Solid Recovered Fuel (SRF) is a type of Waste Derived Fuel but is distinct from Refuse Derived Fuel (RDF) in that its quality as a fuel is far superior. It is typically used in processes that require a high quality, small particle size, high Calorific Value, low Moisture Content material – such as Cement Kilns and new-generation ATT plants. There is a move in the UK towards the production of pellets from SRF for subsequent use in industrial processes.

Picture of loose SRF, source Geminor all rights reserved
Picture of loose SRF, source Geminor all rights reserved


Context

Solid Recovered Fuel (SRF) is a type of Waste Derived Fuel but is distinct from Refuse Derived Fuel (RDF) in that its quality as a fuel is far superior. It is typically used in processes that require a high quality, small particle size, high Calorific Value, low Moisture Content material – such as Cement Kilns and new-generation ATT plants. There is a move in the UK towards the production of pellets from SRF for subsequent use in industrial processes.

Data for Cement Kilns in UK suggests that around 400,000 tonnes of SRF was used as a WDF in 2019 and 2020.

Solid Recovered Fuels are covered by international technical specifications which set, amongst other parameters, the chemical and physical parameters of an SRF [1]. For the purposes of legislation, though, SRF remains a waste (unless stringent End of Waste Criteria can be met) and so users of the fuel have to comply with the IED which has superseded WID.

Composition of Solid Recovered Fuel

The composition of SRF is defined in the international specification set out above, but often an SRF in the UK can be a more refined RDF rather than something that complies entirely with the specification standard. The main chemical parameters that vary between an RDF and SRF are Calorific Value and Moisture Content, and the table below shows a comparison between RDF and SRF based upon a range of specification sheets for illustration.

Measure Units RDF SRF
Net Calorific Value MJ/kg (as received) 10 - 15 >18.5
Moisture wt% (dry basis) <25 <15
Biomass Content[2] wt% (dry basis) >65 >65
Ash Content wt% (dry basis) <20 <15
Sulphur wt% (dry basis) <0.5 <0.5
Nitrogen wt% (dry basis) <0.8 <0.8
Lead mg/kg <100 <80
Chlorine CI wt% (dry basis) <0.1 <0.6
Zinc[3] wt% (dry basis)    
Sodium and Potassium[3] wt% (dry basis)    
Mercury mg/kg <1 <0.6
Nickel mg/kg <100 <100
Thallium mg/kg <10 <10
Ferrous and non-ferrous metals wt% (dry basis) <3 <1
Non combustible material wt% (dry basis) <10 <5
Glass wt% (dry basis) <2 <1
Dust <1mm wt% (dry basis) <5 <5
Bulk Density (loose) kg/m3 100 - 175 185
Particle Size (max dimension) mm 300 <40

Chlorine is a particular issue due to its tendency to form Hydrochloric Acid in an energy recovery process, which then requires specific abatement/clean-up technologies. With limited such arrangements in Cement Kilns this means that they generally have a lower tolerance for Chlorine closer in spec to an SRF. In addition, the use of any Waste Derived Fuel in Cement Kilns has the potential to impact the final quality of the cement produced, and so the composition is critical in the decision to use it in such an application in terms of the ash content of the SRF fuel.

Background to Export of Refuse Derived Fuel and Solid Recovered Fuel

The movement of WDF from the UK, primarily in the EU, commenced in c.2010 and progressively grew up until around 2016 driven by supply-demand and landfill tax in the UK and the economics and spare capacity of EfW plants in the EU. From around 2017 tonnages for export started to drop, with more pronounced drops from 2018 as the supply-demand patterns changed in the UK, some EU countries started to implement taxation on EfW and the cost and complexities of transportation following Brexit increased. The two charts below show the overall patterns of export and whilst the data clearly shows the drop in RDF tonnage, the tonnage of SRF shows a more stable export position from 2018 of around 400,000 tonnes a year.

 
CIWM Presidential Report 2018 – RDF Trading in a Modern World
 
RDF and SRF Export - analysis of EA data by Monksleigh
CIWM Presidential Report (2018) Showing Grow in RDF and SRF Export[4] Analysis by Monksleigh of RDF and SRF Exports from England from EA Data

Moving Refuse Derived Fuel and Solid Recovered Fuel from the UK abroad requires compliance with the Transfrontier Shipment Regulations (TFS) and in simple terms requires an application for movement to be made to the relevant authorities that requires a number of key measures to be satisfied before this can occur. It also requires the user of the fuel to be classified as an R1 facility.

Annual SRF Export from England

The data shown is for export from England and for Waste Code 19 12 10 - combustible waste (refuse derived fuel) as this is the primary code that covers both RDF and SRF tonnage.

It is important to note that some RDF / SRF is exported under the Waste Code 19 12 12 - other wastes (including mixtures of materials) from mechanical treatment of wastes other than those mentioned in 19 12 11, this code is a catch all, and covers any waste from Mechanical treatment not covered by it's own 19 12 waste code and as such has not been included in the numbers below.

The data included here is taken from the Waste Description as shown on the Transfrontier Shipment notice, which describes the waste as RDF or SRF.

