Global Atlas of potential pumped hydro energy storage sites informs national renewable energy strategies

In 2025, ACAP-supported research at ANU materially shaped how governments, utilities and developers plan long-duration energy storage. The Pumped Hydro Energy Storage (PHES) Atlases, led by Professor Andrew Blakers and supported by ACAP, are now embedded in national strategies and commercial pipelines across multiple continents – accelerating the pathway to ultra-low-cost solar (ULCS).

Solving solar’s storage constraint

Ultra-low-cost solar depends on one critical factor: storing abundant daytime generation and delivering it reliably at scale. Off-river pumped hydro energy storage (PHES) is the lowest-cost form of long-duration (16-160 hour) storage, while batteries cover short term (1-8 hour) storage. Since 2016, ANU’s PHES Atlases program has systematically mapped its global potential.

The Atlases identify 820,000 potential off-river sites worldwide – representing storage capacity equivalent to approximately two trillion EV batteries. Using high-resolution elevation data, the team calculates reservoir geometry, storage volumes, head height and indicative costs, producing consistent open-access global datasets. The analysis demonstrates that at least 50 times more viable sites exist than previously recognised [3].

This work builds on foundational research into 100% renewable electricity systems [1], integration of pumped hydro in fully renewable grids [2], and the Global Atlas of Closed-Loop Pumped Hydro Energy Storage [3].

In 2025, the methodology was extended to bridge pixel-level renewable siting data with regional planning, strengthening system-level decision-making [4].

Batteries provide short-duration, high-power storage while PHES provides long-duration, low-cost bulk storage. Together, hybrid PHES–battery systems enable full replacement of gas peaking plant. The Atlases therefore can guide removal of a central technical barrier to renewable-dominated grids. Pumped hydro also increases transmission utilisation, enabling power lines to operate near full capacity day and night.

Shaping Australian infrastructure decisions

The PHES Atlases have directly influenced major Australian storage developments. Former Prime Minister Malcolm Turnbull credited ANU’s mapping with overturning assumptions about limited hydro potential, helping underpin Snowy 2.0 (2.2 GW, 350 GWh).

A NSW Government feasibility study for suitable pumped hydro sites in the state involved a detailed review of the potential locations identified in the PHES Atlas maps and several hundred site options within the NSW Government’s Renewable Energy Zones were identified.

Two NSW pumped hydro projects currently in planning stages used analysis of the PHES Atlases to identify their sites and secured Long-Term Energy Service Agreements in February 2025, and were declared Critical State Significant Infrastructure in February 2026:

·      The ACEN Australia Phoenix Pumped Hydro energy storage project (Yarrabin) in Central West Orana Renewable Energy Zone NSW will have the capacity to power 600,000 homes and businesses with a target storage of 12 hours (0.8 GW, 12 GWh).

·      The Zen Energy $3.5 billion (1 GW), Western Sydney Pumped Hydro Project at Lake Burragorang is projected to power 500,000 homes and buisnesses for more than 8 hours.

In Queensland, Atlas outputs informed the SuperGrid Infrastructure Blueprint and assessments of Pioneer-Burdekin (5 GW, 120 GWh) and the in-progress Borumba project (2 GW, 50 GWh).

Accelerating global uptake of the Pumped Hydro Energy Storage Atlases in 2025

International engagement intensified in 2025. The RE100 mapping platform and PHES Shortlisting Tool attracted thousands of users, with more than 700 site-specific submissions lodged this year alone.

The Pumped Hydro Energy Storage Atlases identify 820,000 potential off-river sites worldwide – representing storage capacity equivalent to approximately two trillion EV batteries.

Professor Blakers delivered a plenary address at the International Forum on Pumped Storage Hydropower at UNESCO headquarters in Paris and presented renewable grid optimisation research at PVSEC 2025. With support from DFAT, the team conducted technical workshops and policy briefings across ASEAN, including Indonesia, Malaysia, Thailand, Laos, Cambodia and Vietnam.

Major international organisations are embedding Atlas outputs into formal planning processes. The World Bank circulates PHES Atlas results among hydropower specialists, and the International Hydropower Association has credited the work with materially improving long-term grid planning.

In India, the Ministry of Power directed utilities to examine Atlas-identified sites, and tenders in Andhra Pradesh reference Atlas data. The U.S. National Renewable Energy Laboratory incorporated ANU’s geospatial methods into national supply-curve modelling. Developers across North and South America are using the datasets for feasibility analysis.

As argued publicly in 2024, large-scale storage is no longer the limiting factor in energy transitions [5]. The Atlases provide the technical proof.

Sustained support and scale

The program began with ARENA funding (2016–2021), establishing its core methodology. Ongoing ACAP/ARENA support (2023–2030) and DFAT/Australian Water Partnership funding (2022–2025) enabled global expansion. A 2025 Prospera grant supported detailed site selection in Indonesia. Total CPI-adjusted funding exceeds $4.4 million.

System-level impact of off-river pumped hydro energy storage Atlases

Off-river pumped hydro is not simply a storage option; it is a system enabler for ultra low-cost solar. By delivering transparent global mapping, open datasets and sustained international engagement, ACAP-supported PHES research has shifted storage from perceived constraint to proven opportunity – enabling countries to plan confidently for solar-dominated energy systems.

Link to Pumped Hydro Energy Storage Atlases – https://re100.eng.anu.edu.au/pumped_hydro_atlas/

References

[1] Blakers, A., Lu, B. & Stocks, M. (2017). 100% renewable electricity in Australia. Energy 133, 910–920. https://doi.org/10.1016/j.energy.2017.05.168

[2] Blakers, A., Weber, T. & Silalahi, D. (2025). Pumped hydro energy storage to support 100% renewable energy. Progress in Energy 7, 022004. https://doi.org/10.1088/2516-1083/adaabd

[3] Stocks, M., Lu, B., Cheng, C. & Blakers, A. (2021). Global Atlas of Closed-Loop Pumped Hydro Energy Storage. Joule 5, 270–284. https://doi.org/10.1016/j.joule.2020.11.015

[4] Cheng, C., Blakers, A., Weber, T., Catchpole, K. & Nadolny, A. (2025). High-resolution siting of utility-scale solar and wind: Bridging pixel-level costs and regional planning. Energies 18, 4361. https://doi.org/10.3390/en18164361

[5] Rüther, R. & Blakers, A. (2024). Energy storage is a solved problem. PV Magazine, 8 October 2024. https://www.pv-magazine.com/2024/10/08/energy-storage-is-a-solved-problem/

Professor Andrew Blakers (ANU) visiting the Nant de Drance pumped hydro energy storage facility in Switzerland (0.9 GW, 20 GWh).