How is harvesting & mill waste re-used?

When forest trees are harvested and the logs (bolewood) removed for further processing, significant quantities of woody material from the heads and branches of the harvested trees is left scattered about the forest. In addition, in the milling process of converting round logs into sawn rectangular boards or beams, there is considerable waste generated in off-cuts (woody biomass) and sawdust. Not so long ago, it was mostly just burnt, but now it is more often made available for other uses.

The most common uses for woody biomass generated from sawmill waste have been as woodchips or firewood, while sawdust has often been used as garden mulch. Increasingly now around the world, woody biomass is being harnessed in managed processes either from the forest or at processing centres (especially sawmills) to produce energy through controlled burning (furnaces) to produce steam, or through gasification (the slow heating of wood pellets or chips in the absence of oxygen and under high pressure). Woody biomass is available in vast quantities as a by-product of forestry and timber processing. In Europe and North America, it is becoming a preferred fuel source for heat and power plants, including gasification plants.

With the new emphasis on renewable energy, and the introduction of new materials and technologies, wood is coming to the forefront as an important energy source. Countries like Sweden, Finland and Austria are showing how major parts of their national energy requirements can come from residues and wastes from sustainably managed forest and timber industries.

Within Australia’s forestry industry, processing facilities are converting residue into heat energy, and a number of projects are underway to develop and expand larger scale production of electricity from biomass linked to forestry and timber processing facilities.