The biggest battery on Australia’s energy grid is now on standby as a shock absorber to prevent blackouts in New South Wales.
The Waratah Super Battery will also allow NSW to use and transmit more energy, applying further downward pressure on electricity prices, experts say.
The battery, built on the site of the former Munmorah coal-fired power station on the Central Coast, has added 350MW of battery capacity to the energy grid since plugging in last September.
Waratah’s backstop system was brought online on Friday, making it the largest energy system integrity protection scheme (SIPS) in the country.
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The NSW energy minister, Penny Sharpe, said the battery was a crucial addition to state infrastructure.
“As it comes online, it will help power our homes and businesses while stabilising the grid to avoid blackouts,” she said.
In the event of blackout risks or power surges from bushfires, lightning strikes or other disruptions, the battery would activate as a shock absorber and steady the state’s energy supply, Ahmad Ebadi, a senior project manager at Transgrid, said.
“[The battery system] monitors 36 transmission lines in real time across NSW, detects overloading and responds in seconds … to increase generation,” he said.
More power could be transmitted and used across NSW once the battery’s full capacity of 850MW comes online; that is expected by the end of 2025.
Operating at full capacity, the battery would ease the urgency of building more energy transmission, said Dylan McConnell, an energy systems researcher at UNSW.
“By increasing the utilisation of your existing transmission network, you can actually reduce the need to build more transmission in the future,” he said.
“Ideally, it [means] lower electricity prices in the long run.”
An agreement with the NSW government will mean the battery reserves 700MW of its capacity for the system-protecting service during the day in summer. Waratah can store and discharge energy like other big battery projects.
The project was one of 12 battery systems to enter the national energy market in the year to June – more than doubling grid-scale battery discharge, the Australian Energy Market Operator (Aemo) reported in July.
Investment in big batteries has accelerated in 2025. More projects are under construction, including one at Eraring, the site of the nation’s biggest coal-fired power station, and another at former coal plant Liddell.
The NSW government in 2024 extended Eraring’s operations to 2027 after Aemo in 2024 warned its retirement would increase blackout risks. More coal-fired power stations are scheduled to retire in coming years.
Anna Freeman, acting chief policy and impact officer at the Clean Energy Council, said the Waratah battery would help reduce the state’s reliance on coal.
“[It] is capable of holding as much energy as half an Eraring coal-fired power station and plays a pivotal role in ensuring that NSW can push ahead with confidence to a future powered by renewables,” she said.
Tim Buckley, the director of Climate Energy Finance, said the battery’s delivery could help bring energy prices down by supporting more green energy projects to completion.
“It will [help] more wind and solar and firming capacity into the grid, all of which means we will see electricity prices stabilise and then progressively, hopefully come down over time,” he said.
