When waste becomes worthwhile


Made from turning landfill into a clean source of energy, solid recovered fuels are a powerful way of reducing carbon emissions and contributing to a greener world.

A growing industry, it involves taking solid wastes, often from our own households, and transforming them into energy for heat and electricity. To help support its expansion in a sustainable way, a series of ISO standards has just been published.

The ISO solid recovered fuel (SRF) series is a collection of nine new standards aimed at providing an agreed terminology, methods and quality levels to facilitate trade and growth in the industry. They cover classifications, test methods, harmonized definitions and terminology, safe handling and more.

With varied terminology across the world, an internationally agreed vocabulary can help promote trade and ensure more effective communication in the industry. ISO 21637, Solid recovered fuels – Vocabulary, provides common terms and definitions that also support the understanding of all the standards in the series.  

Choosing a supplier can be a difficult task, but ISO 21640, Solid recovered fuels – Specifications and classes, can help through defining a means for effectively comparing them. It also sets minimum requirements of what quality is needed to be able to define the fuel as SRF.

With production, handling, transportation and storage of SRF, there is always a significant risk of fire and dust explosion, so it is important that everyone in the supply chain is on the same page. ISO 21912, Solid recovered fuels – Safe handling and storage of solid recovered fuels, provides support, advice and guidance to facility owners, facility designers, logistics providers, equipment suppliers and manufacturers, consultants, authorities and insurance providers to assess and mitigate different risks when producing, handling and storing SRF.

SRF is traded with agreements on the specifications and, to determine those, the material needs to be sampled. ISO 21645, Solid recovered fuels – Methods for sampling, describes the process step by step, reducing any chance of errors.

Other standards in the series include:

  • ISO 21644, Solid recovered fuels – Methods for the determination of biomass content
  • ISO 21656, Solid recovered fuels – Determination of ash content
  • ISO 21660-3, Solid recovered fuels – Determination of moisture content using the oven dry method – Part 3: Moisture in general analysis sample
  • ISO 21663, Solid recovered fuels – Methods for the determination of carbon (C), hydrogen (H), nitrogen (N) and sulphur (S) by the instrumental method
  • ISO 22167, Solid recovered fuels – Determination of content of volatile matter

This series of standards was developed by ISO technical committee ISO/TC 300, Solid recovered materials, including solid recovered fuels, whose secretariat is held by SFS, ISO’s member for Finland. It can be purchased from your national ISO member or the ISO Store.