Green ammonia

Green ammonia here is ammonia made with renewable electricity. The power comes from the site solar array and battery. Nitrogen is taken from the air by membrane separation. Hydrogen is made by electrolysis. The two gases are compressed together and passed over a Haber-Bosch catalyst. The product leaving the reactor is gaseous ammonia.

That gas can be liquefied, or converted to an ammonium salt. Liquefied ammonia is the form that is stored and moved as a liquid. The salt is the form used where a solid fertiliser is the offtake. The synthesis step does not choose between them. The plant downstream of the reactor does.

The electrolyser does not follow the synthesis loop hour by hour. Hydrogen is held in compressed storage between the electrolyser and the compressor that feeds the catalyst. The store does not replace the synthesis, and the synthesis compression is not the container store: it is the step that raises nitrogen and hydrogen together to the pressure the catalyst needs.