Pumped Hydro in Australia -- State of Play 2025

Part 1: The Australian 60

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Pumped hydro is stumbling for the moment in Australia, but it will remain a major part of the energy storage paradigm given its high efficiencies, ability to provide synchronous inertia, and balance substantial amounts of variable, inverter-based wind and solar. While Borumba and Snowy 2.0 are large in power and duration most pumped hydro projects are modest in comparison.? Across Australia bluefields and mine sites dominate the list as they offer reduced civil costs and infrastructure access.?

Key Findings?

• There are over 60 pumped hydro projects across mainland Australia that have undergone site evaluation and consideration in the last 20 years.

• Projects considered for development are identified via brownfield opportunities and not geographic recommendations.?

• The Australian 60 sites have lower head and lower power outputs when compared to the premier sites identified in the Australian National University pumped hydro studies.?

• Blue fields and mine sites dominate the list highlighting the advantage of existing infrastructure and built reservoirs.?

• Sourcing of water for projects is not an impediment in project design factors.?

• Tasmania’s Battery of the Nation investigated power station conversions but ultimately focused on existing reservoir to existing reservoir options, though the preferred option to supply Marinus link is a new turkey’s nest linked to Lake Cethana?

• Nationally, the average head is just over three hundred metres – the minimum considered head by the Australian National University team led by Professor Andrew Blakers.?

• Site geology remains a significant challenge for pumped hydro projects.?

• Initial durations are being re-set down from 24 or 40 hours to 8-12 hours (with concomitant increases in power). The Mount Rawden project is an example of this.?

• Traditional Owner’s engagement seems to be well managed with most of the projects.?

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Introduction?

Energy storage is a major infrastructure and policy topic in Australia with pumped hydro part of the discussion. Within energy planning circles, the degree to which electro-chemical solutions will encroach into Australia’s long duration energy storage needs remains unclear given the uncertainty of how much system stability synthetic inertia can provide. And while there are many inferences made around setting long duration energy storage targets, the current gov’t and industry focus is on sub 4-hour duration solutions, most of which are lithium ion. ?

Pumped hydro is well proven form of mechanical storage, with low capital energy costs, zero system decay, and an ability to serve at intra-seasonal cycles – aspects that electro-chemical solutions do not have. Pumped hydro has multiple Achilles heels – long development cycles, bespoke equipment, siting limitations, and viewshed impacts to name the big ones. But it works reliably and has high round-trip efficiencies – key factors that decision makers place great primacy on. There is a clear consensus that while long or deep storage is not needed immediately, the long planning and construction horizons of pumped hydro are already pressing on 2035 targets.?

Over the last two decades established gentailers, developers (both established and start-ups), and government energy companies have initiated efforts to develop pumped hydro to support the NEM and WEM. ?

Initial research shows that there are over 60 (mainland Australia) pumped hydro projects that the author is aware of, which, in the last 20 years, have undergone desktop study or more by developers. This list excludes the twenty-one projects in Tasmania's Battery of the Nation (except Cethana), as well as projects under 30MW (Walpole, Bendigo, and Leneva). ?(This list has been aggregated from internet sources and conversations with other players in the industry. The author recognizes that the list is not complete and welcomes comments.)?? While Snowy2.0 is overly analyzed, this article will focus on the state of play in 2025 for pumped hydro projects either abandoned or in execution and what are some the factors impacting their development. ?

Water does not appear to be a development constraint. ?

Their type and size diverge from the assumptions and models derived from the GIS siting analysis conducted by academics and consultants. Those analysis looked globally (or regionally) and winnowed down sites based on geographic criteria. In truth, most of the projects that have received serious study are those that are more bottom up in nature – where existing infrastructure components offer the opportunity to reduce the capital costs (e.g., Kidston is built around a spent gold mine). ?

Overall, the initial findings show that external project factors are what hold projects back – an indicator as to the maturity of the technology. ?

The unresolved question for developers is compensation for long duration – this appears to be the factor holding them back from FID. To address this, developers are shortening duration. Projects initially touted in the 24–40-hour range are being scaled back to 8-12 hours (Mount Rawden is an example of this)?

Fortunately, developers are taking the engagement with Traditional Owners seriously – and in two cases, offering an equity stake. The initial data set shows only one project having been held up by Traditional Owner opposition.?

The Australian 60 list has now grown to 78 projects with an average head of 357 metres.?

