Origin Energy (Origin) has approved the third stage of its large-scale battery at Eraring Power Station, adding further storage capacity to the project already underway and delivering the largest total dispatch duration of an operating battery or project under construction in the Southern Hemisphere.

The third stage of the Eraring battery will add 700 MWh to the 460 MW / 1,070 MWh first stage already under construction, increasing its dispatch duration to approximately four-hours. With the 240 MW / 1030 MWh second stage of the project also under construction, the combined energy storage of the Eraring battery will be 700 MW / 2,800 MWh, making it one of the largest battery energy storage systems in the world.

This latest investment in the battery at the Eraring Power Station site represents a further acceleration in Origin’s strategy to grow storage in its portfolio to help keep the grid stable as it supports increasing growth in variable renewable energy.

Origin has committed to 1.0 GW of large-scale battery capacity across its projects at Eraring and Mortlake Power Station in Victoria, along with tolling agreements for the offtake from Queensland’s 500 MW Supernode battery, which will begin to come online in the first half of the 2026 calendar year.

Origin’s head of energy supply and operations, Greg Jarvis said, “Construction of the third stage of the Eraring battery further increases our energy storage footprint and represents another significant step in our ambition to lead the energy transition through cleaner energy and customer solutions.

“The scale of this project is impressive. 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.

“Transforming the Eraring site to play an important role in contributing to the reliability and security of electricity supply as we progress through the energy transition is a priority for Origin. Upon completion, Australia’s largest power station will be host to the nation’s largest approved battery storage system, cementing Eraring as a critical piece infrastructure at the heart of Australia’s energy system for decades to come.

“The global scale of the battery storage system under construction and the incredible work our highly skilled teams and contractors are undertaking is something the region can be incredibly proud of,” Mr Jarvis said.

Stage three is anticipated to come online alongside Stage one at the end of calendar 2025. Stage two is anticipated to come online in the first quarter of the 2027 calendar year.

Battery equipment 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.

Alongside the large-scale battery under construction at Mortlake Power Station in south-west Victoria, this third stage takes Origin’s committed investment in owned storage in the portfolio to approximately $1.7 billion. The grid-forming battery at Mortlake, adjacent to the largest gas-fired power station in Victoria, is expected to come online in late 2026.

Eraring delivers up to a quarter of electricity supply in New South Wales. The 40-year-old plant is scheduled to close in August 2027, as part of an agreement with the NSW Government to support security of supply through the transition and while there remains uncertainty regarding the timing of transmission, renewables and firming infrastructure coming online.