What Is Thermal Substitution Rate (TSR)?
Thermal substitution rate (TSR) is the share of cement kiln thermal energy supplied by alternative fuels, on an energy basis. TSR vs AFR explained.
Thermal substitution rate (TSR) is the percentage of a cement kiln's total thermal energy that is supplied by alternative fuels rather than by conventional fossil fuels such as coal and petroleum coke. It is measured on an energy (heat) basis, not a mass basis: a plant burning a mix where alternative fuels deliver 30% of the total heat input has a TSR of 30%, regardless of how many tonnes of each fuel it feeds [1][2]. TSR is the headline metric the cement industry uses to track its shift away from fossil fuel, and it is reported alongside the kiln's specific fuel consumption and emissions.
One disambiguation worth making early: in a cement context TSR always means thermal substitution rate, not total shareholder return (finance) or transfer success rate (telecoms). This piece covers the cement-kiln definition only.
If you are pushing thermal substitution rate up and finding that draft and combustion stability are harder to hold, the kiln seals at the inlet and outlet are often the limiting factor. Our engineering team works through false-air sources case by case, mapping each to a sealing and monitoring fix against your kiln's fuel mix and process profile. Contact us to walk through your configuration.
Sources
- Holcim, *Glossary of Terms (Sustainable Development)*
- Global Cement and Concrete Association, *Co-processing*
- Imubit, *Alternative Fuels in Cement Kilns and AI-Enabled Combustion Control*
- IntechOpen, *Alternative Fuels in Cement Manufacturing*
- Global Cement and Concrete Association, *2050 Net Zero Roadmap: Action and Progress (One Year On)*
- Global Cement, "Cembureau reports increase in alternative fuel usage among its members" (EU27 alternative fuel rate 53% in 2021, 58% in 2022; 2030 target 60%, 2050 target 95%)
- Global CemFuels, *Review of Global CemFuels 2022 Conference & Exhibition*
- Global Cement, "India: industry targets 25% TSR by 2030."
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Contact Engineering Team“Wherever high-temperature rotary kilns operate under controlled atmosphere, Oswal sealing systems ensure energy efficiency and process stability.”