Foundation 1: Ammonia

Ammonia (NH₃), is the first step in the production of Nitrogen fertiliser. The production methods vary, with the main quantity produced using natural gas or coal. This is known as Grey ammonia. Approximately 80% of the ammonia produced globally is used to synthesise nitrogen-based fertilisers like urea and ammonium nitrate.

Production Methods

Hydrogen is produced using Steam Methane Reforming (SMR). Methane reacts with steam at high temperatures (700–1,000°C) in the presence of a nickel-based catalyst, producing hydrogen and carbon monoxide. Water-Gas Shift Reaction is then used on the carbon monoxide produced reacting with more steam to produce additional hydrogen and carbon dioxide.

Nitrogen which is gathered from the air using an Air Separation Unit (ASU). Atmospheric air, which consists of approximately 78% nitrogen, serves as the primary source. To extract nitrogen at high purity, air separation units (ASUs) are employed, leveraging either cryogenic distillation or membrane separation technologies.

Developed in 1913 by Fritz Haber and Carl Bosch, the process enables the synthesis of Ammonia gas, through the reaction of Nitrogen and Hydrogen gas. The process requires 150-200 bar of pressure and a temperature of 400-500 degrees Celsius, as well as the presence of an Iron based catalyst. The produced gas is then condensed and collected as a liquid for storage and transportation.

Use in Agriculture

Ammonia (NH₃) and Hydrogen (H₂) play critical roles in fertiliser production and emerging energy applications. Ammonia, a key nitrogen carrier, is widely used in fertilisers like urea and Ammonium Nitrate, while Hydrogen is essential for Ammonia synthesis via the Haber-Bosch process.

Ammonia's addressable market is growing with its potential low GHG emission fuel.. It is easier to transport and store than Hydrogen due to its higher volumetric energy density and less demanding storage conditions, requiring only -33°C and moderate pressure.. It also benefits from established global infrastructure, making it a practical solution for long-distance transport and a viable hydrogen carrier.

Although Ammonia combustion produces Nitrogen Oxides (NOₓ), proper mitigation technologies exist. Its dual functionality as a fertiliser and energy carrier, combined with easier handling and compatibility with existing infrastructure, positions ammonia as a versatile alternative or complement to hydrogen in global decarbonisation efforts.

Additional Information

Other methods of production include Blue, Green and Pink.

• Blue uses carbon capture and storage (CCS) to reduce the carbon footprint.
• Green uses Renewable energy sources to power electrolysis for the production of Hydrogen.
• Pink is the use of Nuclear energy for the production of Hydrogen.

Technical Notes.

• Steam Methane Reforming Calculation:  CH₄ + H₂O → CO + 3H₂ (ΔH = +206 kJ/mol)
• Water-Gas Shift Reaction:  CO + H₂O → CO₂ + H₂ (ΔH = -41 kJ/mol)
• Haber Bosch Reaction: N₂ + 3H₂ ⇌ 2NH₃ (ΔH = -92.4 kJ/mol)

Cryogenic Distillation: Air is compressed and cooled to extremely low temperatures (-196°C or lower), causing its components to liquefy. Oxygen (O₂), Nitrogen (N₂), and Argon (Ar) have different boiling points, allowing them to be separated by distillation. This method produces high-purity nitrogen (up to 99.999%) and other gases like Oxygen and Argon as valuable co-products.

Membrane Separation: Compressed air is passed through a semi-permeable membrane. Faster-moving gases like oxygen and water vapour diffuse through the membrane, leaving a nitrogen-rich stream. Typically produces nitrogen with a purity of 95–99%, sufficient for many applications.