Eku Energy has fully commissioned its 250MW/500MWh Williamsdale battery energy storage system (BESS) in the Australian Capital Territory (ACT), completing the ACT government’s Big Canberra Battery project.
The developer, co-owned by Macquarie Asset Management and Canadian pension investor British Columbia Investment Management Corporation (BCI), announced on Thursday (5 November) that the 2-hour BESS south of Canberra is in commercial operation, and said it was delivered on time and on budget.
ACT chief minister Andrew Barr attended a commissioning celebration alongside ACT Legislative Assembly members Caitlin Tough and Taimus Werner-Gibbings. Barr was also present when Eku broke ground on the project in November 2024, shortly after financial close.
The project uses Tesla Megapack 2 XL units, with Consolidated Power Projects as balance of plant contractor. Evoenergy acted as distribution network service provider, while the Australian Energy Market Operator (AEMO) supported the grid connection approval process.
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Each Megapack 2 XL enclosure integrates Tesla’s own inverters, so Tesla supplied the power conversion system (PCS) as well as the battery cells. Tesla has since begun production of its next-generation Megapack 3 in Texas.
“We’re delighted to have commissioned the Williamsdale BESS, which is now ready to provide energy security and support the ACT’s electricity needs for the long term,” said Tom Best, chief operating officer at Eku Energy. He thanked delivery partners “for their commitment over the past nearly two years”.
Under its contract with the ACT government, Eku receives fixed quarterly payments over 15 years for system strength and frequency control ancillary services (FCAS), while the territory takes a share of the BESS’s National Electricity Market (NEM) revenue through a revenue swap. The BESS was designed to run in grid-forming mode.
Eku also appointed Habitat Energy, part of Quinbrook Infrastructure Partners, to optimise the Williamsdale BESS in December 2024. Habitat said at the time it had around 2.8GW of assets under contract worldwide.
“The Williamsdale BESS marks the completion of the Big Canberra Battery project as the ACT moves towards electrifying our city and achieving net zero emissions by 2045,” Barr said. The ACT government pledged AU$100 million (US$70.4 million) to the Big Canberra Battery project in its 2020-21 budget.
Eku said it has distributed AU$500,000 to nine local organisations, including OzHarvest, YWCA Canberra and the St Vincent de Paul Society, through its Powering Big Dreams community benefit-sharing programme.
The company has provided a further AU$500,000 to the Australian National University’s (ANU) Centre for Energy Systems to study the role of utility-scale BESS. An ANU-led workshop helped shape the community co-designed Big Canberra Battery programme, according to Eku.
Eku Energy’s Australian pipeline
Williamsdale was one of three Eku projects in construction when CEO Daniel Burrows told ESN Premium in an interview in April that the company had developed 10 projects totalling 2.9GWh. Five were operating at the time, and two more were contracted.
One of those contracted projects is the Griffith BESS in New South Wales (NSW), expanded to 100MW/1,000MWh (10-hour) after it won a long-term energy service agreement (LTESA) in AEMO Services’ long-duration storage tender in February 2025.
Earlier this year, Eku referred two 300MW/1,200MWh BESS projects to the federal government under Australia’s EPBC Act: Tramway Road at Hazelwood North in Victoria and Wongalea near Armidale, NSW. Construction at Tramway Road could start in late 2026, with operation targeted for 2028.
Best said the NEM’s design had allowed new technologies to trade energy effectively, in an interview with ESN Premium on why the market design must evolve. “Merchant finance is challenging, but it’s a way to accelerate project delivery,” he said.
In January 2026, ENGIE acquired Eku’s 30% stake in the Hazelwood BESS in Victoria to take full ownership. Eku has also entered New Zealand by acquiring a BESS project in Waikato, working with local developer Helios Energy on planning.
Grid-forming capability, as at Williamsdale, features in around 74% of the 33.2GW NEM BESS pipeline, according to AEMO data.
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