# What does a CBAM calculation for steam reforming hydrogen look like?

Canonical: https://senseible.earth/answers/cbam-hydrogen-worked-example-steam-reforming

The Commission's example: a steam reformer burning 190,000 tonnes of natural gas and exporting 800 TJ of heat emits 461,765 t CO2 net, over 55,000 t of hydrogen. That is 8.396 t CO2 per tonne. With 2028 free allocation of 4.580, importing 100 tonnes leaves 381.6 certificates.

## What is monitored

One production process. The only source stream is natural gas, used as feedstock and fuel. Hydrogen is a simple good, so there are no precursors, and only direct emissions count. Heat exported to the rest of the plant or a district network is subtracted. For heat of unknown origin the default is natural gas at 90% boiler efficiency, which is 62.3 t CO2 per TJ.

## Free allocation and the import

Hydrogen has one benchmark whatever the route: 5.089 t CO2 per tonne of hydrogen. The example assumes year 2028, CSCF 1.00 and CBAM factor 90%. Captured CO2 sent to storage could also be deducted, if the receiving site monitors under CBAM.

## Steam reforming, hydrogen, import in 2028 (Commission's example)

- Natural gas: 190,000 t x 48 GJ/t = 9,120 TJ; x 56.1 t CO2/TJ = 511,632 t CO2
- Heat export: 800 TJ x 62.3 t CO2/TJ = about 49,867 t CO2, subtracted
- Total direct emissions: 461,765 t CO2
- Hydrogen made: 55,000 t, so specific embedded emissions = 8.396 t CO2 per t
- Free allocation: 5.089 x 0.90 x 1.00 = 4.580 t CO2 per t
- Import of 100 t: 839.6 t CO2 less 458.0 t CO2 = 381.6 certificates, before any carbon price deduction

Figures are the Commission's own worked example in Guidance No. 5b, not a real plant. Your numbers will differ.

## What Senseible does here

Senseible reads natural gas invoices into dated, fingerprinted quantities, which is the largest input line in a reformer's calculation. The heat export, free allocation and import steps are done in the Commission's template.

- [Default value for Indian hydrogen](https://senseible.earth/answers/cbam-default-value-india-hydrogen)
- [Grey hydrogen: installation steps](https://senseible.earth/answers/cbam-grey-hydrogen-smr-installation-steps)
- [Free allocation with actual data](https://senseible.earth/answers/cbam-free-allocation-actual-data-formula)

Sources: [European Commission, CBAM Guidance No. 5b, hydrogen (14 August 2026), sections 3.1 and 4](https://taxation-customs.ec.europa.eu/document/download/04ceca3b-466e-4ed9-a1a5-a47c2e5e5be0_en?filename=Guidance%20No.%205b%20-%20Sector-specific%20guidance%20document%20on%20hydrogen.pdf)

Last reviewed 2026-10-25.