Renewable energy storage solution in the air?

Australia’s first renewable energy storage facility using compressed air is on track to be developed in a disused Broken Hill mine in outback New South Wales.

The $652 million Silver City Energy Storage Centre, to be built in a decommissioned mine at Broken Hill, will use Advanced Compressed Air Energy Storage (A-CAES) technology developed by Canadian energy storage developer Hydrostor Inc.

The proposed centre is being touted as “a vast battery”, and an innovative solution to renewable energy storage.

The Australian Renewable Energy Agency (ARENA) announced in October (this month) it has conditionally approved $45 million in grant funding towards the project.

“Whether it be through pumped hydro, or new innovative solutions like compressed air storage, medium and long-duration storage is going to be vital to supplying power during the evening and morning peak-demand periods as Australia looks towards achieving 82 per cent renewable energy by 2030,” ARENA CEO Darren Miller says.

“Hydrostor’s innovative solution provides us with another option to add to the mix.

“As a fuel-free storage technology, compressed air storage technology has similar applications to pumped hydro, such as providing dispatchability to ensure reliability of the power system as more solar and wind power is installed.”

ARENA’s funding is conditional on the project proving financial viability, which is expected to happen in late 2023.

The Silver City Energy Storage Project would provide back-up power supply to Broken Hill’s remote off-grid community of about 16,000 people.

Hydroster says it is working with Energy Estate to build a 200MW facility with close to zero emissions. It will be among the biggest compressed air projects in the world.

The project will be capable of storing enough energy to power up to 200,000 homes over eight hours of peak demand.

“Over the 50+ year lifetime of Silver City, more than 11 million metric tons of carbon dioxide will be displaced which is equivalent to annual emissions of roughly 50,000 cars,” Hydroster states.

So how does the technology work?

Hydroster 002. Jpg
An ARENA graphic explains the process of Advanced Compressed Air Energy Storage.

ARENA describes A-CAES as “a kind of Alice Through The Looking Glass version of pumped hydro”.

While pumped hydro pumps water upwards, A-CAES uses excess energy or energy from a renewable source to compress air down into purpose-built subterranean tanks. A vertical column of water puts enormous pressure on the air tanks at the bottom.

When demand is high or energy prices are high, the system can release the compressed air upwards to power turbines and create energy. 

The scale of the renewable energy storage problem: Alan Finkel

“But Hydrostor’s system has one extra trick,” ARENA says in its announcement of the grant. “It captures and stores heat created when the air is first compressed.

“The system uses that heat energy to supercharge the released air’s energy content just before it hits the generator turbines.

“And that means, aside from the off-peak electricity to run the compressors, the system is fuel-free and therefore zero emission.”

A 16km transmission line will connect the facility to the Transgrid substation at Broken Hill.

Climate Change and Energy Minister Chris Bowen says the project would be Australia’s largest medium duration storage project, besides pumped hydro.

“New technologies for medium duration storage like Hydrostor’s technology can provide cheaper energy storage that can help move the nation’s electricity grid to 82% renewables by 2030,” Bowen says.

“The private sector has never been keener to invest in innovative projects crucial for Australia’s energy transformation, and we’re delivering the policy certainty and investment support to ensure these projects come forward.

“The cheapest form of energy by a country mile is renewable energy, backed by transmission and storage, and we’re making sure ARENA’s funding enables Australians to grasp this opportunity.”

To find out more about the technology, visit

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