealing integrity, structural load capacity, auxiliary energy demand from monitoring and control systems, and final hydraulic connections to an upper reservoir. These factors will ultimately determine whether the site can achieve the 75-80 percent round-trip efficiency typical of modern PSH facilities.
This feasibility study demonstrates a viable pathway for converting industrial legacy sites into modern energy infrastructure while supporting circular economy principles in the energy sector.
