New research from the University of NSW outlines how agricultural water reservoirs could be converted to small-scale hydro energy storage sites to support the uptake of renewable power systems in Australian rural communities.
The study suggests agricultural reservoirs, such as those used for solar-power irrigation, could be connected to form micro-pumped hydro energy storage systems – household-size versions of the Snowy Hydro hydroelectric dam project.
The UNSW study is the first in the world to explore the potential of these small-scale systems as an innovative renewable energy storage solution.
“The transition to low-carbon power systems such as 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.
“We thought, if you’re geographically fortunate to have two significant water volumes separated with sufficient elevation, you might have the potential for a hydro energy storage system.”
In a micro-pumped hydro energy storage system, excess solar energy from high production periods is stored by pumping water to a high-lying reservoir, which is released back to a low-lying reservoir when more power is needed, flowing through a turbine-connected generator to create electricity.
For the study, the UNSW team joined forces with researchers from Deakin University in Melbourne and the University of Technology Sydney. They used satellite imagery to create agricultural reservoir pairings across Australia from a 2021 dataset of farm dams, as well as graph-theory algorithms to filter commercially promising sites based on minimum capacity and slope.
“If you have a lot of dams in close proximity, it’s not viable to link them up in every combination,” says Dr Thomas Britz, co-author of the study and senior lecturer at UNSW Science’s School of Mathematics and Statistics. “We use these graph-theory algorithms to connect the best dam configurations with a reasonable energy capacity.”
From nearly 1.7 million Australian farm dams, researchers identified more than 30,000 sites as promising for micro-pumped hydro energy storage. It is estimated the average site could provide up to 2kW of power and 30kWh of usable energy – enough to back up a South Australian home for 40 hours.
“We identified tens of thousands of these potential sites where micro-pumped hydro energy storage systems could be installed without undertaking costly reservoir construction,” says Dr Gilmore.
“That’s thousands of households that could potentially increase their solar usage, saving money on their energy bills and reducing their carbon footprint.
“While the initial outlay for a micro-pumped hydro energy storage system is higher than a battery, the advantages are larger storage capacity and potential durability for decades.
“That cost is significantly reduced anyway by capitalising on existing reservoirs, which also has the benefit of less environmental impact.”
The use of micro-pumped hydro energy power systems with existing farm dams could provide rural areas that are susceptible to power outages with a reliable backup electricity source that is clean.
“People on the fringes of the electricity network can be more exposed to power outages and supply can be less reliable,” says Dr Gilmore.
“If there’s a power outage during a bushfire, a pumped-hydro system will provide enough energy to last a day whereas a battery typically lasts around eight hours.
“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.
“The next step will 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.”