Classification of used wood in European solid biofuel standard: Fuel specification and classes (EN 14961-1)

The work of the BioNormII on Fuel specification and classes (Task IV) has very valuable in upgrading of EN 14961 to European standard. Testing of the draft versions of EN 14961 in companies and collecting feedback from associations has provided useful information from practise in setting threshold values for property tables in Part 1 of EN 14961 and proposal for classification of product standards. The Task IV has also made a comprehensive study of current classification of used wood (waste wood) including implementation of European legislations and standards. The study included also analysis of different used wood sortiments and their composition especially con­ taminants. It is necessary to define the impact of possible contaminants on the energy utilisation of used wood. This is helpful for categorisation, as well as for identification and characterisation of the contaminants. From an environ­ mental point of view, the risks of used wood combustion are air pollution from flue gases or leaching of hazardous substances from ash after disposal. Operation failure, normally appearing as boiler deposit formation or corrosion, is a technical issue that also needs to be considered. Mechanically, problems in fuel conveyors may occur due to glass, fittings, and various fastening systems that are attached to “used wood” products. Another important aspect to be ac­ counted for is issues related to occupational health. All these aspects were surveyed during the study. The project also made a proposal for overall categorisation of chemically treated industrial wood residues and used wood. In this clas­ sification used wood is divided in 4 categories A, B, C and D. Categories A and B are classified under EN 14961-1– Solid biofuel standard and class C under EN 15359–Solid recovered fuel. Fuels falling into category C should be in­ cinerated according Waste Incineration Directive (2000/76/EC). Class D wood is treated by wood preservatives and is hazardous waste.