Virgin Wood
Virgin Wood
Virgin wood consists of wood and other products such as bark and sawdust which have had no chemical treatments or finishes applied. Wood may be obtained from a number of sources which may influence it's physical and chemical characteristics.
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.
Physical Characteristics
Virgin wood is untreated and clean. It may range in moisture content from oven dry to 60% or higher as freshly harvested, green wood. As received there may be physical inclusions from the growing or harvesting processes, such as mud, stones, ice or nails, which may need removing before further processing or combustion. There may also be chemical contaminants from the soil, water or air, or any pesticides or other sprays used, such as heavy metals, halogens or other trace materials. In general levels of these will be very low.
It may be in a range of physical forms:
- Bark
- Brash and arboricultural arisings
- Logs
- Sawdust
- Wood chips
- Wood pellets and briquettes
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. In addition to harvesting, some level of pre-processing is likely to be required. Transport and storage will also be necessary.
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. Material may be chipped on site to reduce volume for removal in general purpose chippers that do not produce chips of sufficient quality for many combustion systems. As for wood from forestry above, pre-processing, transport and storage may need to be considered.
Wood Processing Industry Co-products
The wood processing industries, such as sawmills and timber merchants, are also a source of virgin wood in the form of offcuts, bark and sawdust. Many transport, pre-processing and storage issues may be similar to those for forestry products, however the material obtained is likely to be in different forms from forest or arboricultural products.
There are likely to be a number of different output streams with different characteristics:- Sawmill offcuts may include a high proportion of bark
- Some material may have been kiln dried to extremely low moisture content making it potentially very suitable for wood pellet manufacturing or blending with material at higher moisture content
- There may be sawdust at a range of moisture content from different stages of processing, and again very dry sawdust from kiln dried timber may be very suitable for wood pellet manufacture
Since October 2007, the Environment Agency in England has declared that such virgin wood residues are no longer classified as waste.
Importing Wood
Plant health controls apply to a wide range of imported wood products. This includes material imported for use as woodfuel. |
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