Alinta Energy has cancelled development of the 900 MW Oven Mountain pumped hydro energy storage project in New South Wales, removing one of Australia's largest proposed long-duration storage assets from the pipeline.
The decision was announced on 22 October following an assessment of construction economics and infrastructure requirements.
An eight-hour, 7,200 MWh design
The proposed A$1.8 billion project was designed to provide approximately 7,200 MWh of electricity storage, equivalent to eight hours of discharge at full output. It was to be built near Armidale in northern New South Wales and was intended to support renewable generation on the grid.
Why pumped hydro keeps stalling
Pumped hydro is the oldest form of long-duration storage and still offers the largest energy capacity per site, but it requires specific topography, water access, transmission connections and very long construction schedules. Those characteristics make projects highly sensitive to construction cost inflation and to the economics of the market they would serve — the factors Alinta cited in its assessment.
The cancellation also highlights a structural tension in the energy transition: the storage technologies with the deepest duration — pumped hydro and other multi-day options — are frequently the hardest to finance and build, while shorter-duration lithium-ion systems continue to dominate new installations.
What is left in the pipeline
Australia's storage build-out continues to lean on grid-scale batteries and on the Snowy 2.0 pumped hydro scheme, but the loss of Oven Mountain removes 7,200 MWh of eight-hour capacity that had been planned to serve multi-hour balancing needs, including absorbing surplus solar output and covering evening peaks.
For developers, the message is that headline duration alone does not make a project bankable. The Oven Mountain decision will be read closely by other long-duration storage proponents weighing capital-intensive builds in a market where revenue certainty remains a central question.
This article was assisted by AI analysis. Please refer to the original source for official information.