Understanding CBAM for Fertilisers

The fertiliser sector represents one of the most complex areas under CBAM due to its multiple production pathways and greenhouse gases. From ammonia production through to final blended fertilisers, accurate emissions calculations must account for both CO₂ and N₂O emissions, as well as the emissions embedded in precursor materials.

Production Chains and Emissions Sources

Fertiliser emissions stem from several interconnected production processes:

1. Ammonia Production (CO₂)
   • Natural gas reforming (~2.0 tCO₂/t ammonia)
   • Coal gasification (~3.5 tCO2/t ammonia)
2. Nitric Acid Production (N₂O, CO₂)
   • N2O emissions (~0.2-2.0 tN₂O/t nitric acid)
   • Process CO₂ emissions
3. Urea Production
   • Process emissions minus CO₂ used from ammonia production
4. Mixed/Blended Fertilisers
   • Emissions from precursors
   • Additional processing emissions

Special Consideration: N2O Emissions

Nitrous oxide (N₂O) has a Global Warming Potential (GWP) of 265, meaning each tonne of N₂O emissions equals 265 tonnes of CO₂ equivalent. This makes N₂O abatement in nitric acid production particularly important.

Mathematical Basis

The emissions calculations follow these formulas:

For Ammonia:

Ammonia Emissions = Process Emissions + Energy Emissions - CO2 Transfer

Where:
Process Emissions = Natural Gas Input × 1.02
Energy Emissions = Fuel Consumption × Relevant Emission Factor
CO2 Transfer = CO2 used in urea production (if applicable)

For Nitric Acid:

Total Emissions = CO2e from N2O + Direct CO2

Where:
CO2e from N2O = N2O emissions × 265 (GWP factor)
N2O emissions = Production Volume × Emission Factor
Emission Factor varies by abatement technology:
- No abatement: ~6 kgN2O/t HNO3
- Secondary abatement: ~2.5 kgN2O/t HNO3
- Tertiary abatement: ~0.5 kgN2O/t HNO3

For Urea:

Total Emissions = Ammonia Emissions + Process Emissions - CO2 Uptake

Where:
CO2 Uptake = 0.733 × Urea Production
(based on stoichiometric ratio: 0.733 tCO2/t urea)

For Mixed Fertilisers:

Total Emissions = Σ(Precursor Content × Precursor Emissions) + 
                 Process Emissions

Where:
Precursor Content = Share of N from each source
(ammonium, nitrate, urea)
Process Emissions = Energy use for granulation/blending

Data sources:

• Process emissions factors: EU ETS benchmarking data
• N2O emission factors: IPCC Guidelines
• Energy consumption: IEA data
• GWP values: IPCC Fifth Assessment Report
• Production ratios: EU Best Available Techniques Reference Documents (BREFs)