ISO 17225-8:2023

Overview

ISO 17225-8:2023 - "Solid biofuels - Fuel specifications and classes - Part 8" defines fuel quality classes and specifications for graded thermally treated and densified biomass fuels (pellets and briquettes) intended for commercial and industrial use. The standard covers fuels produced from woody, herbaceous, fruit, aquatic biomass and blends, specifies how properties are declared (including energy-related units), and provides templates and reference values to support consistent product specification and trading. Charcoal products are excluded (see ISO 17225‑1:2021).

Key topics and requirements

• Scope of materials: Pellets and briquettes from thermally treated biomass (e.g., torrefaction, steam explosion, hydrothermal carbonization, charring).
• Fuel classes and properties: Normative property classes for mechanical, physical and chemical parameters are given in Tables 1–3; ash and element concentrations are declared in energy units (g/MJ or mg/MJ, dry basis).
• Mandatory analyses and sampling: Sampling and sample prep according to ISO 18135 / ISO 21945 and ISO 14780; analytical methods referenced for moisture, calorific value, ash, elemental analysis, durability, fines, bulk density, dimensions (see Normative references).
• Declaration and traceability: Producers/suppliers must state the quality class at delivery and include both energy-based and mass-based values (e.g., mg/kg dry). Distributors must maintain fines levels during transport.
• Specification tools: Annex A provides a template for product specification; Annex B supplies reference values for converting limits to energy-based units.
• Safety note: Health, safety and environmental aspects are acknowledged as important but are outside the document’s technical scope.

Practical applications and users

ISO 17225-8:2023 is intended for:

• Fuel producers and densification plants producing thermally treated pellets/briquettes.
• Commercial and industrial energy users (boilers, furnaces) and equipment manufacturers who require classified fuel quality.
• Traders, distributors and buyers who need standardized quality classes for procurement and contracts.
• Testing laboratories and conformity assessors performing sampling and analyses according to referenced ISO methods.
  Practical benefits include clearer contracts, improved market transparency, easier communication with equipment manufacturers, and support for permitting and reporting.

Related standards

Key supporting standards referenced:

• ISO 17225-1:2021 (general requirements and charcoal specification)
• ISO 18125 (calorific value), ISO 18134-1/2 (moisture), ISO 18122 (ash content)
• ISO 17831-1/2 (mechanical durability), ISO 5370 (fines content)
• ISO 16948, ISO 16968, ISO 16994 (elemental analyses)
• ISO 17828, ISO 17829 (bulk density, pellet dimensions), ISO 18135 / ISO 21945 (sampling)

Keywords: ISO 17225-8:2023, solid biofuels, thermally treated biomass, pellets, briquettes, fuel specifications, densified biomass, commercial and industrial use.