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CAN/CSA ISO 17225-6-15: Technical Specifications for Graded Non-Woody Pellets
Understanding the Classification, Property Requirements, and Compliance for Solid Non-Woody Biomass Pellets
Scope and Application
CAN/CSA ISO 17225-6-15 is the Canadian adoption of the international standard ISO 17225-6:2015, Solid biofuels — Fuel specifications and classes — Part 6: Graded non-woody pellets. This standard establishes a classification system for pellets produced from non-woody biomass sources such as straw, hay, miscanthus, switchgrass, and other herbaceous materials. It defines both an origin-based classification (classes I1, I2, and I3) and a set of graded property classes for physical and chemical characteristics, enabling transparent trade and consistent fuel quality across producers and end users.
The standard applies to pellets intended for residential, commercial, and industrial combustion devices. It does not cover wood pellets (covered in ISO 17225-2) or briquettes (ISO 17225-3 and ISO 17225-7). The Canadian adoption aligns fully with the 2015 edition of ISO 17225-6 and incorporates the normative references and test methods specified therein.
Tip: CAN/CSA ISO 17225-6-15 is identical to ISO 17225-6:2015, making it suitable for use in domestic and international procurement specifications.
Classification and Property Specifications
Origin-Based Classification
The standard classifies non-woody pellets into three main origin categories, as shown in Table 1. This classification provides a clear indication of the raw material used and serves as the first part of a complete fuel designation.
| Class | Feedstock Description | Typical Examples |
|---|---|---|
| I1 | Whole herbaceous plants without grain | Miscanthus, switchgrass, whole-plant corn (without grain) |
| I2 | Straw from cereals and grasses | Wheat straw, barley straw, rye straw |
| I3 | Other herbaceous and fruit biomass | Olive residues, fruit stones, maize cobs, shelled nut residues |
Property Classes
The standard defines property classes for key fuel parameters, which must be declared together with the origin class. Table 2 summarizes the most significant property classes and their limits. The complete combination classification follows the pattern Origin Class / Moisture Class / Ash Class / Sulfur Class / Nitrogen Class (e.g., I2/M15/A6.0/S0.10/N0.6).
| Property | Class | Limit | Test Method |
|---|---|---|---|
| Moisture (w-% as received) | M10 | ≤ 10 | ISO 18134 |
| M15 | ≤ 15 | ||
| M20 | ≤ 20 | ||
| Ash (w-% dry basis) | A3.0 | ≤ 3.0 | ISO 18122 |
| A6.0 | ≤ 6.0 | ||
| A9.0 | ≤ 9.0 | ||
| Net calorific value (MJ/kg, as received) | Q16 | ≥ 16.5 | ISO 18125 |
| Q15 | ≥ 15.5 | ||
| Q14 | ≥ 14.5 | ||
| Bulk density (kg/m³, as received) | A | ≥ 650 | ISO 18847 |
| B | ≥ 600 | ||
| C | ≥ 550 | ||
| Mechanical durability (w-% as received) | A | ≥ 98.5 | ISO 17831-2 |
| B | ≥ 97.5 | ||
| C | ≥ 95.0 |
The standard also sets limits for sulfur, nitrogen, chlorine, and ash melting behavior, which are selected according to the expected combustion technology. Additional mandatory declarations include dimensions (diameter, length) and fines content.
Caution: Ash contents for non-woody pellets (especially straw-based I2) can reach 8–12 %, significantly higher than wood pellets. Ensure combustion equipment is designed for such fuels to avoid slagging and emission problems.
Sampling and Testing Requirements
CAN/CSA ISO 17225-6-15 requires that all property determinations be carried out using the reference methods listed in the standard. Sampling must follow ISO 18135 (bulk sampling) or be performed using a probative methodology that provides a representative sample of the lot. In Canada, third-party testing laboratories should be accredited to ISO/IEC 17025 for the relevant test methods.
