A number of countries have established their own standards; however in Europe there is an attempt to consolidate the regulatory environment for biomass pellets under the European Committee for Standardization.
American Standards
The solid fuel standards that exist in the United States are determined by the Pellet Fuel Institute (PFI). Compliance is voluntary. The table below lists the specifications for pellets across three classes: premium, standard and utility.
| Fuel Property | Premium | Standard | Utility |
| Bulk density (lb/ft3) | 40.0-46.0 | 38.0-46.0 | 38.0-46.0 |
| Diameter (in) | 0.230-0.285 | 0.230-0.285 | 0.230-0.285 |
| Diameter (mm) | 5.84-7.25 | 5.84-7.25 | 5.84-7.25 |
| Pellet durability index (PDI) | >96.5 | >95.0 | >95.0 |
| Percent fines (at mill gate) | <0.50 | <1.0 | <1.0 |
| Inorganic ash (%) | <1.0 | <2.0 | <6.0 |
| Length (% greater than 1.5 in) | <1.0 | <1.0 | <1.0 |
| Moisture (%) | <8.0 | <10.0 | <10.0 |
| Chloride (ppm) | <300 | <300 | <300 |
Table 1: US Pellet Fuel Institute biofuel standards
European Common Standard (CEN)
The combined standards from various European countries such as Austria, Sweden, the United Kingdom, France and Denmark are known as the European Common Standard for Solid Fuel (CEN). The European Committee for Standardization (CEN/TC 335) has prepared technical specifications and testing methods for solid biofuels. CEN/TS 14961 gives the standards for the densified solid fuels like pellets and briquettes. Below lists the individual standards for solid fuels followed by different countries such as Austria, Sweden, the United Kingdom, France, and Denmark, although these individual standards have been replaced with a common standard called the European Common Standard for Solid Fuel (CEN).
Common European solid biofuels standards were established to avoid ambiguity; previously, many European countries had their own standards. The European Committee for Standardization (CEN/TC 335) prepared technical specifications and testing methods for solid biofuels. The following are some of the standards developed for classifying properties of solid biofuels based on CEN:
- Classification of biomass based on Based on CEN/TS 14961, the biomass is classified based on its origin and divided into these subcategories: woody, herbaceous, fruit, and blends and mixtures.
- Major traded forms of solid
- Technical specifications for pellets and briquettes according to
| CEN/TS 14961:2004 | Applies to: 1) Woody biomass, 2) herbaceous biomass, 3) fruit biomass, 4) blends and mixtures |
| Traded Form | Pellets |
| Normative specifications | |
| Dimensions (mm) Diameter and length (L)a | D06 ≤ 6mm ± 0,5 mm and L ≤ 5 × Diameter D08 ≤ 8 mm ± 0,5 mm and L ≤ 4 × Diameter D10 ≤ 10 mm ± 0,5 mm and L ≤ 4 × Diameter D12 ≤ 12 mm ± 1 mm and L ≤ 4 × Diameter D25 ≤ 25 mm ± 1 mm and L ≤ 4 × Diameter |
| Moisture (w-% as received) | M10 ≤ 10%M15 ≤ 15%M20 ≤ 20% |
| Ash (w-% of dry basis) | A0.7 ≤ 0.7%A1.5 ≤ 1.5%A3.0 ≤ 3.0%A6.0 ≤ 6.0% |
| A6.0+ > 6.0% (actual value to be stated) | |
| Sulfur (w-% of dry basis)b | S0.05 ≤ 0.05%S0.08 ≤ 0.08%S0.10 ≤ 0.10%S0.20+ > 0.20% (actual value to be stated) |
| Mechanical durability (w-% of pellets after testing) | DU97.5 ≥ 97.5DU95.0 ≥ 95.0DU90.0 ≥ 90.0 |
| Amount of fines (w-% <3.15 mm)c | F1.0 ≤ 1.0%F2.0 ≤ 2.0%F2.0+ > 2.0% (actual value to be stated) |
