Fertilisers

Annex I lists 27 fertiliser CN codes spanning ammonia, nitric acid, urea, ammonium nitrate, ammonium sulphate, calcium nitrate and NPK blends. The covered goods checker maps a code to its scope status.

Ammonia is synthesised by Haber-Bosch from hydrogen and nitrogen. The dominant industrial route uses steam methane reforming (SMR) of natural gas to produce the hydrogen feedstock, which carries roughly 1.6-2.0 tCO2 per tonne of ammonia from the SMR step alone, plus combustion CO2 for process heat. Electrolytic (green) ammonia and partial oxidation routes shift the emissions profile materially. The ammonia route is the single largest driver of embedded emissions in downstream nitrogen fertilisers.

Nitric acid is made by catalytic oxidation of ammonia. The process releases nitrous oxide (N2O), a high-GWP gas (GWP100 of 273) that is the principal climate impact of the step. Modern plants fit tertiary or secondary N2O abatement catalysts that reduce N2O by 90-99%; the embedded emissions for nitric acid therefore vary by a factor of ten or more across installations. Verified abatement reduces the installation-specific factor.

Urea is produced by reacting ammonia with CO2. Because the CO2 is chemically bound in the urea molecule, a urea-producing installation may deduct the CO2 input that becomes part of the product from its direct emissions, provided the CO2 is sourced from a process whose emissions were themselves counted (for example, the same site's SMR plant). When urea is later applied to soil the CO2 is released, but that release is not attributed back to the producing installation under CBAM.

Defaults are published per CN sub-good. They reflect the conservative end of the production-route spectrum, so verified actuals from an installation with modern N2O abatement or electrolytic hydrogen will sit well below the default.