Origin Energy has dusted off decade-old plans to build one of the biggest peaking power plants in Australia, in the Southern Tablelands region of New South Wales, and made it even bigger.
Origin is the country’s biggest energy retailer, the owner of the biggest coal generator, and already the biggest operator of gas fired generation in the country.
Now it wants to boost that gas portfolio with the construction of the 1.2 gigawatt Kerrawary gas fired generator, about 40 kms north of Goulburn. It’s a reprise of a project once called Big Hill and which originally envisaged a 1 gigawatt installation, but is now being expanded.
Kerrawary is one of two massive gas fired power stations proposed for the region, with rival utility EnergyAustralia recently filing plans for the 1.4 GW Marulan facility, just a few kilometres away. Marulan is another project that was dusted off from a previous plan – it was originally put forward nearly 20 years ago, when it was half the size.
The Marulan project would be the biggest gas generator in the country once built.
Both the Kerrawary and the Marulan projects are drawn to the existing transmission line, and the plan to upgrade it, as well as the location of nearby substations. The gas generators are being justified by the need for “firm” power as the state’s grid transitions from majority coal to mostly wind and solar.
The region has already become a hot spot for other firming technologies, including a raft of big battery projects such as Bannaby and the even bigger 1,200 MW and 4,800 MWh Hanworth battery.
Origin says it has considered other technologies, but a proposed expansion of its Shoalhaven pumped hydro facility was not economic, lithium batteries were suitable for storage up to eight hours, and other technologies – such as flow batteries and compressed air storage – were considered too early in their development and too risky.
The Kerrawary project would be cited on land owned by Origin Energy and currently used for cattle grazing, but would also require a 35 km gas pipeline to connect into the main Moomba, and upgrades to roads, including a new bridge over the Wollondilly River.
Origin Energy says that the peaking plant would have a capacity factor of around 15 per cent, which sounds high for such facilities that often run at around 1 or 2 per cent capacity. Snowy Hydro’s recently completed Hunter gas project, for instance, expects a capacity factor of just 2 per cent.
Like Hunter, Kerrawary will mostly burn fossil gas, but may also run up to 200 hours a year on diesel, and will have a 10 million litre diesel storage facility on site, enough to power the generator for 40 hours at full capacity, according to a scoping report filed with the state government.
“Origin continues to invest significantly in renewable generation and storage assets, including the Eraring Battery, Mortlake Battery and Yanco Delta Wind Farm project, while also exploring opportunities for additional gas peaking capacity to support the energy transition,” the company says in the scoping report.
Origin had been scheduled to close the 2.88 Eraring coal generator in NSW in 2025, but this has been delayed twice, first to 2027 and then to 2029 – and some fear it may be extended again due to the lack of replacement capacity.
Since announcing the “early” closure of Eraring 2022, Origin has not built any new wind or solar facilities. Like other big utilities is has focused almost entirely on big battery projects. There is only one wind farm currently under construction in NSW.
The Kerrawary project, subject to approvals, is expected to start construction in 2029 and be operational in 2033. The company held information sessions with community groups in July this year.
