Tools and Resources
There is a wide range of biomass potentially suitable for energy use, however most types of conversion equipment works effectively with a very few types and forms of biomass fuel.
Even with a specific form of fuel, such as wood chips, there can be major differences in characteristics and properties between different batches chipped using different chippers, from different material, with different moisture content.
This means that while it is all eminently usable, one batch will allow a particular piece of equipment to operate according to specification, but another may cause blockages in the fuel feed line, inefficient operation, emissions, condensation in the flue, or automatic shut down of the equipment as it moves outside its design operating regime. In different equipment, however, the second batch of fuel may be perfectly acceptable.
Sustainability standards too are required, and gradually being developed to ensure that biomass is only derived from sustainable, legal sources. CPET, the Central Point of Expertise on Timber Procurement, provides detailed information and advice on how public sector buyers and their suppliers can meet the UK Government’s timber procurement policy requirements in practice, and demonstrate that timber supplied is legal and sustainable.
CEN/TC335 was the technical committee responsible for developing the European Norms (EN) to describe all forms of solid biofuels within Europe, including wood chips, wood pellets and briquettes, logs, sawdust and straw bales. These have been adopted by the British Standards Institution (BSI) to form BS EN.
The ISO extends these standards beyond Europe, and now many of the BS EN standards have been superseded by BS EN ISO standards.
These standards allow all relevant properties of the fuel to be described, and also the internationally accepted test procedures to measure the various properties. As well as the physical and chemical characteristics of the fuel as it is, they also provide information on the source of the material.
Woodsure is an accreditation scheme for assuring the quality and suitability of wood chip, pellets, briquettes, logs and hog fuel (shred).
Woodsure Accreditation of a woodfuel supplier means that these products have been tested to ensure they meet the BS EN or Önorm woodfuel standards that have become the established measure in the European biomass industry.
Woodsure accredited woodfuel assures customers that the fuel they are purchasing fulfils the appropriate specification for their equipment. It helps to guarantee a high standard and reliability in the supply chain.
While the CEN/TC 335 standards are intended to be the universal standards for solid biofuels across Europe, prior to these many countries developed their own standards. The Austrian Standards Institute is ÖNORM. While ÖNORM is now adopting its own implementations of the CEN/TC 335 standards, many Austrian boilers have been installed in the UK and specify fuel according to ÖNORM M7 133 for wood chips (Woodchips for energy generation: quality and testing requirements) and ÖNORM M7 135 for pellets. Sizes such as G30 are ÖNORM sizes and still regularly encountered.
The German Standards Institute (Deutsches Institut fur Normung) also developed its own biomass fuel standards DIN 66 165, and these too are sometimes encountered.
In addition to specifications for biomass fuels, there are also specifications for biomass combustion equipment. BS EN 303-5:2012 applies to heating boilers for solid fuels, hand and automatically fired, nominal heat output of up to 300kW. It is the local UK implementation by the BSI of EN 303-5.
BS EN 303-5:2012 covers properties such as performance, efficiency, emissions, thermal output, pressure testing, safety measures and testing.
In order to demonstrate compliance with any system of standards, it is necessary to have independent testing.
The general fuel specifications and classes for all solid biofuels are set out in BS EN ISO17225-1:2014, which defines certain parameters and property classes. On top of this are BS EN ISO17225 parts 2 to 5 which cover the fuel specifications and classes for specific types of solid biofuels for non-industrial usage, such as wood pellets, chips, firewood, etc.
Some of the key standards that apply to solid biofuels are listed below.
The old BS EN standards have in many cases now been superceded by the ISO equivalent. In these cases the old BS EN standards are in brackets.