| Additives (w-% of pressing mass) | Type and content of pressing aids, slagging inhibitors or any other additives have to be stated |
| Nitrogen (w-% of dry basis) | N0.3 ≤ 0.3%N0.5 ≤ 0.5%N1.0 ≤ 1.0%N3.0 ≤ 3.0%N3.0+ > 3.0% (actual value to be stated) |
| Informative specifications | |
| Net caloric value (MJ/kg as received) or energy density (kWh/m³ loose) | Recommended to be informed by retailer |
| Bulk density as received (kg/m³ loose) | Recommended to be stated if traded by volume basis |
| Chlorine, Cl (weight of dry basis w-%) | Recommended to be stated in category Cl 0.03, Cl 0.07, Cl 0.10, and Cl 0.10+ (if Cl >0.10% the actual value to be stated) |
| a. Maximum 20 w-% of the pellets may have a length of 7. 5 diameter.b. Sulfur is normative only for chemically treated biomass and if sulfur-containing additives have been used.c. After production at factory gate, at last possible place in the production site. | |
Austria
The Austrian Federal Ministry for the Environment devised a special environment label for biomass fuels. Only raw material from natural wood is allowed (sawdust, shavings, etc.). Use of materials such as packaging, coatings, glues, chipboard, or fiberboard residues is forbidden. Chemical parameters, testing methods, and limit values are similar to those in ÖNORM 7135.
| Specification | Austria ÖNORM M7135 | |
| Holzpresslinge | Rindenpresslinge | |
| Pellets | Briketts | |
| Size | 4-20 mm dia.Max 100 mm length | 20-120 mm dia. Max 400 mm length |
| Bulk density | ||
| Fines %<3 mm | ||
| Unit density | ≥ 1.0 kg/dm3 | ≥ 1.0 kg/dm³ |
| Moisture content | ≤ 12% | ≤ 18% |
| Ash content | ≤ 0.5% | ≤ 6.0% |
| Caloric value | ≥ 18.0 MJ/kg | ≥18.0 MJ/kg |
| Sulfur | ≤ 0.04% | ≤ 0.08% |
| Nitrogen | ≤ 0.3% | ≤ 0.6% |
| Chlorine | ≤ 0.02% | ≤ 0.04% |
| Arsenic | ||
| Cadmium | ||
| Chromium | ||
| Copper | ||
| Mercury | ||
| Lead | ||
| Zinc | ||
| EOX: extractable halogens |
Table 2: Austria ÖNORM M7135 pellet standards
Sweden
Pellsam, the Swedish wood pellet trade body, was set up by manufacturers and suppliers of pellet heating equipment to establish standards for wood pellets for heating purposes.
| Specification | Sweden SS 18 71 20 | ||
| Group 1 | Group 2 | Group 3 | |
| Size | Max 4 mm dia. | Max 5 mm dia. | Max 6 mm dia. |
| Bulk density | ≥ 600 kg/m³ | ≥500 kg/m³ | ≥500 kg/m³ |
| Fines %<3 mm | ≤ 0.8 | ≤1.5 | ≤1.5 |
| Unit density | |||
| Moisture content | ≤ 10% | ≤10% | ≤12% |
| Ash content | ≤ 0.7% | ≤1.5% | >1.5% |
| Caloric value | ≥ 16.9 MJ/kg≥ 4.7 kWh/kg | ≥16.9 MJ/kg≥4,7 kWh/kg | ≥16.9 MJ/kg≥4.7 kWh/kg |
| Sulfur | ≤ 0.08% | ≤0.08% | anges |
| Nitrogen | |||
| Chlorine | ≤ 0.03% | ≤0.03% | anges |
| Arsenic | |||
| Cadmium | |||
| Chromium | |||
| Copper | |||
| Mercury | |||
| Lead | |||
| Zinc | |||
| EOX: extractable halogens | |||
Table 3: Sweden SS 18 71 20 pellet standards
United Kingdom
The United Kingdom (UK) pellet market started with a project to introduce wood pellets to the UK with the Department of Trade and Industry (DTI). In the framework of this project, British BioGen have produced codes of good practice for biofuel pellets and pellet-burning room heaters <15 kW. The codes of good practice were developed as an interim measure and will be superseded by the European Standards for Solid Biofuels once they are published.
