Queensland government-owned generator Stanwell has kicked off commercial operations at its 300 megawatt, two-hour Tarong Battery in the state’s South Burnett region, where it will supply essential firming capacity and reliability “within fractions of a second.”
Stanwell announced the milestone late last week, celebrating the 600 megawatt-hour battery as its “first dispatchable energy storage project;” albeit located in the shadow of the Tarong coal power station.
“This is a significant milestone for Stanwell, our first wholly owned battery project, delivered end-to-end by our team from concept through to construction, operations and maintenance.” Stanwell CEO Michael O’Rourke said in a statement.
“The 300 MW battery will store energy during periods of high generation and then release it into the grid during periods of high demand, responding within fractions of a second to provide essential firming capacity and reliability,” O’Rourke says.
“Stanwell’s deep experience operating and maintaining reliable coal-fired power stations is powering a broader vision, to build a more flexible and reliable energy portfolio to meet Queensland’s growing energy needs.”
The Queensland government also marked the occasion, describing it as “another major milestone” in the state’s Energy Roadmap, just days after the offical powering-up of CleanCo’s Swanbank Battery south of Brisbane.
“Batteries for firming and storage are critical to our Energy Roadmap delivering affordable, reliable and sustainable energy for Queensland,” state energy minister and treasurer David Janetzki said.
“This project will strengthen energy reliability and support peak demand, easing network stress and improving overall market efficiency.”
Indeed, the reliability of Queensland’s coal plants could do with some strengthening, considering an average of 26% of the state’s coal power capacity was found to have been offline from April to September of 2025.
According to recent analysis from Reliability Watch, Queensland coal power had 69 outages, including 61 unplanned breakdowns, over the course of winter – a period where lower overall demand means coal plants are under less pressure and should be less prone to breakdowns.
The worst performer was the 49 year-old Gladstone power station, which had 33 unscheduled outages over the six months. The worst performing units were Gladstone 1, Tarong North, Millmerran 2, Callide C3, all being available less than 50% of the time.
Tarong North had the lowest availability, offering on average only 33% of its capacity to the market, due to being offline for a planned outage.
Stanwell says the $514 million Tarong battery’s 164 lithium-ion Tesla Megapacks will boost the co-located coal plant’s overall capacity to 2.1 GW and transform it into the single largest generating site in Queensland.
It will be operated using Tarong power stations’ management and operating systems.
Tarong battery joins the state’s other completed utility-scale battery projects, including Swanbank, Wandoan South, Bouldercombe, Chinchilla and Western Downs.
Still to come is 300 MW, 1,200 MWh Stanwell battery, which is also being built next to an existing coal fired power station and aims to be operating by mid 2027 – part of Stanwell’s plans to have 5 GW of battery storage built and contracted by 2035.
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*This article has been amended to clarify that the lack of availability of the Tarong North coal plant over the April-September period on 2025 was due to a planned outage.
