Unlocking the potential of coal-mine water: research progress and future frontiers in arid Western China

Abstract Resolving the critical nexus between scaled coal mining and acute water scarcity in Western China, this review highlights the research progress and paradigm shifts in mine-water protection and utilization technologies. Key advances in coal-mine underground reservoirs are summarized—a flagship technology enabling long-term, large-volume water storage in mined-out spaces—as well as those for open-pit mines. It also elucidates coal-mine underground reservoir in situ purification governed by the water–rock–microorganism mechanism and that adaptability of treated mine water for ecological restoration. Research priorities addressing the bottlenecks of storage safety are proposed for integrated sensing-control systems and coordinated aquifer-slope construction. Future perspectives on multifunctional coal-mine underground reservoirs include carbon sequestration, pumped energy storage, and green hydrogen production. The transition from the conventional “prevention–blockage–containment” framework to a “diversion–storage–utilization” strategy marks a conceptual breakthrough in the field. Confronting the challenge of repurposing >5 billion tons of underutilized mine water annually in China marks a critical milestone toward green coal mining and sustainable development in the nation.