Source:
29 April 2025
The global energy system may be faced with an inescapable trade-off between urgently addressing climate change versus avoiding an energy shortfall, according to a new energy scenario tool developed by University of South Australia researchers and published in the open access journal Energies.
The Global Renewable Energy and Sectoral Electrification model, dubbed ‘GREaSE’, has been developed by UniSA Associate Professor James Hopeward with three civil engineering graduates.
‘In essence, it’s an exploratory tool, designed to be simple and easy for anyone to use, to test what-if scenarios that aren’t covered by conventional energy and climate models,’ Assoc Prof Hopeward says.
Three Honours students – Shannon O’Connor, Richard Davis and Peter Akiki – started working on the model in 2023, hoping to answer a critical gap in the energy and climate debate.
‘When we hear about climate change, we’re typically presented with two opposing scenario archetypes,’ Assoc Prof Hopeward says.
“On the one hand, there are scenarios of unchecked growth in fossil fuels, leading to climate disaster, while on the other hand there are utopian scenarios of renewable energy abundance.”
The students posed the question: what if the more likely reality is somewhere in between the two extremes? And if it is, what might we be missing in terms of risks to people and the planet?
After graduating, the team continued to work with Assoc Prof Hopeward to develop and refine the model, culminating in the publication of ‘GREaSE’ in Energies.
Using the model, the researchers have simulated a range of plausible future scenarios including rapid curtailment of fossil fuels, high and low per-capita demand, and different scenarios of electrification.
According to Richard Davis, “a striking similarity across scenarios is the inevitable transition to renewable energy – whether it’s proactive to address carbon emissions, or reactive because fossil fuels start running short.”
But achieving the rapid cuts necessary to meet the 1.5°C targets set out in the Paris Agreement presents a serious challenge.
As Ms O’Connor points out, “even with today’s rapid expansion of renewable energy, the modelling suggests it can’t expand fast enough to fill the gap left by the phase-out of fossil fuels, creating a 20 to 30-year gap between demand and supply.
“By 2050 or so, we could potentially expect renewable supply to catch up, meaning future demand could largely be met by renewables, but while we’re building that new system, we might need to rebalance our expectations around how much energy we’re going to have to power our economies.”
The modelling does not show that emissions targets should be abandoned in favour of scaling up fossil fuels. The researchers say this would “push the transition a few more years down the road”.
Assoc Prof Hopeward says it is also unlikely that nuclear power could fill the gap, due to its small global potential.
“Even if the world’s recoverable uranium resources were much larger, it would scale up even more slowly than renewables like solar and wind,” he says.
“We have to face facts: our long-term energy future is dominated by renewables. We could transition now and take the hit in terms of energy supply, or we could transition later, once we’ve burned the last of the fossil fuel. We would still have to deal with essentially the same transformation, just in the midst of potentially catastrophic climate change.
“It’s a bit like being told by your doctor to eat healthier and start exercising. You’ve got the choice to avoid making the tough changes now, and just take your chances with surviving the heart attack later, or you get on with what you know you need to do. We would argue that we really need to put our global energy consumption on a diet, ASAP.”
The researchers have designed the model to be simple, free and open source, in the hope that it sparks a wider conversation around energy and climate futures.
Full paper details:
Hopeward, J., Davis, R., O’Connor, S. and Akiki, P. (2025) The Global Renewable Energy and Sectoral Electrification (GREaSE) Model for Rapid Energy Transition Scenarios, Energies 18(9). https://www.mdpi.com/1996-1073/18/9/2205
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Contact for interview: Assoc Prof James Hopeward
M: +61 408 819 175 E: james.hopeward@unisa.edu.au
Media contact: Candy Gibson
M: +61 434 605 142 E: candy.gibson@unisa.edu.au