The precise size of wood chips varies, depending on the type of wood and the chipper used to create them. As a general rule, they are created as a byproduct of timber processing, with small branches, off-cuts, and other debris being run through a wood chipper as a way of compacting tree waste. Chips can also be made from larger pieces of wood, assuming that those pieces have no other uses.
Suitability for heat/power generation
Virgin wood is suitable for a range of energy applications. It can be burned for heat and/or power at a range of scales. New 'second generation' technologies are being developed which are capable of producing a range of liquid or gaseous transport biofuels from woody material.
Wood from forestry
The primary source for timber. This includes wood from private and state owned woodland and plantations. As harvested, wood will be at a range of moisture content, and of a variety of physical shapes and sizes.
Wood from arboricultural arisings
This includes residues from:
- Managing municipal and private parks and gardens
- Tree surgery and pruning
- Maintaining railway and road verges.
In many ways very similar to forestry residues, though possibly including a larger proportion of brash material and less round wood, leading to a higher percentage of bark and leaves.