Eight-hour battery approved in Western Australia, where capacity pay starts at six
Serguey Asael Shinder2 min readMint Renewables has received planning approval for a battery energy storage system near Kojonup, in Western Australia's Great Southern region, Energy-Storage.news reported on 9 October. The Regional Development Assessment Panel approved the development application.
The project in numbers. Documents lodged with the shire in May describe a 100 MW system with eight hours of duration — 800 MWh. The site lies about 3 km north-west of Kojonup and 241 km south-east of Perth, covering about 34.5 hectares, of which about 8.1 hectares would be disturbed, mostly cleared farmland. It adjoins the existing Kojonup substation; an on-site substation would step up from 33 kV to 132 kV, with underground cabling to the existing one. Western Power, the network owner, is still working with Mint on the connection, and the route stays indicative until detailed design.
Timeline. Construction is expected to take about 55 weeks, starting in the fourth quarter of 2027 at the earliest, with commissioning around 2029 — both subject to approvals and other dependencies. The application estimates up to 110 construction jobs, averaging about 37. The site is in a designated bushfire-prone area, and the application includes a bushfire management plan.
Why eight hours. Western Australia's main grid, the South West Interconnected System, is not part of the eastern states' National Electricity Market. It runs its own Wholesale Electricity Market, operated by AEMO, and that market's Reserve Capacity Mechanism pays for capacity that can be called on at demand peaks — but a battery qualifies only with at least six hours of duration. That rule is reshaping projects in the state: two-hour and four-hour designs common in the east earn no capacity payments here. An eight-hour system clears the threshold with margin, at the cost of buying twice as many cells per megawatt as a four-hour battery.
The developer. Mint is an Australian developer of solar, wind and storage. Its 200 MW / 400 MWh Dederang battery in north-east Victoria was fast-tracked by the state government in 2025 over the local council's opposition, at a cost put at about AU$280 million in planning documents. In New South Wales it has referred Magpie Hill, up to 375 MW of solar paired with a 375 MW / 3,000 MWh battery, to the federal environmental assessment process, with construction targeted for mid-2028.
Approval is a planning step only: the project still needs a grid connection agreement and a final investment decision.
Source: Energy-Storage.news, 9 October 2026 — https://www.energy-storage.news/mint-renewables-wins-planning-approval-for-800mwh-battery-storage-system-in-western-australia