Compressed air energy storage in an old zinc mine

Hydrostor Australia, a subsidiary of Advanced Compressed Air Energy Storage (A-CAES) company Hydrostor, has been awarded $6 million from the Australian Renewable Energy Agency (ARENA) and $3 million from South Australia’s Renewable Technology Fund for what is claimed to be Australia’s first energy storage project using compressed air.

The 5 MW/10 MWh fuel-free A-CAES facility, to be constructed by Hydrostor, will repurpose the Angas Zinc Mine in Strathalbyn, located 60 km southeast of Adelaide and currently in care and maintenance. The existing mine will be utilised to develop a below-ground air-storage cavern that uses an innovative design to achieve emissions-free energy storage. This will help to increase renewable energy supply to the South Australian and national energy grid while also converting a brownfield site into a clean energy hub.

A-CAES works by using electricity from the grid to run a compressor, producing heated compressed air. Heat is extracted from the air stream and stored inside a thermal store preserving the energy for use later in the cycle. The compressed air is then stored in a purpose-built underground cavern, which is kept at a constant pressure using hydrostatic head from a water column. During charging, compressed air displaces water out of the cavern up a water column to a surface reservoir, and during discharge water flows back into the cavern forcing air to the surface under pressure where it is reheated using the stored heat and then expanded through a turbine to generate electricity on demand.

The $30 million commercial demonstration project will be dispatched into the National Electricity Market (NEM) to provide synchronous inertia, load shifting and frequency regulation, and support grid security. Notably, it can provide the dispatchability required to ensure reliability of the power system as variable renewable energy resources, such as solar and wind, are installed.

The emission-free solution can be flexibly located where required on the grid, is deployable at both greenfield and brownfield sites, and offers an alternative to geographically constrained bulk energy storage technologies such as pumped hydro. As noted by ARENA CEO Darren Miller, “Compressed air storage has the potential to provide similar benefits to pumped hydro energy storage; however, it has the added benefits of being flexible with location and topography, such as utilising a cavern already created at a disused mine site.”

The successful deployment of A-CAES at the Angas Zinc Mine will open up opportunities throughout Australia for the build-out of full-scale (50+ MW), long duration (4–24+ hours), long-life (50+ years) projects, adding clean energy capacity and boosting reliability of power supplies across the NEM. Hydrostor is currently advancing several full-scale projects in Australia and working to identify additional sites for A-CAES deployment across the country.

“Hydrostor is very appreciative of the contributions from ARENA and the Government of South Australia for its first Australian A-CAES project,” said Hydrostor CEO Curtis VanWalleghem.

“We’re excited to have the opportunity to demonstrate the significant benefits of adding our flexibly sited, low-cost, bulk energy storage to the diverse range of technology helping Australia transition to a lower-cost, high system strength, cleaner electricity grid.”

Image credit: ©Mishainik/Dollar Photo Club

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