Last of 1,038 Wärtsilä Quantum units installed at big battery next to gas plant in coal country

A four-hour big battery being built in Victoria’s Latrobe Valley to help replace EnergyAustralia’s Yallourn coal power plant, which closes in 2028, has hit a major milestone, with all of its more than 1,000 Wärtsilä battery units now in place.

The 350 megawatt (MW, 1,400 megawatt-hour (MWh) Wooreen Energy Storage System (WESS) is being developed next door to EnergyAustralia’s Jeeralang gas power plant in the heart of Victorian coal country.

EnergyAustralia , one of Australia’s three biggest privately owned utilities, broke ground on the $700,000 million project in February of 2025, hailing it as “the biggest single investment” the company has ever made.

In July, it sold a 50 per cent share in the WESS project to Banpu Energy Australia, the local subsidiary of the Thai energy giant, for about $110 million. EnergyAustralia is still building and operating the project, as well as leading community engagement.

Wooreen is using Finland-based Wärtsila batteries and smarts, with the balance of plant for project being delivered by Zenviron, which announced the project’s latest milestone on Tuesday.

Wärtsila is also supplying Australia’s biggest battery, at Eraring in NSW where the country’s biggest coal fired generator is due to close in 2029, but has recently sold its battery division into a new joint venture because of low margins and the lack of new orders in the past year.

“The 1,038th and final Wärtsilä Quantum unit was safely delivered and installed recently, marking the completion of all battery installations on the project,” Zenviron said on LinkedIn.

“A fantastic achievement by the entire team, EnergyAustralia and project partners. Thanks to everyone involved for their commitment to safe, efficient and high-quality delivery as we continue progressing this landmark energy storage project.”

The installation of the Wooreen battery next to Jeeralang – a nearly 50-year old gas peaking plant that has an increasingly niche, but still important, role in stabilising the grid – is symbolically significant. The old and the new, side by side.

“It marks the next step in the Latrobe Valley’s energy journey and evolution from legacy coal to becoming a new type of energy powerhouse for our state,” Victorian energy minister Lily D’Ambrosio said at the project’s launch.

The Wooreen battery is scheduled for completion in 2027.

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