The battery of the future does not always look like a battery.
Sometimes, it looks like water sitting on a hill, waiting for dinner time.
That is the appeal of pumped hydro: use electricity to lift water when power is plentiful, then let gravity help return that energy when it is needed. The machinery is well established. The challenge is finding a place where the engineering, environment and economics work together. US Department of Energy’s explainer
One Australian proposal bringing that challenge into focus is EDF’s Wala Wala project in the Dungowan Valley, near Tamworth in New South Wales. EDF’s project website describes a 300-megawatt scheme with up to ten hours of storage. Its more recent federal referral considers a larger design range. EDF’s project overview
The referral drew fresh coverage on 7 September 2026. The official record says the referral began on 20 August 2026 and lists it as open for public comment. This is a development and environmental-assessment milestone—not an operating power station or a construction approval. Energy-Storage.News reporting, federal project notice
Charging a hill, then getting the energy back
Imagine two reservoirs at different heights.
To charge the system, pumps move water into the higher one. To discharge it, water travels downhill through turbines connected to generators, producing electricity. The water collects below, ready for another cycle.
The energy is stored in the water’s elevated position. There is no chemical battery cell and no need for a newly discovered material. Pumped hydro is an established form of large-scale storage. US Department of Energy
There is an important catch: the plant uses more electricity to pump water uphill than it returns downhill. Equipment supplier GE Vernova describes a typical overall cycle efficiency of about 80%. As an illustration, that means roughly 80 units returned for every 100 put in—not a performance guarantee for Wala Wala. GE Vernova’s technical overview
That loss does not make storage pointless. Its value comes from moving energy to a more useful time. A surplus at lunchtime cannot cook dinner after sunset unless something stores it or another generator supplies it.
What ten hours actually means
The federal referral proposes 300–400 megawatts of output with ten hours of storage, using two new off-river reservoirs and an underground powerhouse. Wala Wala referral summary
Those numbers describe different things:
| Measure | In everyday language |
|---|---|
| Megawatts (MW) | How quickly the plant can deliver electricity |
| Megawatt-hours (MWh) | How much electrical energy it can deliver over time |
| Ten-hour duration | The intended length of discharge at the stated output, starting with sufficient stored energy |
Multiplying the proposed output by ten hours gives 3,000–4,000 MWh, or 3–4 gigawatt-hours. That is a calculation from the design figures, not measured performance.
It would be substantial storage for shifting power across part of a day. It would not mean unlimited electricity, or enough storage to cover every prolonged spell of poor renewable generation.
The water question is not a footnote
“Off-river” sounds reassuring, but it does not mean “no water supply needed”.
The referral says sourcing is still being investigated, with Dungowan Dam likely to provide at least some of the water. It says direct extraction from Dungowan Creek is not being considered. Final arrangements depend on studies and discussions with the council, existing users and the community. Federal referral
EDF’s published community responses acknowledge questions about initial filling and subsequent top-ups, dam safety, local traffic and biodiversity. The company also reports initial survey findings of an endangered woodland ecological community. These are the developer’s disclosures, not a regulator’s conclusion that the impacts are acceptable. EDF’s community questions and responses
For nearby residents, a national energy benefit and a local environmental cost can exist at the same time. A credible assessment has to examine both. Calling something a water battery does not make the roads, reservoirs or construction disappear.
This is a plan for the 2030s
The referral anticipates main construction beginning in early 2029, subject to approval, with operation from the end of 2033. Those are proposed dates, not commitments that the plant will be available then. Federal referral and proposed schedule
EDF’s public project-status page likewise describes planning, consultation and studies. Its scoping process is intended to establish what environmental and social investigations are required. It does not establish that the project has passed them. EDF’s project-status page
For readers following the project, the useful milestones are therefore quite practical: completed assessments, a settled water strategy, permissions, a workable grid connection and a deliverable construction plan. The impressive storage number is only the beginning of that story.
Gravity still deserves a place in the energy conversation
Wala Wala is interesting because the proposed technology is understandable: lift something heavy, then recover some of the energy as it falls.
Its potential contribution is to make electricity available at a different time from when it was generated. Its test is whether that service can be delivered at this particular site with acceptable costs and impacts.
The future of energy storage will be judged by more than laboratory breakthroughs. Sometimes the decisive work is in a valley: understanding its water, its geology and the people who already live there.
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