Agricultural Inputs — Fertilizer (Nitrogen)

Material Composition Assumptions

The default functional unit is one tonne of nitrogen fertilizer expressed as urea (46-0-0), the most widely traded nitrogen fertilizer globally. Key process inputs and their emission relevance:

• Natural gas (feedstock): ~28 GJ per tonne of ammonia. Natural gas serves dual roles as the hydrogen source (via steam methane reforming) and as fuel for process heat. Approximately 80% of production cost and 60–70% of emissions are attributable to natural gas.
• Natural gas (fuel for compression): Haber-Bosch synthesis requires 150–200 bar pressure; multi-stage centrifugal compression is the primary energy consumer in modern plants.
• Process electricity: ~0.2–0.5 MWh per tonne of urea for instrumentation, pumping, and auxiliary systems. Grid-sourced in most regions.
• Water: Steam methane reforming consumes significant process water; not a material emissions driver but relevant for water stress co-assessment.
• Catalysts: Iron-based catalysts for ammonia synthesis; ruthenium catalysts in some advanced plants. Low mass and low embodied emissions relative to gas inputs.

The Haber-Bosch process yields ammonia (NH₃), which is then converted to urea via reaction with CO₂ captured from the reforming process. This CO₂ is temporarily sequestered in the urea molecule but re-emitted during soil application, counted under Scope 3 field emissions.

Regional feedstock variation is significant: Chinese plants using coal gasification (rather than SMR) produce approximately 4.5–5.0 tCO₂e per tonne of N, roughly double the global average.

Manufacturing Geography

The default manufacturing region is global blended average, covering the four major production regions:

• China (~30% of global production): Predominantly coal-based feedstock, highest emission intensity (~4.5–5.0 tCO₂e/t N).

• Russia (~12% of global production): Natural gas feedstock at competitive prices; ~2.0 tCO₂e/t N, among the lowest globally.

• EU (~9% of global production): Natural gas feedstock with best-in-class efficiency; approximately 2.0–2.3 tCO₂e/t N. Increasingly subject to EU ETS carbon pricing.

• USA (~9% of global production): Gulf Coast natural gas feedstock; approximately 2.2–2.5 tCO₂e/t N.

• Grid intensity: ~500 gCO₂e/kWh used as blended global industrial average for Scope 2 calculation. This overstates EU and understates Chinese grid intensity but is appropriate for a global blended estimate.

• Rationale: International trade in fertilizer means the origin of production is often unknown to the end buyer. A global blended figure is appropriate as the default; buyers with known supply chain provenance should use region-specific factors.

Regional Variation

Production Region	Feedstock	Grid Intensity	Approx. CCI Score
EU (best practice)	Natural gas	~300 gCO₂e/kWh	~2,000 kgCO₂e/t
Russia	Natural gas	~400 gCO₂e/kWh	~2,000–2,200 kgCO₂e/t
USA (Gulf Coast)	Natural gas	~390 gCO₂e/kWh	~2,200–2,500 kgCO₂e/t
Global blended avg	Mixed	~500 gCO₂e/kWh	~2,500 kgCO₂e/t (default)
China (coal-based)	Coal	~580 gCO₂e/kWh	~4,500–5,000 kgCO₂e/t

Note: Field N₂O emissions (Scope 3) are approximately constant across regions at ~0.9–1.2 tCO₂e per tonne of N applied, regardless of production geography. The large regional spread is driven by production process, not use-phase.

Provenance Override Guidance

A supplier or buyer may override the default CCI score by submitting:

1. Product Carbon Footprint (PCF) certified per ISO 14067 or EN 15804, specifying feedstock type (natural gas vs. coal) and production site.
2. Plant-specific energy efficiency data: Heat rate (GJ/t NH₃), electricity consumption (kWh/t urea), and steam generation details.
3. Renewable electricity certification: RECs, PPAs, or green hydrogen certificates for any electrolytic hydrogen in the process stream.
4. Country-of-origin declaration enabling use of the appropriate national emission factor from the IFA regional database.

Fertilizers Europe’s “SUSTAIN” voluntary certification scheme and the Fertilizer Canada product sustainability data sheet program provide structured formats for PCF disclosure. The Ammonia Energy Association is developing standards for “green ammonia” accounting.

Methodology Notes

• CCI score of 2,500 kgCO₂e per tonne (2.5 tCO₂e/t) represents a conservative global blended average for urea production. This sits within the commonly cited range of 2.3–2.8 tCO₂e/t N for gas-based production.
• Scope breakdown: Scope 1 (~35%, ~875 kgCO₂e) covers direct combustion of natural gas for process heat and CO₂ released in the reforming reaction. Scope 2 (~15%, ~375 kgCO₂e) covers grid electricity for compression, instrumentation, and ancillary systems. Scope 3 (~50%, ~1,250 kgCO₂e) covers upstream natural gas extraction and transmission, plus N₂O emissions from field application (using IPCC EF1 default of 0.01 kg N₂O-N per kg N, with GWP100 of 273 per AR6).
• Functional unit: One tonne of nitrogen fertilizer (as urea, 46% N), cradle-to-farm-gate. Field application emissions are included in Scope 3 as they are caused by the product’s use.
• N₂O accounting: The IPCC default emission factor for direct N₂O from nitrogen application (EF1 = 0.01 kg N₂O-N/kg N) translates to approximately 1.2 tCO₂e per tonne of N applied (using GWP100 = 273). Indirect N₂O (from volatilization and leaching) adds a further ~0.3 tCO₂e/t N.
• Data gaps: Actual N₂O emission factors vary significantly with soil type, moisture, pH, and application method. Enhanced efficiency fertilizers (nitrification inhibitors, urease inhibitors) can reduce field N₂O by 20–50% but are not reflected in the default score.
• Coal-based production: The default score explicitly excludes Chinese coal-based production to avoid misrepresenting global supply chains where coal origin is not disclosed. Buyers sourcing from China should apply a 2× multiplier to the Scope 1/2 contribution.