Greek developer Metlen Energy and Metals, formerly known as Mytilineos, has submitted a 4.8GWh battery energy storage system (BESS) for approval under the Australian government’s Environment Protection and Biodiversity Conservation (EPBC) Act.
If approved, the 2.4GW 2-hour duration Denman BESS would be one of the largest battery storage projects in Australia, eclipsing the likes of Origin Energy’s 2.8GWh Eraring BESS in New South Wales, and the State Electricity Commission’s (SEC), an entity-owned by the Victoria government, 1.6GWh Melbourne Renewable Energy Hub.
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The proposal, which is available on the EPBC Act portal, includes developing the BESS alongside the associated infrastructure. This includes operation and maintenance buildings, internal access tracks, civil works, and electrical infrastructure and substations.
The Denman BESS will connect to the grid via a 500kV transmission line near the site.
The proposed BESS is located 7.7km northeast of Denman and 16.7km southwest of Muswellbrook in the New South Wales Upper Hunter region. The region is currently part of the Hunter-Central Coast Renewable Energy Zone (REZ).
Under the current timeline, the project’s determination is expected in October 2025, and construction will begin in 2026 or 2027. Construction is then expected to last around 28 months.
It should also be noted that the wider Denman Renewable Energy Hub, which the Denman BESS is a part of, also includes the development of a 90MW solar PV plant called the Upper Hunter South Solar Farm. It has been submitted to the EPBC Act as a separate proposal.
The project’s solar PV element timeline differs from the BESS, with construction starting in 2026. The proposal’s determination is expected in October 2025.
Interestingly, the Australian Financial Review reported last year that the developer had put up for sale an Australian energy storage and solar PV portfolio, including eight solar PV power plants and a 2.9GW development pipeline. The sale was being brokered by Macquarie.
Australia’s rise as the ‘multi-gigawatt proving ground’
The submission of the 4.8GWh BESS project strengthens claims made to Energy-Storage.news in December last year by Andy Tang, VP of Wärtsilä Energy Storage & Optimisation, who said Australia had become the multi-gigawatt proving ground for large-scale BESS projects.
“The projects in Australia are at a scale that is not seen anywhere else in the world,” Tang said when discussing the company’s involvement in the Eraring project.
Tang hopes the Eraring BESS can help showcase the feasibility of deploying multi-gigawatt-scale energy storage systems to the world.
“You have some desert projects in the US that occasionally hit the 1GWh range. But with Australia, between this project and some of the other announced projects that are going on, 1GWh almost seems like the average size,” Tang explains.
“The Eraring project, at over 2GWh, is massive globally. It’s about proving that these things can be done at scale. I think that’s important.”
Like many developers worldwide, Tang explains that Australia has become a key focus market for Wärtsilä, with the company having dedicated “significant resources” to the country.
“Australia has been one of our target markets for our energy storage business. We have essentially seven target markets, the US and certain European markets, like the United Kingdom, Belgium, Netherlands, Italy, and the APEC region,” Tang explains.
“Australia, Taiwan and the Philippines are big focuses for us, but Australia is just about our single largest market. We have dedicated significant resources to the market. I think you’ll see more good things coming from us, out of the Australian market, on the BESS side.”
Our publisher Solar Media will be hosting the Energy Storage Summit Australia 2025 in Sydney from 18-19 March. You can get 20% off your ticket by following the link here.
