Solid Recovered Fuel (SRF) and Refuse Derived Fuel (RDF)

Solid Recovered Fuel (SRF) and Refuse Derived Fuel (RDF) are types of Waste Derived Fuel, with SRF being distinct from RDF in that its quality as a fuel is far superior.

SRF is typically used in processes that require a high quality, small particle size, high Calorific Value, low Moisture Content material – such as Cement Kilns. RDF typically has more limited processing and shredding in order to provide a uniform fuel to the specification of the end user - such as EfW plants.

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Types of Waste Derived Fuels

The three main types of Waste Derived Fuel are set out below, from the lowest speficiation on the left (RDF) to the highest specification on the right (SRF Pellets). The table below sets out the specification in more detail, but there is no standardisation applied to RDF specifications - they are set by the user under a Fuel Supply Agreement that specifies minimum calorific value, moisture content, the form and the quantity of the RDF.

For the purposes of legislation though, RDF, SRF and SRF Pellets remain waste (unless stringent End of Waste Criteria can be met) and so users of the fuel have to comply with the Industrial Emissions Directive.

RDF

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RDF, at the most basic level, will have had some metals and inert materials removed, removal of some recyclables and limited shredding/bag splitting.[1][2]

SRF

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Solid Recovered Fuels are covered by international technical specifications which set, amongst other parameters, the chemical and physical parameters of an SRF [3].

SRF Pellets

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The development of SRF pellets is an emerging market, typically taking an SRF feedstock and refining it to produce a pellet (typically 6mm, 9mm or 16mm) which has higher Calorific Value, lower moisture and lower ash content.

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SED SED PLACERAT EST
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Phasellus eget mauris 87.40 91.20 93.10
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SED RHONCUS SEM
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Morbi finibus turpis ut EfW EfW EfW
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PRAESENT IN ULLAMCORPER ENIM
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References:

  1. DEFRA Guidance on how to Classify Mechanically Treated Wastes
  2. DEFRA RDF Market in England Respones to Call for Evidence (Dec 2014)
  3. SO/TC 300 Solid Recovered Fuels
  4. WKE Website SRF Fuel Spec
  5. Wastes from mechanical treatment of waste: how to classify (May 2025)
  6. Environment Agency Evidence: Reasons for Trends in English RDF Exports since 2010 (July 2015)
  7. CIWM Presidential Report: RDF Trading in a Modern World (2018)
  8. DEFRA Guidance: Waste Export and Import
  9. Transfrontier Shipment Freedom of Information requested in Q1 2026