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Types?

Simplistically, pumped hydro projects fall into four types: greenfield, bluefield, mine sites, and unconventional. (Academically there are seven types. Nor is there a formal cut-off on size. I use the informal Tractabel number of 30MW/300MWhr).?

Unconventional systems include seawater, subsea, subterranean, high-density fluids, and bladder bags. Currently, these are esoteric designs, but have merit where elevation is not available (e.g., coastal Europe). Seawater systems have garnered the most design and development interest to date. In Australia, the Cultana seawater project in South Australia was heavily evaluated and is included in the Australian 60 (we will discuss it in the oddballs’ section). High-density fluids show promise as their power output is a function of density allowing for higher power outputs at lower elevations. This technology seeks to be modular and may be well suited for mine sites in Western Australia.?

Greenfield sites are pumped hydro systems that involve two new reservoirs. Generally, this involves an upper reservoir in the form of a turkey's nest and a lower reservoir in the form of a gully embankment. These were the configurations that dominated the first global analysis by ANU.

Bluefield sites are those where at least one of the reservoirs is an existing reservoir. These configurations have the appeal of capitalizing on avoiding the civil costs of a reservoir and usually come with access to water. Bluefield configurations can be existing reservoir to existing reservoir (a commonly explored model) or existing reservoir to a new reservoir. Generally, the existing reservoir is the lower reservoir, though there are examples where the lower reservoir is the constructed reservoir. Hydro Tasmania thoroughly explored reservoir to reservoir options in their 2017 assessment across their assets. As an observation, bluefield projects that involve retrofitting existing power stations necessitate significant (and costly) engineering works - costs so debilitating it was dismissed out of hand by the Hydro Tasmania team.

Mine sites capitalize on pits and tailings dams as well as proximity to existing infrastructure and available workforce and services. In our definition this refers to just to surface pit mines, though underground mine workings have been considered for project development (e.g., Bendigo). Hard vs. soft rock is an important distinction in pumped hydro mine sites as daily hydraulic weight loading on soft rock can be problematical long term. Consideration of pumped hydro is a creative mine reclamation option being fully considered by mine operators and is heavily promoted within the Hunter Valley.

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Australian Pumped Hydro Developers

?Pumped hydro developers in Australia generally fall into three classes: Gentailers, state enterprises, and developers. Gentailers need the storage to accommodate their pivot to renewables and have the assets to do so. Energy Australia’s Lake Lyell is a clear-cut example as they manage Lake Lyell for their coal-fired power plant (Mount Piper) scheduled for closure in 2040. The same is true for AGL looking at conversion of their Bogong and McKay hydro assets. Zen Energy is also in this category as they are one of the new class of gentailers committed to delivering 100% renewable energy products to their retail customers – necessitating their need for deep storage.?

State Enterprises are exploring pumped hydro as they hold a trust responsibility on energy security and see pumped hydro as a solution to the emerging challenge of providing long duration energy storage for when renewables penetration exceeds 85%. They are setting policy targets around storage and facing questions of “how.” ?Queensland Hydro, Hydro Tasmania, and Synergy are examples here (with the SECV beginning to look in the direction of pumped hydro following their pioneer investment). Developers are either looking to develop and flip (Energy Estate, BE Power) or hold and operate (e.g., ATCO, Turnbull and North Harbour). ?

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Western Australia?

Western Australia is a low elevation state with few pumped hydro opportunities of significant elevation. Accordingly, the Blakers work set their minimum opportunity elevation for Western Australia at 200 metres compared to 300 metres for the eastern seaboard.?

The Darling Escarpment east of Perth offers excellent head as well as steep drops – ideal conditions. The escarpment currently offers a range of water storage facilities and was the focus of internal analysis by the State (The ANU team issued a paper focused on this potential). The State had GHD conduct a study and settled on five sites for further analysis (four bluefields and a mine site). However, as escarpments are ecosystem boundaries, they are ideal hunting and scouting points so the potential for encountering cultural heritage sites was high. Furthermore, the State had just been through the legislated confusion following the issuance and rescinding of the 2021 Aboriginal Cultural Heritage Act. As a result, they showed prudence and caution and did not proceed. ?

