Two Australian batteries holding 1.8 GWh entered AEMO's system on one day
Victoria Shinder2 min readTwo large batteries entered the Australian Energy Market Operator's Market Management System on 15 September 2026: Vena Energy's Tailem Bend BESS 3 in South Australia, known in the system as TB3B1, and the Wooreen BESS in Victoria, owned by EnergyAustralia and Banpu Energy Australia, registered as WOORB1. The registrations were noted by Geoff Eldridge of GPE NEMLog, who tracks project data across the National Electricity Market.
The registered parameters are the substance of the story. Tailem Bend BESS 3 carries an operating maximum of 204 MW, a registered capacity of 263 MW, 408 MWh of storage — a two-hour duration — and a ramp rate of 82 MW per minute. Wooreen is registered at 350 MW operating maximum, 491 MW registered capacity, 1,400 MWh over four hours, and 140 MW per minute. Taken together the two hold 1,808 MWh, which is our own addition of the two published figures.
Eldridge's caveat travels with the numbers: entering the MMS is not commercial operation. It is the step that lets a unit begin testing and commissioning before normal market participation.
Around the assets, the context is replacement capacity. Tailem Bend BESS 3 sits about 89 km east-south-east of Adelaide and connects through ElectraNet's Tailem Bend substation, alongside two existing Vena Energy assets; construction of the standalone project began in December 2025 with commissioning scheduled for 2027. Wooreen is at Hazelwood North in the Latrobe Valley, roughly 138 km from Melbourne, next to EnergyAustralia's Jeeralang power station; it reached financial close in February 2025 and is meant to be in service before the 1,450 MW Yallourn coal plant retires in mid-2028. EnergyAustralia sold half the project to Banpu in July 2025 in a deal put at around AU$700 million. Wärtsilä supplies the hardware, engineering and commissioning under a 15-year service agreement.
What it means
Registration dates are the honest leading indicator, and they are public. Announcements come at financial close, at groundbreaking and at "commercial operation", none of which is easy to check. A unit appearing in the market operator's own system with a registered capacity and a ramp rate is a fact with a date on it, and it sits roughly a season ahead of the revenue.
Four hours next to a retiring coal plant is a deliberate specification. Wooreen's 1,400 MWh over four hours is sized for the evening ramp that Yallourn currently covers, and its in-service target is set against the plant's retirement rather than against a market opportunity. The two-hour Tailem Bend unit answers a different question in a state already around 75% wind and solar.
Ramp rate is the number that will matter for frequency services. 82 and 140 MW per minute are the figures that decide what these assets can sell besides energy, and they are in the registration rather than in the press release.
⚠ Single trade source relaying a third party's reading of AEMO registrations; the arithmetic adding the two storage figures is ours.