What it is
PEM handles variable renewable power well, which is exactly what a hydrogen project needs. The catch is iridium: world production is a few tonnes a year and PEM needs it on every anode.
The material bill
Scale it up →Quantities are per MW of capacityindicative range
| Material | Low | High | Unit | Basis |
|---|---|---|---|---|
| Copper critical | 500.0 | 1,500 | kg | Very high-current power delivery |
| Titanium critical | 200.0 | 600.0 | kg | Bipolar plates and porous transport layers |
| Iridium critical Loadings are falling but remain the binding constraint. | 0.3 | 0.7 | kg | Anode catalyst loading |
| Platinum critical | 0.1 | 0.3 | kg | Cathode catalyst |
Indicative range compiled from published technology studies and chemistry; verify against a manufacturer specification before use. Rows marked “trace” contain the material in quantities too small to state usefully as a mass — the constraint there is purity or supplier count, not tonnage.
The alternatives
Substitution is the most underrated force in materials. When a metal gets expensive or politically difficult, engineers design around it — and demand for a whole mine can evaporate.
Alkaline Electrolyser
The century-old design: steel, nickel and potassium hydroxide, with no precious metals at all.
HVDC Transmission Cable
High-voltage direct-current cable, the technology used to move power hundreds of kilometres with low loss.
Pressurised Water Reactor
The most common reactor design: enriched uranium fuel in zirconium tubes, water as both coolant and moderator.
Three-Way Catalytic Converter
The ceramic honeycomb in an exhaust that converts three pollutants at once, coated in platinum-group metals.