'Gravity batteries' back future power grid

Some 1500 sites across Australia could be used for small-scale hydropower systems.

Researchers from the Australian National University have released a detailed study outlining the locations that could potentially be used to build pumped hydro energy storage (PHES) facilities.

The report includes possible options close to the nation's largest pumped hydro project, Snowy 2.0, and they don't need to dam a river.

The energy storage system works like a giant "gravity battery" and requires a pair of water reservoirs at different elevations as water is pumped from one reservoir to another.

The electricity generated during this process can be stored and used at a later time.

Researcher Anna Nadolny said the water and land needs are small, and improved energy efficiency and productivity would make them even smaller.

About three litres of water per day, per person is needed for the initial fill of the reservoirs and to replace evaporation - equivalent to about 20 seconds of a morning shower.

"About three square metres of land per person would be needed to form the required reservoirs, which is about the same size as a double bed," she said.

Energy expert Andrew Blakers said, if developed, the sites could be key to developing cost-effective, reliable, and 100 per cent renewable electricity grids.

The study follows the team's identification of 530,000 potential pumped hydro sites across the globe.

The energy storage system requires a pair of water reservoirs at different elevations as water is pumped from one reservoir to another. 

The electricity generated during this process can be stored and used at a later time.

"On sunny and windy days, water is pumped uphill from the lower to the upper reservoir," Prof Blakers said. 

"On calm days or at night, the water returns downhill from the upper to the lower reservoir to generate power."

He said this process can occur continuously for more than 50 years, making it a viable long-term storage solution to support solar and wind generated electricity.

It would also help Australia reach its target of achieving net zero greenhouse emissions, he said.

The ANU Bluefield PHES Atlas is designed to help accelerate Australia's adoption of renewable energy systems.

Hydro can be used to back up solar and wind farms to support new renewable energy zones and water supply dams could also host the technology.

Researcher Ryan Stocks said it's much cheaper than big batteries for prolonged periods of energy storage and can store electricity for several days or weeks.

Australia has about 300 times more storage potential than needed to support a 100 per cent renewable energy system, the research shows.

"We can afford to be choosy and only develop the very best sites," he said.

Options in the atlas range from two to 500 gigawatt-hours of energy storage, compared to the much larger Snowy 2.0 in NSW and Queensland's Kidston project currently under construction.

Snowy at full capacity will provide enough energy storage to power three million homes for a week.