Australian researchers release open-source model assessing renewable growth and long-term global power shortfalls
Renewable energy is expanding fast — and it still may not be enough to prevent a decades-long global power shortfall
The world has spent decades arguing about two energy futures: one where fossil fuels burn unchecked until the climate breaks, and one where renewables rise smoothly to replace them. Neither story leaves much room for what happens in between.
A team of Australian researchers suspects that middle ground is exactly where the real risk lies — and they built a free, open-source model to explore it.
That openness also invites scrutiny — the researchers aren’t claiming GREaSE has all the answers, only that it asks questions other models tend to avoid.
A model built to explore the uncomfortable middle ground
GREaSE — short for Global Renewable Energy and Sectoral Electrification — was developed at the University of South Australia by Associate Professor James Hopeward alongside civil engineering graduates Shannon O’Connor, Richard Davis, and Peter Akiki. The project began in 2023 as an Honours thesis, driven by a question the students felt conventional models weren’t answering. After graduating, the team kept working and eventually published the tool in the open-access journal Energies.
The model is deliberately simple, free, and open-source — a design choice, not a limitation. Most major energy and climate models anchor around extreme scenarios: unchecked fossil fuel growth at one end, smooth renewable abundance at the other. GREaSE was built to test the space between those poles, where Hopeward and his colleagues believe the real risks are hiding.
The core question: what if the most likely future is neither catastrophe nor utopia — and what dangers does that middle path conceal?
What the simulations reveal about the energy transition
To explore this, the team ran GREaSE across a range of plausible futures. The simulations varied the pace of fossil fuel curtailment, tested high and low per-capita energy demand, and modeled different rates of electrification across sectors — not to predict a single outcome, but to reveal patterns.
One pattern appeared consistently. As Richard Davis put it, “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.” The direction of travel isn’t in question. The timeline is.
That’s where the findings get uncomfortable. Even with renewable energy expanding at today’s historically rapid pace, the modelling suggests it can’t scale fast enough to replace fossil fuels as they’re phased out — at least not if the world is serious about meeting the 1.5°C target set by the Paris Agreement. What the model projects instead is a 20-to-30-year gap between energy supply and demand.
By around 2050, renewable supply could finally catch up. But the intervening decades present a serious structural challenge: economies would still be running on a system being dismantled faster than its replacement can be built, and most policy conversations don’t directly address that.
Why delaying the transition — or turning to nuclear — won’t close the gap
Two workarounds come up most often: slow down the fossil fuel phase-out, or accelerate nuclear power development. The GREaSE team addressed both. Neither holds up under scrutiny.
On fossil fuels, the researchers are direct. Scaling them back up would push the transition a few more years down the road while making climate outcomes worse in the meantime. The gap doesn’t disappear — it just shifts.
Nuclear is a more tempting argument, but the numbers don’t support it. Global uranium resources are limited, and even if they weren’t, nuclear capacity scales up far more slowly than solar and wind. It can’t bridge a 20-to-30-year shortfall on any realistic timeline.
Hopeward’s analogy cuts through the complexity. Delaying the transition, he says, is like ignoring a doctor’s advice to change your diet and gambling on surviving the heart attack instead. The underlying condition doesn’t go away — the fundamental transformation is unavoidable. The only variable is whether it happens now, with manageable disruption, or later, in the middle of potentially catastrophic climate conditions.
Rethinking energy expectations for the decades ahead
If the gap is real and the workarounds don’t work, something else has to give. The researchers point to expectations — specifically, the assumption that economic growth can keep running on the same volume of energy it consumes today while the transition is underway.
Reducing global energy consumption isn’t a fringe idea in the GREaSE framework. Hopeward describes it as essential, framing it as a global “energy diet” that societies need to start now. The language is accessible by design, reflecting the broader purpose behind the tool.
GREaSE was built not just for specialists. By making scenario testing free and open-source, the team is inviting policymakers, researchers, journalists, and ordinary citizens to engage with trade-offs that are usually buried in technical literature. Anyone can run the model, adjust the assumptions, and see what shifts. That openness also invites scrutiny — the researchers aren’t claiming GREaSE has all the answers, only that it asks questions other models tend to avoid.
What to watch for next
The publication of GREaSE in Energies is a starting point, not a conclusion. The model is available for anyone to use, adapt, and challenge. What happens next depends largely on whether the conversation it’s designed to start actually begins — in policy circles, in public debate, and in the institutions responsible for planning infrastructure that will still be operating in 2050.
The energy transition is already underway. The question GREaSE raises is whether the world is planning for the version of it that’s actually coming, or still holding out for the cleaner story where the gap never appears.
Discover more about the study here: 1qJames Hopeward, Richard Davis, Shannon O’Connor, Peter Akiki. The Global Renewable Energy and Sectoral Electrification (GREaSE) Model for Rapid Energy Transition Scenarios. Energies, 2025; 18 (9): 2205 DOI: 10.3390/en18092205
Daniel García is an Editor-in-Chief with strong expertise in structural work and engineering principles. He combines this technical foundation with deep knowledge of energy, spatial design, and emerging technologies, bringing a forward-thinking and analytical approach to editorial leadership.
