Australia’s longest duration battery will come online this year, a major milestone as the power grid charges towards a mostly renewable energy future.
When fully charged, the Limondale battery in south-west New South Wales will be able to pump 50MW of power back into the grid over eight hours.
“Long-duration storage technologies, such as large-scale batteries and pumped hydro, are set to play a fundamental role in supporting Australia’s transition to clean energy,” says Veronika Nemes of the Clean Energy Council. This type of storage will be critical for grid stability and security, she says, as coal retires over the next decade.
But what is a long-duration battery, and why does it matter? And can it help with rare and unpredictable periods of renewable drought called “dunkelflaute”?
How does the Limondale battery work?
The eight-hour battery is next to the Limondale solar farm, near Balranald in the Murray region of NSW.
This week its 144 Tesla megapacks began grid testing, a moment its developer called a “major milestone in Australia’s energy transition”.
Last year the average duration for grid-scale batteries commissioned in Australia was 2.7 hours. The Limondale project, supported by a NSW tender for long-duration storage, achieves more hours with additional battery cells and a control system optimised for the task.
The project is designed to store excess renewable energy during the day and dispatch it in the evenings and mornings when demand is high.
Daniel Belton, the chief executive of RWE Renewables Australia, said projects like Limondale were “helping to unlock the full value of renewable generation by ensuring energy is available when it’s needed most”.
What is long-duration storage and why is it useful?
Grattan Institute’s Alison Reeve says while definitions vary, long-duration energy storage generally refers to technology that can dispatch eight or more hours’ worth of electricity.
It’s useful because as the amount of wind and solar in the grid grows the power system needs to manage that variability.
Reeve says there are two options: “One is to be cleverer about when you use the energy … make your demand match your supply pattern. But you also want the flexibility to be able to shift the supply to different times of the day, and that’s what storage does.”
Australia’s energy market operator anticipates a mix of what it calls shallow (up to four hours), medium (four to 12 hours) and deep storage (12+) will be needed as the nation’s share of wind and solar increases.
Shallow helps to manage daily fluctuations and frequency stability, while four- to 12-hour systems bank surplus wind and solar for use during morning and evening peaks.
What is ‘dunkelflaute’ and can we avoid it?
Seasonal, or deep storage (beyond 12 hours), is more like an insurance policy, a strategic reserve for managing rare but unpredictable periods when cloudy and still weather conditions persist over several days.
The phenomenon known as “dunkelflaute” (dark doldrums) is specific to highly renewable grids.
“That’s the bit that is hardest to solve,” Reeve says.
In Australia this risk is low and it can be minimised by the geographic spread of solar, wind and hydro generation, or managed with seasonal storage like pumped hydro, like Snowy 2.0.
What are the other energy advantages of eight-hour batteries?
“Storage economics is quite complex,” says Prof Bruce Mountain, the director of the Victorian Energy Policy Centre.
Mountain says different combinations of short- and long-term batteries can meet the needs of a highly renewable system. But as coal leaves the grid, creating longer periods of high prices in the evening, longer duration batteries become more attractive.
“What solar firmed with batteries offers is a certain energy resource,” he says. It can be dispatched on demand to meet higher prices, whereas wind only has a certain likelihood of being available.
The arrival of eight-hour batteries is significant, Reeve says, because they start to compete with pumped hydro.
Pumped hydro, which stores energy by pumping water uphill, is long and complex to construct and only possible in specific locations. In contrast, Reeve says, batteries are easy to deploy.
“It would mean we could move a bit faster with letting more renewables into the grid, because we’ve got less worries about reliability, if the storage is there.”
Nemes says strategic deployment of medium- to long-duration storage will “lower the total cost of grid infrastructure to be built, keeping the impact to consumer energy bills as low as possible”.
