Huge 4 gigawatt hour battery – Australia’s biggest – seeks approval to soak up solar north of Sydney

A huge four-hour battery sized at 4,000 megawatt hours – much bigger than any other big battery currently operating or under construction in Australia – has been proposed for a site north of Sydney, where its proponents say it will be ideally positioned to soak up excess solar power.

The Kiar battery – 1,000 MW and 4,000 MWh (4 GWh) – is being proposed by Australian developers Bid Energy next to a coal mine on the main 330 kV transmission line running between Sydney and the soon-to-retire coal fired power generators on the central coast.

It will be significantly bigger than the 700 MW, 2,800 MWh Eraring battery now being built at the site of the country’s biggest coal generator, and Bid Energy says its battery will help support the renewables being built to replace that coal fired generator and others that are soon to retire, including Vales Point.

“The Kiar site has been chosen because of some very favourable characteristic on the transmission system in that area, particularly as coal plants are eventually retired and the capacity from the proposed Renewable Energy Zones and the Hunter Transmission Line come on line,” Bid Energy director Ben Bolot told Renew Economy.

“There is definitely a time imperative in moving projects forward as quickly as possible. There are risks to the system generally in new storage and generation projects being delivered in time and delays in the approval and connection process could result in potential gaps in the market.

“Our experience to date has been that the NSW Government has been very responsive and supportive of moving projects through the approvals process quickly while managing the environmental and social impacts of project development.”

Big number of big batteries on the way

Kiar is just one of a swathe of very significant battery energy storage systems (BESS) lining up to replace these coal generators.

Just 10km to the north-east is the Waratah super battery, Australia’s current most powerful storage site at 850 MW, 1680 MWh which is going through commissioning now, and is acting as a kind of giant shock absorber for the grid. Origin Energy’s more conventional Eraring battery is about 15km to the north.

The Kiar project has just been sent into the federal environmental approvals process and is at the very start of the NSW planning journey.

Potential battery curtailment caused by clusters of storage projects is a issue now beginning to pop up as a talking point at conferences.

Bolot says this is a risk for the future, but is confident that over time business models will adapt.

“There are a range of other projects that are proposed for the general region but we are of the view that over time asset owners will manage storage and discharge to optimise returns and limit network constraints,” he says.

“However, this is an emerging risk for the market which will require new and adaptive thinking to manage the risk.” 

Another solar soaker

Bid Energy hopes to start construction in 2026 and begin operations from late 2027, around the time that Eraring may close, although it does have an option to keep operating until early 2029, depending on market conditions.

“The entire coal generation fleet in the National Electricity Market (NEM), which is currently providing the ‘firming” to intermittent VRE generators, is forecast to retire before 2040,” Bid Energy Partners said in its scoping report for the Kiar battery.

“BESS assets like the Project are essential to the future operation of the electricity grid, as they provide the ability to ‘firm’ intermittent VRE generators and store this energy for later flexible dispatch to the grid at the time it is required by energy users.”

Bid Energy says the battery will be primarily focused on soaking up excess solar in the middle of the day.

“The primary purpose … is to store energy during periods of surplus electricity generation in the electricity network, typically excess solar renewable generation in the middle of the day and then return that stored energy to the electrical network during periods of high demand, typically the afternoon and morning peak demand periods.

“Additionally, the Project will provide market ancillary services such as frequency control and key electricity network services that support the secure and reliable operation of the electricity network for the benefits of consumers and businesses.”

The developer is investigating a 110 hectare area for an approximately 40 hectare site that will include the battery, the cut in to the Transgrid transmission line which goes through the site, and access road.

It will need to avoid sections which are flood prone, and others which are prone to subsidence thanks to the site being right next to a coal mine owned by Wyong Coal – its only direct neighbour.

• *This article has been updated with comments from Bid Energy Partners director Ben Bolot.
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