Australian scientists develop fossil-fuel-free ammonia production using electricity and air

For more than a century, the world has made ammonia the same way: by forcing nitrogen and hydrogen together under extreme heat and pressure, a process that demands enormous amounts of natural gas and leaves a carbon footprint the size of an entire industrial sector. Now a team at the University of Sydney has found a different path—one that uses only air and electricity, mimicking the chemistry of lightning to strip nitrogen and oxygen from the atmosphere and reassemble them into ammonia gas.

Ammonia matters because it feeds the world. Nearly half of all global food production depends on fertilizers made from it, and the Haber-Bosch process, invented in the nineteenth century, still accounts for 90 percent of the ammonia we produce today. The appetite for it only grows. But the process is centralized, energy-intensive, and economically viable only when built near cheap sources of natural gas. It also requires the ammonia to be shipped long distances, adding cost and emissions at every step.

Professor PJ Cullen and his team at the University of Sydney's School of Chemical and Biomolecular Engineering have spent six years pursuing what the scientific community calls green ammonia—a decentralized, scalable method that doesn't depend on fossil fuels. Their breakthrough, published in Angewandte Chemie International edition, works in two stages. First, they use electricity to excite nitrogen and oxygen molecules in air, creating plasma. Then they pass these energized molecules through a membrane-based electrolyser—a silver box that looks unremarkable but does the essential work—where the excited molecules convert into gaseous ammonia.

The advantage over previous attempts is significant. Other laboratories have produced ammonia in solution form, which requires additional energy and processing steps to transform it into the gas needed for practical use. The Sydney team's method produces ammonia gas directly, a more straightforward pathway. Cullen described the finding as signaling a new phase in making green ammonia possible, though he was clear about what remains undone: the plasma component is already viable in terms of energy efficiency and scalability, but the electrolyzer component still needs work to become competitive with the century-old industrial standard.

The implications extend beyond fertilizer. Ammonia contains three hydrogen molecules, making it an effective carrier and storage medium for hydrogen itself—a property that has caught the attention of the shipping industry, which generates about 3 percent of global greenhouse gas emissions. By cracking ammonia to separate the molecules, ships could access hydrogen as a carbon-free fuel. The chemical's potential as an energy source adds another dimension to why this breakthrough matters: it's not just about feeding people more sustainably, but about powering industry without fossil fuels.

The path forward is clear but demanding. The team must push the energy efficiency of the electrolyzer component until the entire two-step process becomes economically competitive with the Haber-Bosch method. Only then will the technology move from laboratory success to industrial scale. For now, the Sydney researchers have demonstrated that the fundamental chemistry works—that air and electricity can be converted into one of the world's most essential chemicals. The next phase is proving it can be done as cheaply and efficiently as the fossil fuel method it aims to replace.