Zero-Carbon Fertiliser Breakthrough: UNSW Sydney's Waste CO2 Conversion Study

The Groundbreaking UNSW Sydney Discovery in Sustainable Fertiliser Production

At the University of New South Wales (UNSW) Sydney, a team of innovative chemical engineers has unveiled a transformative technology that converts waste carbon dioxide (CO₂) and nitrogen pollutants into urea, the world's most widely used nitrogen fertiliser. This zero-carbon fertiliser breakthrough promises to revolutionise agriculture by slashing the massive emissions tied to traditional production methods while simultaneously tackling waterway pollution from excess nitrates.

The process harnesses renewable electricity to drive an electrochemical reaction, directly coupling CO₂ from industrial exhausts or agricultural waste with nitrogen oxides (NOₓ) like nitrate and nitrite found in wastewater. Unlike conventional urea manufacturing, which guzzles natural gas or coal under extreme heat and pressure, this method operates at ambient conditions, powered by solar or wind energy, making it a true net-zero solution.

Led by Associate Professor Rahman Daiyan, a Scientia Fellow and Australian Research Council (ARC) Discovery Early Career Researcher Award (DECRA) recipient in the School of Minerals and Energy Resources Engineering, the research exemplifies UNSW's leadership in industrial decarbonisation. First author Putri Ramadhany, a PhD candidate, meticulously designed the copper-cobalt catalyst that makes this atomic-level bonding possible.

The Global Challenge of Urea Production Emissions

Urea, a cornerstone of modern farming, nourishes crops feeding over half the global population. Yet its production via the Haber-Bosch process consumes about 2 percent of the world's energy and emits roughly 1.2 gigatonnes of CO₂ equivalent annually—comparable to global aviation. In Australia, agriculture accounts for around 18 percent of national greenhouse gas emissions, with fertiliser manufacturing exacerbating supply chain vulnerabilities as the country imported 3.8 million tonnes of urea in 2024 despite being a top exporter of grains and livestock.

Nitrogen runoff from over-fertilisation pollutes rivers and oceans, creating dead zones and harming biodiversity. The UNSW breakthrough addresses both ends: capturing unavoidable CO₂ from cement plants or biogas while neutralising NOₓ pollutants that plague waterways. This dual benefit aligns perfectly with Australia's net-zero ambitions and the global push for sustainable intensification in farming.

Traditional methods involve synthesising ammonia first, then reacting it with CO₂—energy-hungry steps that lock in fossil dependence. UNSW's direct C-N coupling skips these, potentially cutting energy use by over 30 percent and enabling on-farm or regional production.

How the Electrochemical Process Works: A Step-by-Step Breakdown

The ingenuity lies in a bimetallic copper-cobalt (Cu-Co) catalyst deposited on carbon supports via co-sputtering. Here's the process:

• Input Capture: Waste CO₂ from flue gases and NO₂⁻/NO₃⁻ from wastewater are fed into an electrolyser cell.
• Electrochemical Activation: Renewable electricity applies a potential of -1.2 V vs. reversible hydrogen electrode (RHE) at neutral pH, reducing CO₂ to *CO intermediates and NO₂⁻ to *NH₂.
• C-N Coupling: The Cu-Co synergy stabilises these radicals, enabling *CO + *NH₂ → *NH₂CO, the rate-limiting step confirmed by density functional theory (DFT) models.
• Urea Formation: Sequential proton-coupled electron transfers yield urea (CO(NH₂)₂), with Faradaic efficiency up to 11 percent and yield rates of 61 mmol h⁻¹ g_cat⁻¹.
• Output Purification: Products quantified via NMR and chromatography; catalyst stable for 48+ hours.

In situ synchrotron techniques at the Australian Synchrotron provided real-time insights into dynamic site evolution, validating the tandem relay mechanism.

Behind the Innovation: The UNSW Research Team

Dr Rahman Daiyan's expertise spans artificial photosynthesis, electrocatalysis, and power-to-X fuels, with over 95 publications and leadership in UNSW's Particles and Catalysis Research Group. His vision for zero-carbon urea stems from prior work on green ammonia and CO₂ electroreduction. PhD student Putri Ramadhany overcame the 'sticky' challenge of C-N bonding through precise catalyst engineering, showcasing the hands-on training vital in Australian higher education.

Collaborators including Jodie Yuwono and Rosalie Hocking leveraged advanced facilities like the Australian Synchrotron, highlighting interdisciplinary strengths at UNSW. The paper, published in Nature Communications (DOI: 10.1038/s41467-026-68481-6), underscores open-access impact for global researchers.

This project ties into UNSW's Institute for Industrial Decarbonisation, launched in 2024, uniting faculties to net-zero heavy industries like fertiliser.

Environmental Impacts: Cleaner Skies, Rivers, and Farms

Globally, fertiliser production rivals aviation's footprint; in Australia, imported urea embeds high embodied emissions. Local zero-carbon production could cut ag's 17.9 percent share of national GHGs. By remediating NOₓ—responsible for algal blooms—the tech protects the Great Barrier Reef and Murray-Darling Basin.

A table illustrates potential savings:

For Aussie wheat and canola growers, this means resilient, low-emission inputs amid volatile global prices.

Australia's Agricultural Landscape and Fertiliser Dependence

Australia's $80 billion ag sector exports $60 billion annually, yet relies on imports for 90 percent of urea needs. Climate variability and supply shocks—like 2022's global crunch—highlight risks. This breakthrough supports the National Agrifood Decarbonisation Strategy, enhancing food security while meeting EU Carbon Border Adjustment Mechanism demands.

Trials could integrate with biogas from dairy waste, creating farm-scale electrolysers. Stakeholders from Fertiliser Australia praise such innovations for nitrogen use efficiency (NUE), reducing field emissions by 30 percent via precision application.

Related efforts at other Aussie unis, like UQ's green ammonia pilots, complement UNSW's work. For aspiring researchers, opportunities abound in higher ed research jobs tackling climate-ag intersections.

Scaling Up: From Lab to Field Challenges and Solutions

• Catalyst Durability: Achieved 48-hour stability; next, 1000+ hours via doping.
• Electrolyser Design: Urea-specific stacks benchmarked against PEM tech.
• Feedstock Sourcing: Biogenic CO₂ from piggeries; nitrate from sewage.
• Economics: Renewable integration drops costs below $500/t urea.
• Policy Support: Aligns with Safeguard Mechanism reforms.

Dr Daiyan eyes industry pilots in 2-3 years, leveraging ARC Linkage grants. UNSW's tech transfer arm accelerates commercialisation.

UNSW's Broader Commitment to Sustainable Research

Building on silver-atom catalysts (2025) and AI-optimised ammonia (2025), this fits UNSW's decarbonisation ecosystem. The ARC Centre of Excellence in Transformational Electrochemistry powers such advances.

For students, programs like how to excel as a research assistant prepare for roles in green chem eng.

Career Opportunities in Australia's Green Research Sector

This breakthrough spotlights demand for electrochemists, materials scientists, and agrotech experts. UNSW's PhD scholarships and postdocs offer pathways, with higher ed postdoc jobs booming in sustainability.

Professionals can advance via postdoctoral success tips, positioning for leadership in net-zero industries.

Photo by mae black on Unsplash

Future Outlook: A Fertiliser Revolution on the Horizon

With scaling underway, zero-carbon fertiliser could hit markets by 2030, aiding Australia's 43 percent emissions cut target. Globally, it supports UN SDGs 2, 13, and 14.

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