Best Practice: For continuous production control, manufacturers may correlate on-line measurements with reference methods. A regular verification schedule using the full set of required test methods ensures traceability and trust.
Compliance and Certification Notes
When declaring conformity to CAN/CSA ISO 17225-6-15, the complete fuel designation must be used — for example, “I2/M15/A6.0/S0.10/N0.6/A/B/B”. Any tolerance deviations must be stated in the documentation. While the standard itself does not prescribe third-party certification, several certification schemes (e.g., ENplus for non-woody) reference ISO 17225-6, and the Canadian Biomass Pellets Association may offer relevant programs.
For regulators and project developers, compliance with this standard demonstrates that the pellets meet internationally recognized quality criteria, facilitating permitting, financial investment, and cross-border trade. It is essential to note that CAN/CSA ISO 17225-6-15 is a voluntary standard; however, provincial regulations or contract specifications may make adherence mandatory.
Warning: Incomplete or incorrect fuel designation can lead to contractual disputes or regulatory non-compliance. Always specify the full code as outlined in Clause 5 of the standard.
The next revision of this standard (ISO 17225-6:2021) has been adopted in Canada as CAN/CSA ISO 17225-6:21. Users are advised to confirm which edition is referenced in their contractual or regulatory framework. For purposes of this article, the 2015 edition (CAN/CSA ISO 17225-6-15) remains widely used in existing projects and legacy supply agreements.
Article prepared for technical reference; always consult the full standard for complete requirements. ©2026
Frequently Asked Questions
Q: What is the primary difference between wood pellets (ISO 17225-2) and non-woody pellets (ISO 17225-6)?
A: Wood pellets are produced from woody biomass (stemwood, forestry residues), while non-woody pellets come from herbaceous and fruit biomass (straw, grasses, husks). Non-woody pellets typically have higher ash content, different melting behavior, and distinct chemical composition, requiring dedicated combustion equipment.
A: Wood pellets are produced from woody biomass (stemwood, forestry residues), while non-woody pellets come from herbaceous and fruit biomass (straw, grasses, husks). Non-woody pellets typically have higher ash content, different melting behavior, and distinct chemical composition, requiring dedicated combustion equipment.
Q: Can a single lot of pellets be classified under more than one origin class?
A: No. The origin class must correspond to the dominant feedstock. If the fuel is a blend, the manufacturer must declare the blend composition and assign an appropriate origin class based on the major constituent. The standard does not permit combining I1, I2, and I3 classifications in a single designation.
A: No. The origin class must correspond to the dominant feedstock. If the fuel is a blend, the manufacturer must declare the blend composition and assign an appropriate origin class based on the major constituent. The standard does not permit combining I1, I2, and I3 classifications in a single designation.
Q: Is third-party certification mandatory under this standard?
A: No. CAN/CSA ISO 17225-6-15 is a voluntary consensus standard. However, many buyers, regulatory programs, and subsidy schemes require verification of compliance by an accredited body, making certification practically essential for market access.
A: No. CAN/CSA ISO 17225-6-15 is a voluntary consensus standard. However, many buyers, regulatory programs, and subsidy schemes require verification of compliance by an accredited body, making certification practically essential for market access.
Q: Does the standard require testing of every production batch?
A: The standard outlines a minimum testing frequency that depends on the parameter and production scale. For example, moisture content may be checked continuously on-line, while full property analysis (ash, sulfur, calorific value) should be performed at least once per production shift and whenever feedstock changes. Lot-based sampling and analysis is recommended for trade.
A: The standard outlines a minimum testing frequency that depends on the parameter and production scale. For example, moisture content may be checked continuously on-line, while full property analysis (ash, sulfur, calorific value) should be performed at least once per production shift and whenever feedstock changes. Lot-based sampling and analysis is recommended for trade.
Reminder: This article is based on the 2015 edition. For current projects, verify whether the 2021 edition applies.