| Standard Reference | Title |
| BS EN ISO 16559:2014 (BS EN 14588:2010) | Solid biofuels – Terminology, definitions and descriptions |
| BS EN ISO 18134-1:2015 (BS EN 14774-1:2009) | Solid biofuels – Determination of moisture content – Oven dry method – Part 1: Total moisture – Reference method |
| BS EN ISO 18134-2:2015 (BS EN 14774-2:2009) | Solid biofuels – Determination of moisture content – Oven dry method – Part 2: Total moisture – Simplified method |
| BS EN ISO 18134-3:2015 (BS EN 14774-3:2009) | Solid biofuels – Determination of moisture content – Oven dry method – Part 3: Moisture in general analysis sample |
| BS EN ISO 18122:2015 (BS EN 14775:2009) | Solid biofuels – Determination of ash content |
| BS EN ISO 18135:2017 (BS EN 14778:2011) | Solid biofuels – Sampling |
| BS EN ISO 14780:2017 (BS EN 14780:2011) | Solid biofuels – Sample preparation |
| BS EN ISO 18125:2017 (BS EN 14918:2009) | Solid biofuels – Determination of calorific value |
| BS EN ISO 17225-1:2014 (BS EN 14961-1:2010) | Solid biofuels – Fuel specifications and classes – Part 1: General requirements |
| BS EN ISO 17225-2:2014 (BS EN 14961-2:2011) | Solid biofuels – Fuel specifications and classes – Part 2: Wood pellets for non-industrial use |
| BS EN ISO 17225-3:2014 (BS EN 14961-3:2011) | Solid biofuels – Fuel specifications and classes – Part 3: Wood briquettes for non-industrial use |
| BS EN ISO 17225-4:2014 (BS EN 14961-4:2011) | Solid biofuels – Fuel specifications and classes – Part 4: Wood chips for non-industrial use |
| BS EN ISO 17225-5:2014 (BS EN 14961-5:2011) | Solid biofuels – Fuel specifications and classes – Part 5: Firewood for non-industrial use |
| BS EN ISO 17828:2015 (BS EN 15103:2009) | Solid biofuels – Determination of bulk density |
| BS EN ISO 18123:2015 (BS EN 15148:2009) | Solid biofuels – Determination of volatile matter |
| BS EN ISO 17827-1:2016 (BS EN 15149-1:2010) | Solid biofuels -Determination of particle size distribution. Oscillating screen method using sieve apertures of 1 mm and above |
| BS EN ISO 17827-2:2016 (BS EN 15149-2:2010) | Solid biofuels -Determination of particle size distribution. Vibrating screen method using sieve apertures of3.15 mm and below |
| BS EN ISO 17831-1:2016 (BS EN 15210-1:2009) | Solid biofuels – Determination of mechanical durability of pellets and briquettes. Pellets |
| BS EN ISO 17831-2:2016 (BS EN 15210-2:2010) | Solid biofuels – Determination of mechanical durability of pellets and briquettes. Briquettes |
| BS EN 15234-1:2011 | Solid biofuels – Fuel quality assurance – Part 1: General requirements |
| BS EN 15234-2:2012 | Solid biofuels – Fuel quality assurance – Part 2: Wood pellets for non-industrial use |
| BS EN 15234-3:2012 | Solid biofuels – Fuel quality assurance – Part 3: Wood briquettes for non-industrial use |
| BS EN 15234-4:2012 | Solid biofuels – Fuel quality assurance – Part 4: Wood chips for non-industrial use |
| BS EN 15234-5:2012 | Solid biofuels – Fuel quality assurance – Part 5: Firewood for non-industrial use |
| BS EN 15234-6:2012 | Solid biofuels – Fuel quality assurance – Part 6: Non-woody pellets for non-industrial use |
Woodsure Accreditation means that these products have been tested to ensure they meet the EN and Önorm standards for woodfuel quality that have become the established measure in the European biomass industry.
Woodsure accredited woodfuel assures customers that the fuel they are purchasing fulfils the appropriate specification for their equipment. It helps to guarantee a high standard and reliability in the supply chain.
Woodsure uses an ongoing assessment regime, ensuring that each accredited supplier is regularly visited and evaluated, thus maintaining a consistently high standard of fuel.
Whilst maintaining rigorous standards, the testing and evaluation procedure is straightforward – testing the product at the point of production and supply – and achieved with minimal operational impact or expense for producers and suppliers.
Woodsure provides legitimacy for woodfuel providers and confidence for their customers.
Woodsure also seeks to support woodfuel production businesses, enabling them to develop and improve, and in doing so create a strong, reliable supply chain.
There are now a number of independent test labs accredited by the UK Accreditation Service for the testing of biomass fuels. To find an up-to-date listing visit the UKAS website and search for biomass fuel testing.