---
title: "Thermal substitution rate (TSR)"
description: "Thermal substitution rate (TSR) is the percentage of total kiln energy input supplied by alternative fuels rather than fossil fuel (coal, petcoke, gas, oil). TSR is the headline AFR-adoption metric tracked by the cement industry and is central to every cement-major decarbonisation roadmap."
canonical_url: "https://sylio.co/glossary/thermal-substitution-rate"
last_updated: "2026-06-28T02:29:27.885Z"
---

**Thermal substitution rate (TSR)** is the percentage of total kiln energy input supplied by [alternative fuels](/glossary/alternative-fuel) rather than fossil fuel (coal, petcoke, gas, oil). TSR is the headline AFR-adoption metric tracked by the cement industry and is central to every cement-major decarbonisation roadmap.

## Typical TSR ranges by region (2025)

<table>
<thead>
  <tr>
    <th>
      Region
    </th>
    
    <th>
      Average TSR
    </th>
  </tr>
</thead>

<tbody>
  <tr>
    <td>
      Northern Europe (DE, NL, AT)
    </td>
    
    <td>
      60–80%
    </td>
  </tr>
  
  <tr>
    <td>
      Western Europe (FR, UK, IT, ES)
    </td>
    
    <td>
      40–60%
    </td>
  </tr>
  
  <tr>
    <td>
      Southern Europe (GR, PT)
    </td>
    
    <td>
      25–40%
    </td>
  </tr>
  
  <tr>
    <td>
      North America
    </td>
    
    <td>
      15–25%
    </td>
  </tr>
  
  <tr>
    <td>
      China
    </td>
    
    <td>
      5–10%
    </td>
  </tr>
  
  <tr>
    <td>
      India
    </td>
    
    <td>
      10–20%
    </td>
  </tr>
  
  <tr>
    <td>
      Brazil / LATAM
    </td>
    
    <td>
      20–35%
    </td>
  </tr>
</tbody>
</table>

Several European plants now exceed 90% TSR; the technical and procurement frontier sits beyond 95%.

## Why higher TSR drives sonic-horn demand

Each step up in TSR raises the chlorine, sulphur and alkali loading reaching the [preheater tower](/glossary/preheater-tower) — see [sulphur and chloride cycles](/glossary/sulphur-cycle-chloride-cycle-alkali-cycle). This intensifies coating, build-up and pluggage in the preheater, calciner and [kiln-inlet](/glossary/kiln-inlet-riser-duct), increasing the frequency and severity of cleaning interventions. [Sonic horns](/glossary/sonic-horn) become more valuable — and often more numerous — as TSR rises.

## Related terms

- [Alternative fuel (AFR)](/glossary/alternative-fuel)
- [RDF / SRF / TDF](/glossary/rdf-srf-tdf)
- [Sulphur / chloride / alkali cycles](/glossary/sulphur-cycle-chloride-cycle-alkali-cycle)
- [Chloride bypass](/glossary/chloride-bypass)