Global study highlights urgent role for underground pumped storage in Net Zero transition
Source：water power magazine
A new report on long-duration energy storage (LDES) concludes that underground pumped storage hydro (PSH) will be critical to integrating renewable energy into future grids and achieving Net Zero.
Prepared by hydropower engineer Mike McWilliams, the study finds that global electricity storage must grow from around 2,000 GWh today to more than 100,000 GWh by 2060. This represents a fifty-fold increase within 35 years – equivalent to building as much storage in the next three decades as in the previous century.
The report stresses that alongside storage, electricity systems will require a wide range of grid services to remain stable, secure and affordable as variable renewable generation expands.
While multiple technologies will be needed, the analysis concludes that pumped storage hydro is best suited to deliver the majority of long-duration storage and grid services. Conventional PSH already provides more than 80% of existing electricity storage worldwide, but development is often constrained by site availability, environmental concerns and long permitting timelines.
Underground PSH, by contrast, offers modular, location-agnostic deployment. Facilities can be built almost anywhere, scaled from 500MW up to several gigawatts, and provide storage durations expandable from 8 to more than 24 hours. The report finds that only underground PSH meets the combined requirements of gigawatt scale, economic viability, modular design, broad siting potential and storage durations of 20 hours or more.
Zero Terrain’s underground pumped storage project at Paldiski, Estonia, is highlighted as a demonstration of this approach. Fully permitted and ready for construction, the project is designed for 500MW capacity with an initial 8 hours of storage, expandable to 20–40 hours. A deep-underground variant, based on 1400m shafts, is also described, offering greater efficiency, reduced water use, and suitability for deployment in water-stressed regions.
The study also identifies regulatory barriers. It notes that deregulated electricity markets often struggle to properly value and procure the multiple services required for renewable-based grids, and argues that formal system planning is needed to optimise deployment of LDES technologies such as underground PSH.
The report concludes that large-scale, modular pumped storage is essential to meeting decarbonisation targets while ensuring secure and affordable electricity. Without it, progress towards Net Zero will be slower, electricity costs are likely to rise, and supply security may diminish.
The full report and executive summary, The Global Need for Underground Pumped Storage Hydro, are available at www.mcw-e.com.