Corrected 3 October 2026. When this story was first published the dateline above wrongly read 18 August 2026, with a source line about a Snowy Hydro page that belongs to a different story. It was published on 3 October 2026 from the EnergyCo sources listed below. No fact in the story changes.
The Waratah Super Battery at the old Munmorah power station site is now running at full capacity.
The NSW Government announced on 28 September that it is now fully operational
after the
Australian Energy Market Operator approved it to run at full capacity. It is a large battery, but the
size is not the interesting part. It was built to let the existing transmission network carry more
electricity, and it reached full operation about nine months after the end of the year EnergyCo had
given for it.
What it is for
EnergyCo describes the project as more than just a battery
. Alongside the battery it includes
an overarching control system
, arrangements for paired generation services
and
upgrades to the state's existing transmission network
. Together, it says, these let the project
act as a shock absorber
when lines trip because of lightning, bushfire or fallen trees.
The practical effect is set out in EnergyCo's 2025 release: the project will allow more power to
flow from existing generators to supply electricity to people around the state and is faster to
implement than new transmission lines
. In other words, a large part of its job is getting more out of
the wires already strung, by standing ready to cover a sudden outage.
The headline numbers, and the guaranteed ones
The government's release gives the battery's capability as 850 megawatts of power and 1,680
megawatt hours of storage. EnergyCo's project page uses those figures as expected
capacity and
then sets a floor beneath them: an active capacity of at least 700 MW and guaranteed usable storage
capacity of at least 1,400 MWh
. Both are on the record: the first is the expected capacity, the
second the guaranteed minimum.
How long the last half took
Akaysha Energy, which built and operates the battery, started construction in May 2023 and finished
it in October 2024, according to the project page. On 5 August 2025 EnergyCo announced that the first
350 megawatts was online and that The remainder of the battery's capacity (for a total of 850
megawatts / 1680 megawatt-hours) is expected to come online later this year.
The project page later moved that to expected to be fully operational during 2026
. Full
operation was announced on 28 September 2026. Measured against the end of 2025, the year EnergyCo
named in August 2025, full operation came about nine months later. Neither the release nor the project page
says why it took longer.
Our view
The battery working at full capacity is good news for the Hunter and Central Coast grid, and the release is right that it matters more as coal stations close. But the delay is worth a sentence from the people who announced the earlier date. A project whose job is to let the network run harder is one whose timing other plans depend on, and "later this year" in 2025 becoming September 2026 deserves an explanation in the same place the first date was given.
How we did this
Every quoted passage is from EnergyCo: the 28 September 2026 joint ministerial release on its site, the project page, and its 5 August 2025 release and notice. The nine months is our measure from the end of 2025, the year named in August 2025, to the 28 September 2026 announcement; the battery may have been close to full capacity before the announcement. We did not contact EnergyCo, Akaysha Energy or Transgrid. The “our view” paragraph is opinion based on the documents quoted.
Sources
- NSW Government (joint ministerial release, published by EnergyCo), NSW flicks the switch on one of the world's most powerful batteries (28 September 2026, read 3 October 2026): full operation, AEMO approval, the 850 MW and 1,680 MWh figures and the parties.
- EnergyCo, Waratah Super Battery Project (project page, read 3 October 2026): the project's parts, expected and guaranteed capacity, construction dates and the 2026 operation expectation.
- EnergyCo, Waratah Super Battery Project begins partial operation as shock absorber for NSW grid (media release, 5 August 2025, PDF, read 3 October 2026): the first 350 MW, the "later this year" expectation and the more-power-from-existing-generators purpose.
Have we misread EnergyCo's pages, or is there an update? Tell us and we will check it against the source and log the outcome here.