Ammonia is a gas that is widely used to make nitrogen fertilisers. Green ammonia production is where the process of making ammonia is 100% renewable and carbon-free. One way of making green ammonia is by using hydrogen from water electrolysis and nitrogen separated from the air. These are then fed into the Haber process (also known as Haber-Bosch), all powered by sustainable electricity. In the Haber process, hydrogen and nitrogen are reacted together at high temperatures and pressures to produce ammonia (NH3).
Reducing the amount of carbon dioxide produced during the ammonia manufacturing process is critical to achieving net-zero targets by 2050. The best way to reduce carbon emissions when making ammonia is to use low-carbon hydrogen. Green hydrogen is produced using water electrolysis to generate hydrogen and oxygen, and the availability of sufficient green energy limits the production capacity of green hydrogen.
A consequence of decarbonised ammonia production is you can’t produce urea. Because urea is made by combining ammonia and the carbon dioxide (CO2) released in the earlier process where hydrogen is split from the carbon source (usually natural gas) to provide the hydrogen in ammonia (NH3) production. So it’s unlikely urea can be part of a decarbonised food chain.
It’s Yara’s goal to decarbonise fertiliser production, but it will require significant ongoing investment in R & D and production capacity. It’s interesting to note that when Yara first began producing nitrogen fertiliser in Norway, back in 1905, the process was carbon-free! The energy source back then was hydro-electricity.