Dam and water storage for the hydro scheme in the Snowy Mountains - but there are thousands more sites. "Fast tracking the development of a few of the best sites by 2022 could balance the grid when Liddell and other coal power stations close," he said, referring to the 1680-megawatt coal-fired power plant the federal government is trying to strong-arm AGL Energy to keep open five years beyond the 2022 scheduled close. "We found so many good potential sites that only the best 0.1 per cent will be needed," he said. "We can afford to be choosy." Interest in pumped hydro has increased in the wake of Prime Minister Malcolm Turnbull's much-publicised twin visits to the Snowy Hydro scheme since March. The so-called Snowy 2.0 project would potentially increase the generation capacity of the scheme by half, with a feasibility study now underway.

The ANU study, though, highlights the possibility of many alternative, smaller projects that could be completed sooner than the Snowy upgrade. Such ventures may also be less challenging than drilling many kilometres of tunnels under the Snowy region. "Instead of propping up dirty old coal-fired power stations like Liddell, Malcolm Turnbull should be investing in energy storage now," Adam Bandt, Greens spokesman for climate change and energy, said. "Snowy 2.0 is years away, but there are plenty of sites for smaller, flexible dispatchable pumped hydro that could be up and running in a couple of years if [he and energy minister] Josh Frydenberg showed some real leadership," Mr Bandt said. Of the other states to be revealed in the new report, Western Australia has about 3800 prospective pumped hydro locations, and the Northern Territory 1500. Queensland has about 1770 and Tasmania 2050 and South Australia 185. Fairfax Media sought comment from Mr Frydenberg's office, which declined to release the ANU report.

A spokesman pointed to comments made by the PM earlier this month, saying that keeping Liddell open for another five years would give time for Snowy 2.0 - with its proposed 2000 MW capacity - to come on line. Making 100 per cent possible With pumped storage, water is kept in an upper reservoir and run through a turbine at a lower altitude to provide electricity during periods when supplies are otherwise low. The water can later be pumped uphill from a lower reservoir when electricity supplies are in surplus. Typically, the height difference between upper and lower reservoirs measured for the prospective sites was at least 300 metres. "All the potential sites we have found are outside national parks and urban areas, and like all hydro power can go from zero to full power very quickly," Professor Blakers said in August when the initial study results were released.

That partial research, funded by the Australian Renewable Energy Agency, identified pumped storage sites with capacity ranging from 0.9 to 100 gigawatt-hours – or as much as 1000 times being proposed for a giant battery being built for South Australia by Tesla. At the time Professor Blakers said batteries also had the disadvantage of lifetime use of eight to 15 years at current technology, compared with 50 years for hydro plants. Pumped hydro is one of the possible technology solutions to firming up renewable energy for when the sun is not shining or the wind blowing. The Finkel Review identified the need to provide back-up capacity as one of the potential road blocks hindering much greater penetration of clean energy as a share of national electricity supplies. Loading

The extended atlas of sites will build on the partial study of the states to reinforce the view that Australia could shift to 100 per cent renewable if enough pumped storage is made available. "About 3600 hectares of reservoir is required to support a 100 per cent renewable energy grid for Australia, which is five parts per million of Australia's land mass," Matthew Stocks from the ANU Research School of Engineering said in August. "Annual water requirements would be less than one per cent of annual extraction from the Murray River."