Research from the University of New South Wales (UNSW) , Deakin University and UTS suggests that an abundance of small-scale hydro energy storage sites could be built from farm dams in regional areas, which would allow for a renewable energy uptake in rural communities.

Tens of thousands of the storage sites could be powered from agricultural reservoirs, each connected to form micro-pumped hydro energy storage systems. Likened to household-size versions of the Snowy Hydro hydroelectric dam project, the research is the first of its kind to outline the potential of small-scale hydro systems.

The increasing use of variable energy sources like wind and solar necessitates energy storage to maintain a stable power supply. The hydro energy storage stores excess energy by pumping water to a high reservoir and releasing it to a low one when needed, generating electricity. However, building new reservoirs for this can be costly.

“The transition to low-carbon power systems like wind and solar photovoltaics needs cost-effective energy storage solutions at all scales,” says Dr Nicholas Gilmore, lead author of the study and lecturer at the School of Mechanical and Manufacturing Engineering at UNSW Engineering.

“We thought – if you’re geographically fortunate to have two significant water volumes separated with sufficient elevation, you might have the potential to have your own hydro energy storage system.”

A 2021 dataset of farm dams enabled the research team to pair similar reservoirs across the nation with one another. Graph theory algorithms, which models how nodes can be connected, filtered the sites based on minimum capacity and slope.

30,000 sites across Australia were then earmarked as potential energy storage systems, with an average of 2 kW of power and 30 kWh of usable energy generated – enough to back up a South Australian home for 40 hours. Thousands of households could then increase their solar usage, reducing emissions and cutting energy costs.

“If you have a lot of dams in close proximity, it’s not viable to link them up in every combination,” says Co-Author and UNSW Senior Lecturer Thomas Britz.

“So, we use these graph theory algorithms to connect the best dam configurations with a reasonable energy capacity.”

Compared to a commercially available lithium-ion battery in solar-powered irrigation systems, the hydro storage is a third cheaper for a large single cycle load due to its high storage capacity. The mini hydro systems could also assist rural areas susceptible to power outages.

“People on the fringes of the electricity network can be more exposed to power outages, and the supply can be less reliable,” Gilmore continues.

“If there’s a power outage during a bushfire, for example, a pumped hydro system will give you enough energy to last a day, whereas a battery typically lasts around eight hours.”

Gilmore says that the study did not cover all bases, with further analysis regarding fluctuations in water availability, pump scheduling and discharge efficiency required.

“Our findings are encouraging for further development of this emerging technology, and there is plenty of scope for future technological improvements that will make these systems increasingly cheaper over time,” he says.

“The next step would be setting up a pilot site, testing the performance of a system in action and modelling it in detail to get real-world validation – we have 30,000 potential candidates!”

To read the study in full, click here.

Jarrod Reedie

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