The Steel Passport

Steel is first in the ESPR queue and it is also one of the best-prepared sectors for a passport, for reasons that have nothing to do with sustainability.

Structural safety has required traceability in steel for decades, which means the identity infrastructure a passport needs largely exists already.

The traceability that already exists

Steel is produced in heats — discrete batches from a furnace — and each heat carries an inspection certificate recording its chemical composition and mechanical properties.

That certificate follows the material through processing and into a structure, because a structural engineer needs to know that a given section meets the grade it was specified as. Few materials have anything comparable.

Production route dominates carbon

Carbon intensity varies enormously between steels, and almost all of the variation comes from one variable rather than from marginal efficiency differences between plants.

The consequence for a passport is that the route matters more than almost any other declared attribute, and a carbon figure for steel without its production route stated is missing the variable that explains most of the number.

Recycled content is already high

Steel is among the most recycled materials in the world, and the electric arc furnace route runs substantially on scrap. This creates a different situation from materials where recycled content is aspirational.

The binding constraint is scrap availability rather than willingness to use it. Steel in service is not available as scrap, and the stock of steel in buildings and infrastructure represents decades of accumulated production that has not yet returned.

Scrap quality is the second constraint and it is where product data matters. Contamination — copper from electrical components, tramp elements from mixed sources — limits what a scrap charge can produce, and knowing composition improves sorting.

Reuse is worth more than recycling

Recycling steel melts it and reforms it, which recovers the material and spends energy doing so. Reusing a section keeps the shape, the properties and the embodied energy already invested in it.

The fourth step is the whole problem and it is an information failure rather than a material one. A structural engineer cannot specify a section whose grade cannot be demonstrated, so a sound beam is melted because its paperwork was lost.

Testing recovered steel to establish its properties is possible and it costs enough to erase the advantage over new material in most cases, which is exactly the search cost a retrievable record removes.

What the passport should carry

The content follows from the above, and most of it is data the sector already produces in a different form.

• Grade and standard, with the chemical composition and mechanical properties from the inspection certificate.
• Production route, because it explains most of the carbon figure.
• Carbon intensity with a stated boundary, per the relevant category rule.
• Recycled content with its custody model.
• Heat identity, so a specific section resolves to the batch it came from.
• Coatings and treatments, which affect both reuse suitability and recycling.

The fifth item is what makes reuse possible decades later, and it is the one requiring the least new work because heat identity is already recorded. What is missing is the durable link between the physical section and that record.

The marking problem

A passport for a steel section needs an identifier that survives fabrication, transport, installation, decades of service and recovery. That is a demanding requirement and it is not solved by a printed label.

Hard stamping, laser marking and cast-in identifiers all survive better than anything applied to the surface, and all can be defeated by cutting a section to length, which is routine. A section cut in two produces one piece carrying the mark and one that does not.

There is no complete answer to this yet, and the honest position is that marking strategy is an open problem for the sector rather than a solved one. Marking at intervals along a section rather than once is the most practical current mitigation.