With the enormous uptake of rooftop solar, our energy market has become peakier – large amounts of power is generated during the day, when there is relatively low demand. As people begin to arrive home from work and school, demand rises – as the sun is going down.

In this context, peaking or flexible power supply, like the energy that would be generated from pumped hydro, has an extremely important role to play as it can be switched on to bolster energy supply when it’s needed.

How does pumped hydro work?

Excess energy produced during the day is used to pump large volumes of water to a geographically high point; then, when demand rises, the water is released back to the lower point – spinning turbines along the way to generate electricity. In this way, excess power can be stored.

How does pumped hydro work?
Kanmantoo pumped hydro

AGL has secured the right to develop and operate a 250 MW pumped hydro system at Hillgrove Resources’ Kanmantoo ex-copper mine in South Australia’s Adelaide Hills region.

A project of this size and scope has naturally raised many questions – some concerned, but many just interested in how this project will work. We have taken the most frequently asked and answered them below.

Pumped hydro FAQs

What is the storage capacity?

Hillgrove Resources have taken enough material out of the pit to store roughly 20GL of water. That’s about 8000 times the volume of an Olympic swimming pool – or 1/25 the volume of Sydney Harbour.

Where will storage be located?

We are currently assessing three options that involve building storage reservoirs north-west of the existing pit. These locations have been identified in order to use the natural geography of the area.

Where does the water come from?

Currently, Hillgrove Resources use a combination of Murray River water and recycled water from Mount Barker District Council. We are currently exploring the best way to source the water.

Is the water being drawn up from the aquifer below?

No water is being drawn up from the aquifer to fill the pit.

How much of an issue is evaporation?

Evaporation is definitely an issue. It will also be considered during the design process. We’ve calculated that we will need to top-up the scheme with about half a gigalitre each year once operational.

Will the pit be lined to reduce seepage back into the earth walls?

We won’t be lining the pit as it is mined into very solid, very ‘tight’ rock. In fact, the mining that is currently being undertaken now is below sea level – and there is almost no pumping occurring in the pit.

Will there be a dedicated solar / battery farm installed to pump water from the pit?

No, currently there are no plans to develop renewables or other storage projects on the site.


What pumped hydro projects are being considered?

On 7 February 2019, AGL announced it has secured an option over a 250 MW pumped hydro energy storage project at Bells Mountain in NSW, located 11km North of the Liddell Power Station.

On 16 April 2019, AGL announced it had secured the right to develop, own and operate a 250-megawatt pumped hydro energy storage project at Hillgrove Resources Limited’s Kanmantoo copper mine in South Australia’s Adelaide Hills region.

Read more about AGL’s generation portfolio in our interactive asset map.

Update: in February 2020, AGL and Hillgrove Resources Limited, which owns the Kanmantoo site, mutually agreed to not continue with the proposed pumped hydro project. However, AGL remains committed to continuing the development of energy storage projects such as batteries and pumped hydro to providing firming capacity to the market.

These projects include a 100 MW battery in Wandoan, Queensland, a 30 MW battery in South Australia, and four 50 MW batteries to be built in NSW. We are also investigating the feasibility of a 250 MW pumped hydro plant at Bells Mountain in NSW, and a 50 MW battery at Broken Hill.