Aluminium sustainability

Production footprint (cradle-to-gate)

Primary aluminium ≈ 14.8 kg CO₂e/kg (IAI 2023 global average, mine-to-cast-house). This is roughly six times steel per kg, because smelting is extremely electricity-intensive (the Hall–Héroult process). The number is a global average only: hydro-powered smelters can be a small fraction of it, while coal-grid smelters are well above. Do not apply 14.8 to a specific supply chain without checking its power source.

Electricity sensitivity

Because electrolysis energy dominates, the smelter's grid is the single biggest lever — far more than transport or alloying. This is why "low-carbon aluminium" offers exist and why a credible number requires knowing the electricity source, not just the metal.

Recycled aluminium

Recycling aluminium saves the great majority of the primary energy and GHG. However, the recognised recycled-processing figure is reported on a gate-to-gate boundary (scrap in → metal out), which is not directly comparable to the cradle-to-gate primary number — placing them side by side would mislead. MatQuo therefore does not net a recycled figure against 14.8, and its comparison tools refuse a primary-vs-recycled numeric comparison until a like-for-like boundary is available. A harmonised recycled-content scenario is a known data gap.

Lightweighting

Aluminium's advantage in transport applications is that a part can be much lighter — but a lighter part with a higher per-kg footprint does not automatically have a lower production footprint. Test it with your own part weights in the lightweighting calculator (the default steel→aluminium example shows exactly this tension).

Methodology & limitations

Boundary: cradle-to-gate (mine to cast-house). Source: International Aluminium Institute, 2023 global average. Functional unit: 1 kg primary aluminium. Aluminium is a CBAM good — see the tariff page.