Improving the quality of SRF/RDF

Written by: Chris Rixson | Published:

The industry must maximise opportunities where RDF and SRF can become a more sustainable fuel source, according to Dr Stephen Wise, waste sector director and waste technical leader at Wood Plc.

Refuse-derived fuel (RDF) and solid recovered fuel (SRF) coupled with Energy from Waste (EfW) is a key method for taking the residual element of both municipal and commercial waste and converting it for further beneficial use as a form of energy. It is a key part of both the traditional linear and circular economy and is low cost, secure and sustainable.

Julio Garcia Burges, head of waste division at DG Environment said in February 2015 that: “the future holds a place for WtE (waste to energy) solutions…the experience in better performing (EU) member states shows that high recycling rates above 60% can co-exist with waste to energy levels approaching 30% if recyclable and recoverable materials are diverted from landfill.”

The development of RDF and SRF market

RDF and SRF are generic terms used within the waste management and resource sector to describe fuel that has been manufactured from ‘processing’ either municipal or commercial waste. Processing is undertaken through a combination of mechanical and biological treatments such as shredding and drying. SRF has been defined to a much stricter set of parameters and for which end users have much stricter requirements such as Calorific Value (CV) Moisture Content (MC%) and Chlorine (Cl).

To achieve the European definition for SRF, most waste material is required to undergo extensive mechanical and / or biological processing to meet the stricter parameters. However, for RDF there is no single definition through a common standard or processing requirements. This approach has been supported by the broad definition applied after DEFRA completed their consultation with respect to RDF.

A lack of single standard across the broader RDF market means that it is relatively easy for operators to produce an RDF with minimal processing and investment, which has led to a dramatic rise in the production of RDF within the UK.

Increased production coupled with a lack of standards has seen an increase in environmental issues through associated supply chain activities including storage and transportation. Problems include the failure to extract recyclables such as ferrous metals, unsuitable wrapping leading to odours and flies and an increased fire hazard. Therefore, any additional control on the quality of RDF also needs to take into account these downstream activities to ensure that best practice is achieved throughout the supply chain.

Shake up

The UK waste market is estimated to be worth approximately £10.5bn per year, according to the Office of National Statistics (ONS). Until relatively recently it has been dominated by the letting of Private Finance Initiative (PFI) and Private Public Partnership (PPP) contracts by local authorities for the collection, treatment and disposal of municipal waste.

These contracts were supported with funding from central government and resulted in the construction of large waste treatment facilities across the UK. This has included the construction of mechanical and biological treatment (MBT) facilities in various configurations and EfW plants to both produce and make use of RDF and SRF. The majority of the RDF and SRF produced under these long-term contracts is used for energy generation within the UK market yet a proportion has been sent overseas.

Funding was withdrawn from PFI and PPP contracts for the waste collection, treatment and disposal as the government believed there was sufficient municipal waste treatment capacity within the UK to meet the 2020 landfill diversion target set by Europe.

With the market for the development of new treatment infrastructure for the municipal sector stalling and the continued increase in landfill tax (as from April 1, 2016 it was £84.40 per tonne) there has been an increased focus on providing additional capacity to treat commercial and industrial (C&I) waste which has resulted in an increase in the number of merchant facilities being proposed, many of which focus on the production of RDF.

The increase in RDF production combined with both a shortfall in capacity at EfW plants within the UK and a strong pound led to the development of the export market. Initially this resulted in RDF being sent to countries such as the Netherlands and Germany but has grown to see exports to Sweden, Eastern Europe and beyond.

It had been widely expected that the export market would continue to grow beyond 2016 and until new EfW’s in the UK commenced operation. The failure of high profile projects such as the Air Products advanced EfW at Tees Valley has placed further pressure on the export market.

However, Britain’s decision to leave the European Union has changed this outlook. The immediate impact has not been a consequence of a change in relations with EU countries, but the resulting devaluation of the pound, which has placed significant pressure on those exporting RDF and SRF into the European market. A number of organisations are now struggling to viably export RDF and SRF with a some going into administration and more expected to follow suit.

Tackling poor quality

As the production of RDF has grown, perhaps a more successful way of tackling poor quality is to look at the whole supply chain and include production, storage and transportation. This would then provide a focus on other existing regulations such as waste crime under which storage and transportation is covered.

Requiring more stringent permitting or some form of financial guarantee or bond would also assist in improving the standards within the whole supply chain, reduce impact on the environment from issues such as odour and may help to prevent the rogue operators from entering the market and reduce the associated ‘grey market’.

The designation of incineration as recovery means that waste can cross borders. Although not legally binding, European guidance on this allows for the heat used within the plant to be counted when assessing whether a plant qualifies for recovery or disposal meaning that R1 status can be achieved through electricity generation.

Perhaps an alternative, more challenging, threshold based on the amount of heat and power exported and utilised would give greater confidence that where residual waste as RDF is exported for recovery the efficiency of the energy recovery and used would be higher.

Long-term goals

The treatment of municipal and commercial waste to produce RDF is here to stay. However, we are likely to see in the long term more RDF used within the UK market as additional Energy from Waste capacity becomes available.

Including EfW as part of the circular economy, and not as an afterthought or bolt on, will ensure that the correct focus is placed on generating quality recycling whilst ensuring the most effective use of the residual as a fuel for energy generation. It can act as a driver for quality recycling by providing a valuable method for the treatment of contaminated or non-suitable waste and by keeping harmful materials out of the recycling supply chain.

The RDF sector must look to identify, embrace and maximise opportunities where RDF can become a more sustainable fuel source to support manufacturing and power generation. However, to do this the sector must recognise that RDF should be produced in a manner which prevents harm to the environment throughout the supply chain- from production to storage and transportation.

Want to hear more from Dr Wise? He will be chairing a panel discussion on Syngas pre- and post-accreditation in gasification at the Energy from Waste Conference, taking place at etc.venues County Hall, London on 28 February – 1 March. For more information, visit

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