Here’s how water, nitrogen and a simple sprayer could revolutionize the production of ammonia

Scientists have developed a simpler, potentially more planet-friendly way to produce ammonia.

A colourless gas with a urine-like smell, ammonia has long been a key ingredient in agricultural fertilizers, helping to feed the world’s growing population. More recently, it has come into the spotlight as a low-carbon alternative to heavy fuel oil in shipping. Ammonia also has an important role to play in decarbonizing power generation and heavy industries such as cement and steel, either in its own right or as a carrier for hydrogen, another net-zero fuel.

Ammonia is mainly produced in bulk using the Haber-Bosch process to synthesize it from hydrogen and nitrogen. However, this century-old method requires large manufacturing facilities and is highly energy intensive. It also relies heavily on fossil fuels to provide both the required heat and feedstocks such as natural gas to synthesize hydrogen.

Not surprisingly, ammonia production generates 1.3% of global CO2 emissions. And this is just to satisfy the current annual worldwide demand. It neither accounts for feeding a growing world population nor the anticipated demand for the gas as a low-carbon fuel.

A new process developed at Stanford University might take ammonia production onto a more sustainable – and lower-cost – path.

The solution appears comparatively simple. It uses water, nitrogen and a sprayer.

The researchers applied an iron oxide catalyst to a graphite mesh, which was then fitted inside a gas-power sprayer. When they put a mixture of water and nitrogen through it, the droplets coming out of the sprayer contained ammonia, indicating a catalytic reaction between the nitrogen and the hydrogen in the water molecules.

At present, the method has only been used in a lab setting. If it could be scaled to a commercial level, the researchers believe it has the potential to significantly reduce the CO2 emissions associated with the traditional synthesis of ammonia.

Because of its simplicity, the technology could also be made portable to generate ammonia right where it’s needed, for example on farms. This could, in turn, reduce the need to transport ammonia from large-scale factories to its point of use, resulting in further fuel and emission savings.

However, the method uses nafion, a type of PFAS (per- and polyfluoroalkyl substances) which face a ban from the European Chemicals Agency. Alternatives may therefore need to be found.

Stanford’s researchers are not the only ones working on making ammonia production greener. The fertilizer and energy industries are also aiming to scale low-carbon and carbon-free methods to synthesize hydrogen from water, using two main methods.

“Green” ammonia is produced using excess electricity from renewable energy sources such as solar or wind power to split hydrogen from water through electrolysis. Alongside, “blue” production methods continue to use hydrogen derived from natural gas but employ carbon sequestration technology to capture most of the CO2, and either store it permanently or use it in other industries.

The World Economic Forum’s Global Risks Report 2023 shows that a food supply crisis is the fourth most highly ranked risk in 2023 overall. Resolving the impact of ammonia production on the environment will be vital to increasing food production in a sustainable way.

It may also distribute production more widely in geographic terms. Russia is one of the largest hubs for mineral fertilizers, but the country’s war in Ukraine has led to fertilizer shortages in the rest of the world, despite fertilizers being exempt from sanctions.

What is more, given the anticipated growth in demand for ammonia from power generation, transportation and industry, green ammonia production will also help make a dent in CO2 emissions on a much wider scale.