Andrew Blakers, ANU

There are 5000 sites across the country suitable for pumped hydro storage, which could provide the stored energy needed for a 100 per cent renewable energy system.

The ANU plan, revealed in February, said a 100 per cent renewable grid of wind and solar backed up by pumped hydro would eliminate the need for gas and coal, and would be potentially cheaper than replacing old coal and gas plants with new gas.

Now the team behind the project say they’ve discovered 5000 potential sites for pumped hydro in Tasmania, Queensland, around Canberra and in Alice Springs.

ANU Professor Andrew Blakers said the sites had storage potential ranging from 0.9 gigawatt-hours to more than 100GWh, and could give current battery technology a run for its money.

“Each site has seven to 1000 times larger storage potential than the 0.13 GWh Tesla battery to be installed in South Australia,” Professor Blakers said.

“Additionally, pumped hydro has a lifetime of 50 years compared with eight to 15 years for batteries.”

Currently pumped hydro constitutes 97 per cent of the world’s energy storage market and has 159GW of deployment globally. So why hasn’t Australia gone down this route before?

“The simple reason is until you have 50, 60, 70 per cent renewables you don’t need storage,” Professor Blakers told The Fifth Estate.

He said South Australia was already at 50 per cent renewables and would need storage when it hit 60 per cent, which was only around three years away.

“So South Australia really needs to get its skates on.”

It is doing that in the form of the recently Tesla battery project, however Professor Blakers said the scale of the project paled in comparison to the potential of pumped hydro.

“Batteries can be put in quickly, but the Tesla project really is very small.

“If you want serious energy storage, you need pumped hydro. Batteries are useful for small projects or urban areas. They’re complementary.”

He said the scheme was similar and also highly complementary to the government’s proposed Snowy 2.0 scheme.

“All we’ve done is find all of the possible sites.”

How it works

Pumped hydro works by cycling water between a pair of reservoirs separated by at least 300 metres. When there is surplus energy, water is pumped up to the top reservoir, and released through a turbine to generate electricity in times of need.

Dr Matthew Stocks from the ANU Research School of Engineering said 3600 hectares of reservoir would be needed to support a 100 per cent renewable grid, which was just five parts per million of Australia’s total land mass.

Already the pumped hydro sites identified would provide energy storage potential of 15,000GWh, which is around 35 times that needed to support an entirely renewable energy system.

“Further site searching is underway in NSW, Victoria, Western Australia and the Northern Territory, and will add greatly to this total,” Professor Blakers said.

While Professor Blakers said the assessment was based on “very appealing physical characteristics”, he said upper reservoir sites would require due diligence on land ownership, environmental considerations, engineering and hydrological assessment – so many may turn out to be unsuitable, or too costly.

The report found that less than one per cent of the annual commercial water market would be needed to fill the reservoirs initially, and that because most good sites were located near the coast, expected rainfall would be more than evaporation loss if high quality evaporation suppressors were used.

“Whether or not evaporation suppressors were used would depend upon the cost of commercially supplied water or the availability of local water,” the report said.

A cost model is currently under development to allow optimisation of the pipe/tunnel route and lower reservoir site.

The project has received $449,000 from the Australian Renewable Energy Agency to develop a nationwide atlas of potential off-river pumped hydro storage sites.

“Storage is becoming more important and valuable as we move towards higher levels of renewable energy in our grids,” ARENA chief executive Frischknecht said.

“Pumped hydro is the most mature form of energy storage, and studies like these are helping to determine whether it could play an even greater role in increasing grid stability.”

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