Scandium: Emissions
Why each tonne of oxide carries thousands of tonnes of CO2
What this tab covers The greenhouse-gas footprint of the commodity at a global level, split by lifecycle phase: extraction (or farming), refining and processing, movement, usage, and recycling or end of life. Intensities are per unit of product; the global total combines intensity with world output. Also covers other environmental impacts and the main levers to cut emissions. Emission intensity 3,940 t CO2e per t range 743-5,500 across published routes · cradle-to-gate, Sc2O3 from rare-earth tailings, mass allocation (Wang et al. 2020). Other studies: titanium dioxide acid waste 743 (Zhang et al. 2018); bauxite residue 5,290 with economic allocation or 1,930 with mass allocation (Hengevoss et al. 2024); about 5,500 (Koltun & Tharumarajah 2014) Global emissions per year 0.30 Mt CO2e per year 2025 · 3,940 t CO2e/t x 80 t of oxide (derived); range about 0.06-0.44 Mt using the published spreadPer t of scandium oxide (Sc2O3), cradle-to-gate. Intensity: Hengevoss et al. 2024, Cleaner Waste Systems 7:100129, which reviews the other studies. Global total: Derived from Hengevoss et al. 2024 and USGS MCS 2026.
Share of footprint by lifecycle phase
Refining / processing 96%Footprint by lifecycle phase
| Phase | Intensity | Share | Main sources of emissions | Notes | Source |
|---|---|---|---|---|---|
| Extraction | low or zero for waste feedstocks | – | residues and tailings enter the system burden-free in most studies | Primary laterite projects in Australia would carry mining burdens | Hengevoss et al. 2024 |
| Refining / processing | about 96% of footprint for Al-Sc2% alloy: acid leaching 63% (energy 38%, sulfuric acid 25%), ion recovery and neutralisation 27%, other steps under 5% each | 96% | electricity, sulfuric acid, CO2 released when neutralising acid with limestone | About 1,800 kg of residue is processed per kg of alloy, with about 25% overall yield | Hengevoss et al. 2024 (Al-Sc2% alloy shares) |
| Movement | negligible per tonne | – | air or courier shipment of kilogram lots | Not material | Qualitative |
| Usage | no direct emissions | – | aerospace alloys, solid oxide fuel cells | Enabling: lighter airframes and efficient fuel cells; reduction to alloy with primary aluminium adds about 4% | Hengevoss et al. 2024; USGS MCS 2026 |
| Recycling / end of life | none: no recycling reported; EU end-of-life recycling input rate 0% | – | scandium is diluted in aluminium scrap | Al-Sc scrap is remelted as aluminium, so the scandium is lost | USGS MCS 2026; EU CRM 2023 |
Other environmental impacts
Large volumes of acid and neutralisation residue per kilogram. Using bauxite residue or titanium wastes as feed can reduce legacy waste stockpiles.
Levers to cut emissions
- Low-carbon electricity at leaching plants (energy is about 38% of the alloy footprint)
- Higher overall yield than the current about 25%
- Recover and reuse acid, and neutralise with low-CO2 alkalis instead of limestone
- Co-recover scandium from existing titanium and nickel HPAL streams rather than new mining
India
India has no scandium production. Its bauxite residue (red mud) from alumina refineries in Odisha and elsewhere is a possible future feedstock, but any plant on India's coal-heavy grid would sit at the high end of the 743-5,500 t CO2e/t range unless supplied with clean power.
Emission figures are indicative global averages from the life-cycle studies named; actual footprints vary widely by site, energy mix and method.