Summary

Forest biomass is defined as any plant or tree material produced by forest growth. Much of the forest biomass is currently used as a raw material in the manufacturing and refining of traditional types of wood products, such as lumber, plywood, paper, chemicals, and many other items. These types of items are typically produced from trees that are over 12 cm in diameter at breast height (dbh), reasonably straight, and otherwise sound. Biomass of these trees is considered merchantable.

Forest biomass energy systems are capable of using otherwise wasted or “unmerchantable” biomass. Specific types of biomass targeted for use in energy systems include: tops and branches of trees left after timber harvests, poor quality trees in managed forests, trees removed during land clearing operations, wood waste from urban areas, and wood residues produced by sawmills. As demand for these types of forest biomass increases, their value will increase, and they will become merchantable.

Chipping is a way of processing woody material into an acceptable fuel, and simultaneously improving bulk volume, homogeneity and handling characteristics of fuel raw materials from the forest. Chipping is performed in the forest, at the landing (most common), or close to the landing. Logging residues are only rarely transported on road. But chipping has some disadvantages as well. Storability is negatively affected, i.e. once the material is chipped, it is important to use the fuel as soon as possible to prevent excessive microbial activity causing health hazards through spore emission, energy losses and even self ignition of the chipped material.

A possible alternative to improve forest fuel-logistics is to make bundles. Bundles may form a relatively uniform handling unit, allowing full load capacity if compression is enough. Other possible advantages are efficient handling in loading, processing, etc. if the size of the bundles is optimal. Bundles can be assumed to offer good storing characteristics. At the same time the use of conventional timber trucks offer good possibilities for “return loads” and long-term planning.

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