South Australia is on track to become one of the world's leading renewable energy systems, but new Adelaide University research shows that running the grid on 100 per cent renewable electricity at every moment could require far more storage than many estimates suggest.
The study, published in Energy, examined how much storage South Australia would need if the state had to meet demand using renewable generation and storage alone.
The modelling factored in rare but plausible periods of low wind and solar output, and times when support from the rest of the National Electricity Market was limited.
Lead author Harrison Payne, School of Electrical and Mechanical Engineering, said the findings highlight an important difference between producing enough renewable energy over a year and supplying electricity reliably at every minute of every day.
“South Australia has made extraordinary progress, with renewable generation growing from one per cent to more than 70 per cent in the past two decades,” Mr Payne said.
“But a real 100 per cent renewable grid is a much harder problem to solve than reaching net 100 per cent over a year. The system needs to keep the lights on through winter, during solar and wind droughts, and throughout periods of limited interstate support.”
Using AEMO’s forecast data for 2045 to 2051, the team developed a detailed multi-nodal model of the South Australian transmission network.
Unlike simpler studies that treat the state as one large electrical zone, the model captures where demand occurs, where renewable generation is located, how power flows through the network, and the losses and constraints affecting transmission flows.
Across all analyses, the study found South Australia would require a median of 4.27 GigaWatts and 162 GigaWatt hours of storage.
Under the most challenging weather year in the base case, the requirement rose to 7.28 GW and 644 GWh. By comparison, AEMO reported South Australia's operational grid-scale battery storage capacity at about 0.812 GWh in the first quarter of 2026.
“The scale is significant, but the key message is not that renewable energy cannot work,” senior author Dr Pourmousavi Kani, School of Electrical and Mechanical Engineering said.
“The key message is that the last few per cent of reliability are the hardest and need to be planned for carefully.”
Weather was one of the biggest drivers. Winter periods consistently set the storage requirement as lower renewable generation can coincide with higher demand over extended periods.
The research also found that storage requirements can fall sharply if a small amount of dispatchable generation is available during the most difficult periods.
Allowing dispatchable generation to meet just one to three per cent of annual demand reduced storage needs by up to 78 per cent.
“This shows the value of thinking about the whole system, not just the number of batteries,” Dr Pourmousavi Kani, the project lead, said.
“A small amount of firm backup, used rarely, can avoid a very large amount of overbuilding in storage.”
Mr Payne completed much of the work as an Engineering Honours student at Adelaide University, with the study developed through university and industry collaboration.
“These findings provide policymakers and planners a clearer framework for testing assumptions about storage, transmission, weather risks, and reliability as South Australia moves towards a high-renewable future,” Mr Payne said.