One tonne of steel, and the four places its carbon came from
A CBAM declarant has to report the emissions embedded in each imported good, and past a simple product that means tracing a chain backwards: crude steel carries pig iron, which carries coke and sintered ore, each with its own process and its own emissions. This resolves that chain and says which process actually released the carbon, which is the question an abatement decision turns on and the one a single figure hides.
01The installation
Four processes feeding one another, the smallest chain that behaves like a real one: a shared input reached down two different paths. Every figure is editable and the whole example is invented, so replace it with your own before it means anything.
02Where the carbon was actually released
The specific embedded emissions of crude steel say how much carbon a tonne of it carries, but not whether that carbon came out of the coke oven or the blast furnace, and those are different decarbonisation arguments with different price tags. The split here is by the process that released the emissions rather than by the immediate supplier, so a shared input reached down two paths accumulates into one entry instead of appearing twice.
03Method, and three things it refuses
The arithmetic, written out
- Direct emissions embedded in a processattributed + Σ (qty × SEE direct of precursor)
- Indirect emissions embedded in a processMWh × factor + Σ (qty × SEE indirect of precursor)
- Specific embedded emissions, per tonne of the goodembedded ÷ activity level
Processes are resolved in dependency order, and a precursor is worth its own specific embedded emissions multiplied by the quantity consumed, which is what makes this a chain rather than a sum.
Three refusals
- Direct and indirect never merge, because CBAM reports them separately and the certificate calculation treats them differently, and collapsing them early loses information that cannot be recovered downstream
- A precursor with no stated emissions is refused rather than assumed to be zero, because counting an unstated input as emission free is the most reliable way to understate a good; with no source process inside the installation it needs supplier data or a default value from the current implementing act
- A cycle is an error rather than something to iterate towards a fixed point: if two processes each list the other as a precursor, the chain has no bottom and the honest output is the name of the loop
What this page does not know
It does not know your installation boundary, whether the activity levels were measured or estimated, which monitoring methodology the figures came from, or whether the default values you may be entitled to use are still the current ones. It holds no emission factor of its own and publishes no default, and nothing it prints is a declaration.
Method behind it: the embedded emissions case study