Understanding CBAM for Hydrogen

Hydrogen has been included in CBAM due to its growing importance as an industrial feedstock and energy carrier. The emissions intensity of hydrogen varies dramatically based on the production method, from near-zero for renewable-powered electrolysis to significant emissions for coal gasification routes.

Production Routes and Emissions Sources

Hydrogen production emissions vary by technology:

1. Grey Hydrogen (Steam Methane Reforming):
   • Natural gas reforming (~9-10 kgCO₂/kgH2)
   • Process and combustion emissions
2. Blue Hydrogen (SMR with Carbon Capture):
   • Similar to grey but with CO₂ capture
   • Typically 60-90% emissions reduction
   • Residual emissions from incomplete capture
3. Green Hydrogen (Electrolysis):
   • Emissions dependent on electricity source
   • Near-zero with renewable electricity
   • Grid-connected systems reflect grid intensity
4. Coal Gasification:
   • Highest emission intensity (~18-20 kgCO₂/kgH2)
   • Both process and energy emissions

Special Considerations

1. Electricity Source:
   • For electrolysis, grid emissions factors are crucial
   • PPAs can enable lower emission calculations
   • Requirements for “green” certification
2. Carbon Capture Rates:
   • Varying capture efficiency (60-90%)
   • Energy penalty for capture
   • Compression and storage emissions
3. By-product Hydrogen:
   • From chlor-alkali process
   • Special attribution rules apply

Mathematical Basis

The emissions calculations follow these formulas:

For Steam Methane Reforming (Grey/Blue):

Total Emissions = Process Emissions + Energy Emissions - Captured CO2

Where:
Process Emissions = Natural Gas Input × 0.06 tCO2/GJ
Energy Emissions = Fuel Consumption × Emission Factor
Captured CO2 = Total CO2 × Capture Rate (if applicable)

Typical inputs per tonne H2:
- Natural Gas: 3.5-4.0 tonnes
- Process Energy: 35-40 GJ

For Electrolysis:

Total Emissions = Electricity Consumption × Grid Factor

Where:
Electricity Consumption ≈ 50-55 MWh/tonne H2
Grid Factor varies by country/source
For renewable electricity: must meet additionality criteria

For Coal Gasification:

Total Emissions = Coal Input × EF + Process Energy × EF

Where:
Coal Input ≈ 6-7 tonnes coal/tonne H2
Process Energy includes auxiliary consumption

Data sources:

• Process emissions: IEA Greenhouse Gas Programme
• Energy consumption: Industry benchmarks
• Grid intensity: IEA country-specific data
• Capture rates: EU Innovation Fund data
• Technology parameters: Best Available Techniques Reference Documents (BREFs)