Origin to “significantly extend” storage capacity of Australia’s biggest battery, to cover evening demand peak

Origin Energy has approved a further $80 million expansion of what will be – at least for a time – the biggest battery storage project in Australia, built at the site of the country’s biggest coal generator, Eraring.

Origin said on Thursday that the newly committed fourth stage of the project would “significantly extend” the battery’s dispatch duration to help cover the evening demand peak on the New South Wales grid, which is expected to say goodbye to all its remaining coal generators over the next 10 years.

Across all four stages, Origin says the total size of the Eraring battery will now be 700 megawatts (MW) and 3,160 megawatt-hours (MWh), providing 4.5 hours of storage on average. 

“This next stage of the Eraring big battery adds 360 MWh of storage, building on the work now underway and strengthening the site’s status as the largest approved battery energy storage system in the Southern Hemisphere,” Origin’s head of energy supply and operations, Greg Jarvis, said in a statement.

“When complete, Australia’s largest power station site will host the nation’s largest approved battery storage system, reinforcing Eraring’s role as critical infrastructure at the centre of Australia’s energy system for decades to come.”

Source: Origin Energy

The gentailer says construction of the $80 million stage four expansion will begin before the end of the year and is anticipated to come online in the first quarter of the 2027 calendar year.  The commitment comes as battery storage costs continue to fall by more than 40 per cent in the last year.

As Renew Economy has reported, the evolution of Eraring has been mired in controversy, largely because of the decision by the NSW government to effectively underwrite the ageing coal fired power station’s operations until 2027 at a cost of up to $450 million.

Origin had announced in 2022 the planned “early closure” of Eraring in late 2025. But its failure to invest in any new capacity, and the lack of sufficient investment elsewhere in the grid, more or less forced the hand of the state government, anxious to avoid price spikes ahead of the next state election.

Since landing that underwriting agreement, Origin has quickly accelerated its investment in battery projects, and has started to move forward on some large scale wind projects too.

Apart from Eraring, it has committed to another big battery – 300 MW and 650 MWh – next to its Mortlake gas-fired power generator in Victoria.

It also has a “tolling” agreement for the off take of the 500 MW and 1560 MWh Supernode battery in Queensland that will come online in early 2026 and which will ultimately take the Eraring’s battery title as the biggest in the country.

Jarvis said on Thursday that Origin has committed to developing or contracting 1.7 GW in owned and tolled large-scale battery projects, including at Eraring, Mortlake Power Station in Victoria, the Summerfield battery storage project in South Australia and the Supernode battery in Queensland. 

It has also bought the huge 1.4 GW Yanco Delta wind project in the south-west of NSW, and is advancing other wind and solar projects.

Battery equipment for stage four of the Eraring battery will be supplied by Finnish technology group Wärtsilä and design and construction services will be provided by Enerven, consistent with the rest of the project.  

See also this updated story: Australia’s 10 biggest battery storage projects – and what they are paid to do

And also Renew Economy’s Big Battery Storage Map of Australia

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