Biomass and forestry

Peter Hall from Scion talks about the biomass streams produced by the forestry industry.

Forestry waste is produced at nearly all stages of wood processing. For example, the trunk might break leaving a top that is too thin to be used as a log when a tree is felled, branches must be trimmed off creating smaller unusable wood residue, the bark may be removed during processing at the sawmill or sawdust may be produced when the logs are further processed.

Transcript

Peter Hall

We are looking at a wide range of waste resources. There’s forest harvesting residues, agricultural crop residues such as straw. We’re looking at municipal solid waste, municipal effluence, industrial wastes from diary factories, meat processing, land fill gas, dairy farm waste and wastes from intensive farming of pigs and poultry.

The forestry sector is one of the largest potential resources of biomass, and that is because there’s small portions of residual material created right through the supply chain when you're taking trees to logs and through wood processing. Initially when trees are felled often they hit the ground and they break so there is small sections of the stem at the top of the tree which is smashed off and is not extracted because its too small to make into a log. Then when the rest of the stem is extracted to road side its cut into logs of various grades, and during that process it’s very common for small sections of the stem to be cut off because they have a defect in them, so those get cut off and discarded at roadside. Then further down the chain when the logs arrive at the sawmill the exterior of the log is sawn off, most of that gets chipped but prior to that the bark is peeled off, sawdust is created as the material is cut up, and then once you've got a length of say 4 by 2 which has been sawn out of a log, sometimes that has defects and often those are discarded as well, so right the way through from getting from a tree in the forest to a piece of 4 by 2 that goes into a house there’s pieces of woody residue created all the way through.

Acknowledgements: KQED QUEST, some rights reserved TVNZ TELEVISION ARCHIVE Paul Brooker Ian Wilson