Having chalked up three major solar power purchase agreements in as many months, EnergyAustralia is talking large-scale energy storage this week, in a briefing with the federal government on the potential for a massive pumped hydro project in the renewables rich state of South Australia.

EnergyAustralia managing director Catherine Tanna, along with the company’s executive for energy, Mark Collette, were in Sydney on Tuesday updating the Cabinet Energy Committee on the progress they have made, along with their research partners Melbourne Energy Institute and Arup Group, investigating the viability of a pumped hydro energy storage plant using seawater.

In a statement on Tuesday, Arup Group said that the proposed South Australia project would have the capacity to produce around 100MW of electricity with six-to-eight hours of storage – the equivalent of 60,000 home battery systems, EnergyAustralia says, but at “one-third of the cost.”

Pumped hydro, one of the oldest and most basic and low-cost forms of energy storage, converts electrical energy into potential energy by pumping water up to the top of a hill, storing it there in a reservoir, and then using it when needed to generate electricity at very high efficiency.

Most recently in Australia, it has been linked with a ground-breaking project being developed by Genex Power, which proposes to convert an old gold mine into a 330MWh pumped hydro storage project, to go alongside a 150MW solar PV array.

But its potential for Australia has come into sharper focus in recent months, as governments and electricity market operators grapple with the problem of how to support the smooth transition of electricity networks to renewable energy generation.

In Western Australia, for example, where a state election looms, the front-running Opposition Labor party has pledged to “revitalise” the state’s coal towns, such as of Collie, with new solar, biomass and pumped hydro facilities.

And last November, ARENA announced the provision of $449,000 in funding for the Australian National University to map potential short-term off-river pumped hydro energy storage sites around Australia.

Federally, the PM has also called for further investigation into what role “pumped hydro” could play in improving energy stability in Australia, telling the National Press Club last month that he had asked Chief Scientist Alan Finkel to report back on the subject.

The EnergyAustralia consortium’s project is proposed for the northern end of the Spencer Gulf, on a site with 300 metres of elevation, within 2km of the coast and close to high voltage transmission lines.

The Melbourne Energy Institute’s Roger Darville has described the site as “ideal” for pumped hydro with seawater in South Australia.

“Pumped hydro storage using seawater is just one of the innovations we’re looking at to increase Australia’s supplies of cleaner energy,” Tanna will tell the Energy Committee on Tuesday.

“The technology works like a giant battery. Its great advantage lies in complementing the shift to renewable energy by providing a reliable store of affordable power.

“On hot days, when demand spikes, a pumped hydro plant can be brought into action in minutes, keeping the lights on and costs down. We’re really excited by its potential,” she said.

But the use of seawater, as is proposed for the South Australia project, is a fairly new twist on the technology, as Arup’s strategy and policy lead advisor, Stephen Thompson, has noted.

“(This) would not only be the second example of a seawater pumped hydro storage plant anywhere is the world; it would also be the largest,” Thompson said.

Nevertheless, EnergyAustralia and co. are aiming to have a feasibility study done by mid-2017, and – If the project is deemed viable – the team say the project could be providing peak power to the grid by the summer of 2020/21.