Origin adds more storage to Eraring battery, making it biggest in Australia and one of world’s largest

Origin Energy has announced a third stage to the giant battery at Eraring, ensuring that the site of Australia’s biggest coal generator is transformed into the country’s biggest battery, and one of the biggest in the world.

The company announced on Thursday that the new expansion will add 700 megawatt-hours of storage, essentially turning the first stage of the project from a two hour battery rated at 460 MW and 1070 MWh, into a four hour battery rated at 460 MW and 1770 MWh, making it better suited to feed into the extended evening demand peaks.

That component will be completed by the end of next year, including the expanded storage capacity, while the previously announced second stage of 240 MW and 1030 MWh is due to be on line in 2027.

That will take the total facility to 700 MW and 2,800 MWh – the size originally contemplated when the Eraring battery plans first took shape.

It will make Eraring the biggest battery in Australia, overtaking the Neoen Collie battery (560 MW, 2240 MWh) that is also under construction, the biggest in the southern hemisphere and one of the biggest in the world, although some projects in the planning are potentially five times the size.

Origin’s head of energy supply Greg Jarvis says the battery will cement Eraring’s importance to the grid for decades to come.

“The scale of this project is impressive,” he said in a statement.

“The site, at more than 17 hectares, is equivalent in area to 24 soccer fields and once complete, it will host more than 2,000 individual battery enclosures and some 180 kilometres of cabling.

“At 2,800 MWh, when cycled once a day, the Eraring battery will dispatch enough energy to power more than 150,000 NSW households annually, helping to firm variable supply from wind and solar.”

An Origin spokesperson told Renew Economy that expanding an existing storage project made more sense because it enables economies of scale, and avoids any potential future outages to extend storage duration at a later date, once in operation. It will involve the addition of another 560 battery enclosures.

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 planned spending in wind, solar and battery projects.

Apart from Eraring, it has committed to another big battery – 300 MW and 650 – next to its Mortlake gas-fired power generator in Victoria, and has a “tolling” agreement for the off take of the new 500 MW, 1560 MWh Supernode battery in Queensland that will come online in early 2026.

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.

The Eraring battery is being supplied by Finnish technology group Wärtsilä and design and construction services will be provided by Enerven, consistent with the rest of the project.

Origin says the 40 year-old Eraring coal plant is now scheduled to close in August 2027, as part of the agreement with the NSW government – although its official closure date has been pushed out to early 2029.

See also Renew Economy’s Big Battery Storage Map of Australia.