New method of ammonia production could reduce global greenhouse gas production by 2%

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A farmer sprays a liquid fertilizer based on ammonium nitrate and urea on pre-emergent crops. Credit: Flickr.

About 50% of the world’s food production relies on fertilizers based on ammonia, an important source of nitrogen essential for plant growth. In some fields, it is not uncommon to see 90 kg (200 pounds) of ammonia per acre for each growing season. Elsewhere, ammonia is a valuable ingredient used to make pharmaceuticals, plastics, textiles, explosives, and more. In other words, ammonia provides an essential service to modern society. There’s just one problem: Ammonia production is extremely taxing on the environment, being responsible for around 2% of global CO2 production. Its carbon footprint is equivalent to all greenhouse gas emissions emitted by South Africa.

But that could change since scientists at Monash University in Australia developed a new “green” production method for ammonia. To make ammonia today, industrial plants use what is known as the Haber-Bosch cycle, in which methane gas is refined to produce hydrogen, which reacts with nitrogen in the atmosphere to synthesize ammonia. In the process, around six tonnes of carbon dioxide are released for every 1.1 tonnes of hydrogen.

In addition to releasing large amounts of carbon dioxide which warms the atmosphere, the production of ammonia on an industrial scale also causes pollution with nitrates as a by-product, which is often found in rivers and streams. underground waters.

The alternative method of producing ammonia developed at Monash came about as researchers focused on an entirely different goal. During the grim lockdown of COVID 2020, researchers Alexandr Simonov and Bryan Suryanto working in the lab of chemistry professor Doug MacFarlane wanted to make bleach out of salt water using electrolysis – the process of using electricity to divide water into hydrogen and oxygen.

This environmentally friendly bleach could be used to disinfect hospital surfaces while the alkaline byproduct solution is ideal for hand washing, being gentler on the skin than regular soap. But in the process, the scientists realized that the phosphonium salts they were working with could be chemical precursors for making ammonia.

To their amazement, the researchers were able to “produce ammonia at room temperature, at high and convenient rates and efficiency.” No methane – nor any type of fossil fuel for that matter – has been involved in the synthesis of green ammonia, which can be powered by electricity from renewable energy sources.

The prototype used in research to produce “green” ammonia without adding methane. Credit: ACES Electromatériaux.

This isn’t the first time that ammonia has been produced from green sources, but the previous effort has yielded only small amounts, not enough to be at least commercially viable. In fact, when Suryanto shared the results of the experiments with his colleagues, everyone was stunned.

When Suryanto shared the results of the experiments with his colleagues, everyone was stunned by the excellent result.

“To be honest, the eureka moment wasn’t really ‘Eureka!’ It was more like ‘Are you sure? I think you have to do it again, ”Professor MacFarlane said in a statement.

“It takes a long time to really believe it. I don’t know if we’ve really had a real celebration yet. Perhaps the launch of our spinoff company will be the moment when we truly celebrate all of this. “

Monash researchers are currently working with a local company called Jupiter Ionics to commercialize their method of making ammonia.

“The technology opens up a wide range of possibilities for future scale-up to very large production facilities for export, attached to dedicated solar and wind farms,” ​​said Professor MacFarlane.

Unlike the huge giant industrial factories required to produce ammonia on a large scale with the Haber-Bosch technique, the new method can produce green ammonia in much smaller factories.

“You don’t need a huge chemical engineering setup. They can be as small as a thick iPad, and it could produce a small amount of ammonia continuously to run a commercial greenhouse or hydroponic plant, for example, ”Professor MacFarlane said.

“This means that distributed fertilizer production becomes possible because the ammonia plant is so small and simply built,” he added.

Ammonia is obviously coveted in agriculture, but it can also be used very well as a fuel in transport. Much attention is paid to fuel cells which use hydrogen to power vehicles, but ammonia is safer because it is less combustible and it is much easier to store than the lightest molecule in the universe which tends to escape easily from tanks. The biggest downside to ammonia, however, is that it is a significant source of nitrogen oxides that are extremely harmful to our health.

The new findings appeared in the journal Science.

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