Recently the State clearly stated that they found Pumped Hydro to be challenging in terms of water and siting. ?In doing so upended Kerry Stokes Seven’s effort to develop the Muja mine site.? However, the State has maintained their agnosticism to long duration technologies. It is rumored that the State is looking at other sites of lower head. There are also several hard rock mining pits that various mining companies and independent developers are looking at. Given the low head aspects of the State, it has garnered the interest of the high density pumped hydro developers.

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South Australia?

Though a flurry of activity five years ago, South Australia now has no pumped hydro plans. However, ~2019 there were six projects on the burn across the State, none of which advanced to FID even though the State has been on an accelerated renewables uptake (even by Australian standards) and generous grant programs. One of the key drivers at the time (and now resolved) was their limited transmission connectivity with Victoria. The factors that set back the projects are varied from continued mining operations to social license, and a reluctant Defence facility. In dry SA, water has not been identified as an issue. Interesting of note is that the average head for SA projects was just over two hundred metres. Though all cancelled, these projects are worth taking a quick look at.?

Kanmantoo?

Kanmantoo is an open-pit copper gold mine 44km southeast of Adelaide that was approaching end of life. The owner, Hillgrove Resources, sold the pumped hydro rights to AGL in April of 2019. Assisted by ARENA funds, geotechnical investigations for the pumped hydro project identified additional ore deposits. On such findings Hillgrove decided to exit the pumped hydro strategy and continue mining operations – opening a deep mine in May of 2023. As with other mine sites, a rapid project timeline was envisioned. The team expected the full project timeline of development through to commissioning in 5 years. ?

?Middleback?

Zen Energy partnered with SIMEC to develop their Iron Duchess Mine located southwest of Whyalla proximal to Electranet’s 132kV line. The driver was not only storage for the grid as well as provide firming capacity for SIMEC’s mine as well as the Liberty Primary Steel facility in Whyalla. Transmission capacity issues, and South Australia’s summer temperatures triggered consideration of new transmission capacity leading to multiple options of 110, 220, and 330MW to be considered. They looked at larger energy options by planning larger hydraulic variation given the low (~200m) head. The mine pit was to serve as the lower reservoir and spoils were to frame the upper reservoir turkeys nest. Though the design limitation was the capacity of the Cultana-Yadnarie transmission line. Water losses through evaporation and pit losses would have been sourced from the existing water supply at the mine. The initial 3.8GL was to be sourced from SA Water from Whyalla, possibly requiring a ~40km transmission pipe.?

The initial plan was to develop the upper reservoir during the final years of operation of the mine and subsequently pivot to energy storage. Ultimately the project was scrapped by the mine owner.?

Highbury?

Tilt Renewables looked to develop Holcim’s Highbury quarry outside of Adelaide. Quarry operations ceased in 2009. Geographically favourable, the 300 MW project sought development approvals in 2018, but was abandoned by mid-2019. Of late the rock quarry has been discussed as an “adventure tourism destination water oasis.”?

Baroota??

Baroota was developed around a surplused SA Water reservoir outside of Port Augusta. AC Energy had acquired a 51% stake of UPC in 2018, announced the 250MW project in August 0f 2019 with the goal of “start building in the next six months”. By 2021 Rise Renewables was involved and the developers believed that construction would commence in 2022 and by operating by 2025. Reasons for the project cancellation remain unclear, but it may have run into challenges with securing Traditional Owner consent as well as endangered species issues. Anecdotally it would appear that developers seeking to build on existing mine sites had predicted a three-year construction period and a short period to securing FID.?

Goat Hill?

Goat Hill (also referred to as Lincoln Gap) was proposed by the now defunct Australian/Chilean developer Altura (with support from Sunset and Delta – owners of Vale Point). ?The site, 12km west of Port Augusta would have fed into the 275kV network near Davenport – requiring 18km of new transmission line. They would have sourced water from SA Water’s Morgan Whyalla Pipeline with a new 9km water pipeline. The project was a closed loop greenfield project requiring both reservoirs to be constructed – the developer anticipated construction to commissioning in 3 years. ?This project conducted full and extensive geo-tech and environmental studies.

?This concludes Part 1 of this article. In the next installment I will look at micro and unconventional systems, siting factors, Victoria and Tasmania.

Author: Lawrence Molloy

My PhD research is focused on pumped hydro energy storage and long duration energy storage policy in Australia. As a first step in this research, I am assembling a database on the various pumped hydro projects that have been explored in Australia. Here are some initial observations* (* disclaimers abound – this is a work in progress, comments and corrections are most welcome)

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