Critical Materials Atlas
Supply structure · the energy footprint

Cheap energy concentrates refining — but read the form of the energy

The atlas calls several refining chokepoints energy-sited. Here it is measured — and honestly. Cheap energy really does pull refining into a few countries, but the form of that energy sets the mechanism: some stages site on cheap power (aluminium, polysilicon, silicon metal); others on cheap fuel plus a co-located reductant or ore (magnesium, ferrochrome, steel, ammonia); and copper smelting shows even a low-energy stage can concentrate — on logistics and policy, not watts. Energy is a primary driver of the map, not a single ruler.

Energy per tonne vs concentration, grouped by what drives the siting. Bars are total primary energy per tonne (MWh/t); each row also states its electricity share of that (elec) and the form of energy that actually sites it. The right column is the stage-matched concentration — the share of the same stage the row describes (refined/smelter/process, never the mine share for a refining stage). Figures are order-of-magnitude literature values; reproducible: build_energy_footprint.py → energy_footprint.json. Sources per row (IMA/Pidgeon LCA, Fraunhofer ISE, IAI, ICSG, worldsteel, IFA, USGS).

Bar = total primary MWh/t · number in bar = t CO₂/t · elec = electricity MWh/t · right = stage-matched top share

Three mechanisms, not one

1 — Power-sited (aluminium, polysilicon, silicon metal). These run on electricity: their feedstock (alumina, quartz) is cheap and shippable, so the price of power dominates and the furnace goes where electricity is cheapest and most reliable. This is the clean “energy chokepoint wearing a metal’s name” case — an ore embargo can’t touch it, a power-price shock can, and diversifying means building at cheap reliable power elsewhere, not opening a mine.

2 — Fuel/reductant-sited (magnesium, ferrochrome, steel, ammonia). Here the energy is mostly not electricity. Magnesium’s Pidgeon retorts are coal-fired batch units (~1–3 MWh/t of electricity; the ~78 MWh/t is primary energy including embodied ferrosilicon) sited on dolomite, ferrosilicon and cheap coal — not on a cheap grid. Steel and ammonia site on coking coal and natural gas as reductant and feedstock. Cheap energy still concentrates them, but as fuel plus a co-located reductant or ore, so the fix is different: it’s about coal, gas and material logistics, not just electricity price.

3 — The control: copper smelting. Low energy (~2.5 MWh/t) — and yet not diffuse: China holds ~40–45% of refined copper. A low-energy stage that concentrated anyway, on concentrate logistics, sulphuric-acid handling and industrial policy. It is the proof that energy intensity is a driver of the map but not the whole of it.

The through-line survives, sharpened: decarbonising and diversifying are often the same project for the power-sited stages — the only way to move polysilicon or aluminium off China’s coal grid and cut ~16–36 t CO2/t is to rebuild them at cheap clean power. For the fuel-sited stages the lever is coal/gas and reductant supply; for copper it is smelter policy. The mechanism map →