Glossary
Cement
RDF, SRF and TDF
Also known as refuse-derived fuel, solid recovered fuel, tyre-derived fuel, RDF, SRF, TDF.
RDF, SRF and TDF are the three dominant waste-derived alternative fuels used in cement kilns, waste-to-energy plants and industrial boilers.
| Fuel | Source | Specification | Calorific value |
|---|---|---|---|
| RDF (Refuse-Derived Fuel) | Municipal solid waste, lightly processed | Loose, no formal CEN/TS specification | 12–18 MJ/kg |
| SRF (Solid Recovered Fuel) | MSW + commercial waste, processed to CEN/TS 15359 spec | Defined particle size, ash content, calorific value, Cl, Hg | 15–20 MJ/kg |
| TDF (Tyre-Derived Fuel) | End-of-life tyres, shredded | Shred-size grade or whole-tyre | 28–35 MJ/kg |
Trade-offs
- RDF: cheap, high availability, variable composition; high chlorine swings
- SRF: more consistent and predictable than RDF; commands premium gate fees
- TDF: very high calorific value, supplies iron and sulphur to clinker chemistry; rubber-handling logistics
Fouling implications
All three add chlorine, sulphur and alkali metals beyond what fossil coal contributes. The chloride loading from chlorinated plastics in RDF / SRF is the dominant driver of chloride-bypass sizing. TDF adds zinc and iron oxides that can affect clinker chemistry.
Related terms
Related terms
- Alternative fuelAlternative fuels (AFR) replace fossil fuel in cement kilns. They cut CO2 emissions and waste-disposal cost but increase chlorine, sulphur and alkali loading in the kiln gas.
- Thermal substitution rateTSR is the percentage of total kiln-energy input supplied by alternative fuels rather than fossil fuel. The headline AFR adoption metric for cement-industry decarbonisation.
- Waste-to-energyWtE plants burn municipal solid waste, RDF, SRF and biomass to generate steam and electricity. Sticky chloride-rich ash defeats conventional cleaning; sonic horns are the dominant fit.