UNSW engineers have tackled a longstanding problem at the heart of global agriculture: how to make urea for fertiliser without the intensity of emissions associated with fossil-fuel-powered factories.
The solution is outlined in a study published recently in Nature Communications.
Corresponding author Associate Professor and Scientia Fellow Dr Rahman Daiyan from UNSW Sydney’s School of Minerals and Energy Resources Engineering says the work is part of a broader push to go beyond the global move to green ammonia, focusing instead on decarbonising the entire fertiliser chain.
“Urea is the fertiliser used to feed the crops for more than half of the world’s population,” Dr Daiyan says. “But currently, it’s made from natural gas or coal. It’s a very fossil-fuel intensive, high-temperature, high-pressure technology with huge emissions.”
Two problems, one solution
Industrial activities release enormous amounts of carbon dioxide (CO₂) into the atmosphere each year, with around 40 billion tonnes released in 2024 alone. At the same time, nitrogen pollutants such as nitrate and nitrite – collectively referred to as NOₓ species – from agriculture and industry contaminate waterways and ecosystems.
The UNSW study brings these two problems together. Using renewable electricity to trigger an electrochemical reaction, the researchers could directly couple CO₂ with nitrogen pollutants to form urea.
“Making carbon and nitrogen bond together in a controlled and reliable way is extremely difficult,” says the study’s first author, UNSW PhD student Putri Ramadhany.
“To overcome this challenge, we designed a catalyst that works at an atomic scale and can hold carbon- and nitrogen-based molecules together long enough for them to react,” she says.
The UNSW-developed catalyst – made of copper and cobalt – demonstrated a strong synergy between the two metals, and improved urea production when compared with existing systems.
Dr Daiyan says it’s a promising foundation for a circular process that, in future, could convert captured carbon dioxide and nitrogen pollutants into urea. This, he says, is a route that removes pollution, creates valuable chemicals and runs on renewable electricity.
“We’ve been trying to look into pathways for decarbonising urea production,” Dr Daiyan says.
“The vision is zero-carbon urea where we directly couple waste carbon dioxide with nitrogen pollutants using renewable electricity, rather than relying on ammonia as an intermediate.
“That allows us to run the system on solar and wind, avoid high temperatures and pressures and reduce emissions.”
The groundwork for industrial scale-up
While most fundamental research ends at benchtop experiments, the UNSW team is taking these findings and scaling these up using urea electrolysers, which is the equipment considered a benchmark for industrial translation.
To understand how the material behaved under real-world conditions, the team used advanced electron-beam characterisation at the Australian Synchrotron. Here, they could watch the chemical reactions take place in real-time, laying the groundwork for future scale-up.
Why urea for Australia?
Although Australia is a major agricultural exporter, it does not produce enough urea domestically and so is a net importer of the fertiliser – relying heavily on overseas supply to meet demand.
In 2024, urea imports reached around 3.8 million tonnes. Dr Daiyan says this dependence is “a pity” as well as a strategic vulnerability.
If Australia could produce its own clean, locally made urea from waste carbon and renewable electricity, it would strengthen supply chains while lowering emissions. This is especially important as the government regulation of emissions starts to go beyond carbon dioxide.
Does carbon capture and conversion work?
Dr Daiyan says he is mindful of the carbon sources he works with. He says the aim is to use unavoidable emissions from cement factories or biogenic sources like agricultural waste.
The technology is still under development, but early results show promising selectivity under laboratory conditions. Rather than relying on direct air capture, the approach is designed to use carbon dioxide that is already generated from these industrial and biogenic emission streams.
Ultimately, Dr Daiyan sees this research as part of a bigger shift towards circularity – using waste carbon for materials that require carbon dioxide for production: fuels, chemicals, plastics and other manufacturing.
He recently spoke about this issue at COP30 – the 30th session of the United Nations Climate Change Conference.
“At COP, I spoke to governments about the technological pathways we need,” he says.
“This is one of them – there’s enough carbon dioxide around. We just need to start thinking and investing in a circular economy.”
He says getting technologies like this from lab to industry typically takes more than a decade – but this project may move faster.
“Hopefully it will take us another two or three years to get to the stage where we can get an industry partner onboard,” he says.
Dr Daiyan says transforming carbon dioxide and nitrogen pollutants into valuable products helps move the world closer to a cleaner, smarter and more circular chemical future.
“Our work highlights how thoughtful catalyst engineering paired with real-time characterisation can turn environmental problems into opportunities.”
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