The fair comparison is energy-based
Thermal substitution rate expresses how much of the kiln’s thermal energy comes from alternative fuels. It is more informative than tonnes of RDF divided by tonnes of coal because the materials can have different energy values and moisture contents.
A credible comparison defines the baseline conventional fuel, measurement period and energy basis before reporting substitution.
When can RDF reduce fossil CO₂?
RDF contains a mixture of carbon sources. Its fossil fraction remains part of the fossil CO₂ account. A verified biogenic fraction may receive different treatment under the applicable accounting rules, subject to the required measurement and sustainability conditions.
Therefore, a defensible claim is conditional: RDF may reduce fossil CO₂ when it displaces coal energy and has a verified biogenic fraction. The result must be calculated for the actual material and plant basis. RDF is not automatically low-carbon, carbon neutral or zero-emission.
Operational fit still decides the route
Coal is generally more uniform. RDF can introduce wider variation in calorific value, moisture, chlorine, ash, metals and particle size. Preparation, representative sampling, blending and incoming control are needed to protect feed stability, clinker chemistry and permit compliance.