Mon. Apr 12th, 2021

Ammonia has been in widespread use only since the beginning of the 20th century, but it is already one of the cornerstones of our civilization. It is actually incredible how important ammonia is for us – it is very important for our agricultural productivity. Sadly, manufacturing ammonia is associated with huge carbon emissions, but now scientists from  the University of Sydney and the University of New South Wales are ready to change that.

Ammonia is most commonly used as a fertilizer. Image credit: Playaelyaque via Wikimedia (CC BY-SA 3.0)

Ammonia is very important for making fertilizers – it is key to that. And without fertilizers we probably couldn’t maintain a proper food production to feed us. Of course, you may point out natural fertilizers, but those are actually quite expensive and probably wouldn’t be enough anyway. In the future ammonia could also be used as a fuel or as a medium to transport hydrogen just that little bit easier. For now though ammonia is very energy-intensive to produce, which means that it is linked to unpleasantly dirty emissions.

Currently most ammonia is produced in a Haber-Bosch process. In this process hydrogen (H2) reacts with nitrogen (N2) at high temperatures (450 °C) and pressure (10 MPa). Ammonia production is responsible for 1-2 % of global  energy demand, around 3 % of carbon emissions and 3-5 % of natural gas demand. Scary numbers, right?

But now scientists have developed a new method using plasma. They created a cylinder, where plasma is created inside of the water bubbles. This creates reactive water which can then be processed in a second electrochemistry reactor. This process requires less energy, which can be taken from renewable sources, such as solar. While hydrogen is used, it is created in the same process, which streamlines it.

Reaction column where plasma is created in water bubbles. Credit: Professor Patrick ‘PJ’ Cullen, University of Sydney

Speaking of hydrogen, it is one of the reasons why we are likely to need more ammonia in the future. Liquid ammonia stores more hydrogen than liquid hydrogen itself.  It makes it easier to store hydrogen and use it as a fuel. Making ammonia in a green way is therefore very important for the future of sustainable fuels. As well as sufficient food supply in the world where the population just keeps growing. David Alam, co-author of the study, said: “by advancing plasma technology synergistically with electrolysis, we have created sustainable ammonia, which provides an exciting new path for future chemical production.”

Ammonia is very important for us, but it is also very much not green at all. We have to improve manufacturing methods to a point where ammonia can be produced cheaply and without much problems for the environment. Hopefully, new plasma technologies can help us achieve that.


Source: University of Sydney

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