| Specification | British BioGen/UK Code of Good Practice | |
| Size | <4 mm–20 mm | >10 mm–<20 mm |
| Bulk density | >600 kg/m³ | >500 kg/m³ |
| Fines %<3 mm | <0.5% | <0.5% |
| Unit density | >40 pounds/cubic ft. | |
| Moisture content | ≤10% | ≤10% |
| Ash content | < 1%, <3% or 6 | <1%, <3% or 6 |
| Caloric value | >4.7 kWh/kg | >4.2 kWh/kg |
| Sulfur | <300 ppm | <300 ppm |
| Nitrogen | ||
| Chlorine | <800 ppm | <800 ppm |
| Arsenic | ||
| Cadmium | ||
| Chromium | ||
| Copper | ||
| Mercury | ||
| Lead | ||
| Zinc | ||
| EOX: extractable halogens | ||
Table 4: British BioGen/UK Code of Good Practice pellet standards
France
The French-based International Association for Bioenergy Professionals, ITEBE, created a Pellet Club. Its aim is to promote the quality of fuels and it has established a quality label. The ITEBE quality charter for pellet manufacturers (BIG, French Pellet Club, Charte Qualité) does more than simply outline the various wood pellet standards that exist in Europe; it offers specific advice on determining a quality pellet for various uses.
Denmark
In Denmark the general environment labels, such as Svanenmärket (the Scandinavian Blue Angel) or Die Blumme, are used for pellets.
Germany
| Specification | Germany DIN 51731 / DIN plus | |
| 5 Längenklassen sonst gleich [cm] | ||
| Size | HP1 | Length Dia. |
| >30 >10 | ||
| HP2 | 15–30 6–10 | |
| HP3 | 10–15 3–7 | |
| HP4 | <10 1–4 | |
| HP5 | <5 0.4–1 | |
| Bulk density | ||
| Fines %<3 mm | ||
| Unit density | 1–1.4 g/cm³ | |
| Moisture content | <12% | |
| Ash content | >1.5% | |
| Caloric value | 17.5–19.5 MJ/kg | |
| Sulfur | <0.08 | |
| Nitrogen | <0.3 | |
| Chlorine | <0.03 | |
| Arsenic | <0.8 mg/kg | |
| Cadmium | <0.5 mg/kg | |
| Chromium | <8 mg/kg | |
| Copper | <5 mg/kg | |
| Mercury | <0.05 mg/kg | |
| Lead | <10 mg/kg | |
| Zinc | <100 mg/kg | |
| EOX: extractable halogens |
| <3 mg/kg |
Table 5: Germany DIN 51731 / DIN plus pellet standards
Italy
| Specification | Italy CTI – R 04/5 | |||
| 4 categories according origin and with or without pressing aids A, no additives A, with additives B and C | ||||
| Size | 6 mm, 8 mm | 6 mm, 8 mm | 6 mm, 8 mm | 10–25 mm |
| Bulk density | 620–720kg/m³ | 620–720kg/m³ | 620–720kg/m³ | ≥550 kg/m³ |
| Fines %<3 mm | ||||
| Unit density | ||||
| Moisture content | ≤10% | ≤10% | ≤10% | ≤15% |
| Ash content | ≤0.7% | ≤0.7% | ≤1.5% | to be stated |
| Caloric value | ≥16.9 MJ/kg | ≥16.9 MJ/kg | ≥16.2 MJ/kg | to be stated |
| Sulfur | ≤0.05% | ≤0.05% | ≤0.05% | to be stated |
| Nitrogen | ≤0.3% | ≤0.3% | ≤0.3% | to be stated |
| Chlorine | ≤0.3% | ≤0.3% | to be stated | |
| Arsenic | ||||
| Cadmium | ||||
| Chromium | ||||
| Copper | ||||
| Mercury | ||||
| Lead | ||||
| Zinc | ||||
| EOX: extractable halogens | ≤1.0% | ≤1.0% | ≤1.0% | to be stated |
Table 6: Italy CTI – R 04/5 pellet standards
