Abrasives: Emissions
Why each tonne of silicon carbide costs over 4 t 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 4.20 t CO2e per t range 4.2-6.5 (higher on coal-heavy grids, derived) · cradle-to-gate furnace emissions: about 2.4 t CO2 from carbothermic reduction plus 1.8 t from 7.15 MWh of electricity; raw material supply excluded Global emissions per year 5.00 Mt CO2e per year 2025 · if the 1.0 Mt of world capacity ran fully at 4.2-6.5 t/t, about 4-6.5 Mt; actual output not published (derived, indicative)Per t of crude silicon carbide from an Acheson furnace, cradle-to-gate (fused alumina noted separately). Intensity: Fraunhofer IKTS, RECOSiC press release, June 2023 (indicative); upper end derived with China grid about 0.57 t CO2/MWh (MEE, indicative). Global total: USGS MCS 2026; Fraunhofer IKTS 2023.
Share of footprint by lifecycle phase
Refining / processing 100%Footprint by lifecycle phase
| Phase | Intensity | Share | Main sources of emissions | Notes | Source |
|---|---|---|---|---|---|
| Extraction | not included; silica sand and petroleum coke are by-products or bulk materials | – | quarrying sand; petcoke comes from oil refining | small relative to furnace emissions | MPA 2009 (sand analogue) |
| Refining / processing | about 4.2 t CO2e/t | 100% | SiO2 + 3C to SiC + 2CO: about 2.4 t CO2 per t once CO is burned; about 7.15 MWh/t of electricity (European plants 6.3-9.0 MWh/t) | process CO2 from carbon cannot be avoided by clean power; fused alumina instead uses electric arc furnaces and its intensity was not found in published sources | Fraunhofer IKTS 2023; Mehrwald 1992 via Redalyc |
| Movement | about 70 kg CO2e/t per 10,000 km by bulk ship (derived) | – | crude grain shipped from China to grain finishers worldwide | large bulk ship about 0.007 kg CO2e per t-km, road truck 0.178 (ERM for The Crown Estate, 2010) | ERM for The Crown Estate, 2010 (derived) |
| Usage | no direct emissions from the grain; grinding machines use electricity | – | wheels, belts and blast media are consumed in manufacturing | silicon carbide in power electronics cuts losses in EVs and grids, but that is a different, high-purity product | USGS MCS 2026 |
| Recycling / end of life | recycled SiC needs about 80% less energy than the Acheson process | – | up to 30% of fused alumina and about 5% of silicon carbide may be recycled; steel shot is reused many times | Fraunhofer's RECOSiC recovers SiC at nearly 100% yield | Fraunhofer IKTS 2023; USGS MCS 2026 |
Other environmental impacts
Acheson furnaces emit carbon monoxide and sulfur compounds from petroleum coke. Brown fused alumina furnaces emit dust and fluorides.
Levers to cut emissions
- Run furnaces on low-carbon power: Norway's hydro-based plants avoid most of the 1.8-4.1 t of electricity-related CO2 per t (derived)
- Recycle spent SiC with processes such as RECOSiC that cut energy about 80% (Fraunhofer IKTS 2023)
- Raise fused alumina recycling toward the 30% USGS cites as possible
- Use bio-based carbon reductants in place of petroleum coke to address the 2.4 t of process CO2 per t (research stage)
India
India has 40,000 t of fused alumina and 5,000 t of silicon carbide capacity (USGS 2026). On a grid of about 0.72 t CO2/MWh (CEA 2024, indicative), Acheson silicon carbide would emit about 7.5 t CO2 per t (2.4 t process plus 7.15 MWh x 0.72, derived).
Emission figures are indicative global averages from the life-cycle studies named; actual footprints vary widely by site, energy mix and method.