Month on Month Export

The graph shows the monthly shipments of SRF along with a trend line showing the trajectory of export for 2015 onwards.

 

Year on Year Differences

The year on year export of SRF from England 2015 onwards.

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Data Table
Year Tonnage Shipped Increase on Previous Percentage Change
2015 65,408 - -
2016 100,521 35,112 53.7%
2017 239,827 139,306 138.6%
2018 379,866 140,039 58.4%
2019 377,556 -2,310 -0.6%
2020 371,063 -6,493 -1.7%
2021 470,732 99,669 26.9%
2022 301,987 -168,745 -35.8%

Exporters

The notifiers of Export of SRF from 2015 onwards.


Company 2015 2016 2017 2018 2019 2020 2021 2022

ABN Paris SAS 0.00 0.00 0.00 2,243.85 0.00 0.00 0.00 0.00
Andusia Recovered Fuels Ltd 0.00 0.00 0.00 2,282.30 7,700.90 5,507.17 3,374.70 7,397.89
Bertling Enviro AB 0.00 0.00 0.00 2,660.62 12,617.16 9,763.73 21,316.80 12,837.15
Camreg Ltd 0.00 18,615.41 26,170.11 21,182.62 0.00 11,978.86 0.00 5,542.46
Eco-Power Environmental (Hull) Ltd 0.00 0.00 0.00 0.00 3,658.50 39,618.29 52,642.37 14,443.64
Enva England Ltd 0.00 0.00 0.00 0.00 0.00 49.02 3,600.56 1,220.15
Geminor UK Ltd 0.00 0.00 0.00 19,097.16 16,281.96 6,213.17 4,411.87 2,422.17
Mid UK Recycling Ltd 0.00 0.00 14,932.59 52,481.18 21,887.32 0.00 0.00 0.00
N & P Alternative Fuels Ltd 1,599.04 20,085.86 47,574.67 195,381.42 182,327.92 138,389.92 123,036.19 128,466.25
New Earth Solutions (West) Ltd T/A Mid UK Recycling 0.00 0.00 0.00 0.00 18,345.31 77,417.63 63,541.92 44,964.17
Pericula Ltd 0.00 0.00 288.59 1,199.70 3,793.76 0.00 0.00 0.00
PM Recycling Ltd 0.00 0.00 7,554.97 0.00 0.00 0.00 0.00 0.00
Probio Energy Ltd 0.00 3,009.58 12,931.00 45,134.08 91,809.27 93,617.45 82,937.86 64,813.10
Quercia Ltd 0.00 21,373.09 54,156.17 32,629.36 26,004.50 58,498.90 54,419.39 0.00
Seneca Environmental Solutions Ltd 0.00 0.00 0.00 0.00 2,506.14 0.00 0.00 0.00
Shanks Waste Management Ltd 16,961.94 2,774.31 0.00 0.00 0.00 0.00 0.00 0.00
Specialised Waste Solutions Ltd 0.00 0.00 0.00 48.54 169.88 0.00 0.00 0.00
Street Fuel Ltd 0.00 0.00 2,884.98 2,046.49 0.00 0.00 0.00 0.00
SUEZ Recycling and Recovery UK Ltd 34,204.07 31,629.53 90,294.92 231.64 0.00 0.00 0.00 0.00
Totus Environmental Ltd 0.00 3,033.00 2,854.83 9,471.75 302.60 118.56 2,656.44 2,524.51
Transwaste Recycling & Aggregates Ltd 12,643.31 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Nascent SRF Pellet Market

Increasingly the market is considering further refinement (including reducing moisture and increasing NCV) of SRF to produce a high quality fuel pellet for ease of storage, haulage, and introduction into a Cement Kiln, with some companies seeking to achieve End of Waste Criteria classification that would then enable the material to be used in other applications as a blended substitute for coal. There are three main organisations pursuing this approach in the UK market at the present time, each with a different 'brand name' for their pellet:

N+P (Subcoal®)

N+P have been producing a pellet in their operation in the Netherlands and are in the process of producing their Subcoal®[5] pellets in their first plant in the UK in Teeside, with plans to expand to this at their recently acquired facility at Crayford[6]

Waste Knot (SIRF Pellets)

Waste Knot's SIRF pellet[7] is to be produced in their first plant, which is under construction in Middlesborough[8]

Eco-PowerFuels (Eco Power Pellets)

Eco-PowerFuels have been producing their Eco-Power Pellets in their facility in Humberside[9] and in January 2021 was reported to have signed a contract to supply Tarmac's Tunstead Cement Kiln[10]

References

  1. [1] ISO/TC 300 Solid Recovered Fuels
  2. Not generally defined for exports to EU (no biomass requirements.)
  3. 3.0 3.1 Not generally defined in a fuel spec
  4. CIWM Presidential Report 2018 Summary of Findings pdf
  5. N+P website
  6. N+P Press Release January 2022
  7. Waste Knot SIRF Web page
  8. Waste Knot Website News Page
  9. Eco-PowerFuels Website
  10. News Article from World Cement