As Australia heads toward an all-electric future, there’s growing concern about whether our electricity grid can handle the surge in demand from the widespread uptake of electric vehicles, reverse-cycle heating and cooling, electric stoves and hot water heat pumps.
But new modelling by researchers at the Australian National University suggests the key challenge is not the total amount of energy we’ll use, but when we use it.
The study, led by Dr Bjorn Sturmberg, and using the ACT as a case study, shows that there’s already significant spare capacity in the distribution network — the local “poles and wires” that deliver power to our homes.
This infrastructure is currently underutilised for parts of the day and year, so if we shift electricity use into those low-demand periods – when solar energy is plentiful and network demand is lower – we could electrify our homes and transport without overloading the system or building costly new infrastructure.
“Our electricity system as a whole is built for peak [demand] periods… and then for the rest of the day, for the rest of the year, the network is quite underutilised. It has spare capacity,” Sturmberg told the SwitchedOn Australia podcast.
The ANU team calculated the daily energy that will be needed to charge every electric vehicle and heat water in every home across the ACT in the future.
They then examined how the electricity distribution network is typically loaded. Winter evenings show the highest peaks — when households are heating and using appliances — but demand falls significantly during the day and late at night.
“The spare capacity during the daytime is only going to grow as more and more people install rooftop solar,” said Sturmberg.
By shifting power-hungry activities like water heating and EV charging into these underused hours, the researchers found the grid could absorb the extra load without exceeding its peak capacity.
“We actually found that all of the ACT vehicles charging and all of the water heating could be accommodated into those periods of underutilisation or of spare capacity in the distribution network,” he said.
The stakes are high. Electrifying transport alone could increase electricity demand in the ACT by around 45%, with the impact falling most heavily on zone substations in outer suburbs.
At the household level, even modest driving habits make a difference. The researchers estimate a single electric vehicle driving an average Australian distance of 30 kilometres a day will add in the order of 25% to households’ electricity consumption.
“So it’s a really material addition.”
However, it’s not the daily or the annual consumption of electricity that will pose the biggest challenge to the electricity system.
“It’s really the rate of which that electricity might be consumed,” said Sturmberg. “What we’re really focused on is peak demand.”
“If we all go home, plug our electric vehicles in at 6pm then that creates a huge spike in electricity demand… And if we have to build our whole electricity system, including the distribution network, to service that peak, that’s going to be very, very expensive.”
The cost implications are already baked into our electricity bills. The distribution network makes up about 30–40% of electricity bills.
“It’s a really significant part, and it’s a part that’s difficult for customers to do much about.”
Roughly half of those network costs goes towards paying off infrastructure that’s already been built: “Those are sunk costs that need to be paid back, and they get paid back over decades,” said Sturmberg.
The ANU research supports growing calls to prioritise using our existing grid more effectively before rushing to expand it. As Clare Savage, Chair of the Australian Energy Regulator, said last year: “We’re calling for a renewed focus on network utilisation and improved efficiency – for industry to look for ways to more effectively use the existing network before investing in new assets.”
Sturmberg argues that smarter scheduling of electricity use, particularly EV charging and water heating, is the key to making the most of infrastructure Australians are already paying for.
“We don’t want to be building infrastructure that we won’t actually need.”
Anne Delaney is the host of the SwitchedOn podcast and our Electrification Editor, She has had a successful career in journalism (the ABC and SBS), as a documentary film maker, and as an artist and sculptor.
