Wood fuel supply chains


Energywood Chip Supply Chain from Integrated Harvesting

Integrated harvesting is similar to the standard roundwood harvesting method. The same machines types are used in both supply chains. One of the key differences in integrated harvesting is that at the planning stage it is known that woodfuel will be produced from some, or all of the wood recovered from the thinning. Because of this, it is not necessary to cut all the log lengths to standard sizes that are required by the sawmills / pulp mills. It is also not necessary to completely remove all the branches from the stem, only green foliage is removed as much as possible, the rest can be used as wood fuel. This method should recover significantly more biomass than the roundwood chip supply chain.

In this supply chain, the sawlog and/or stakewood is produced as normal for sale to the sawmills. The pulpwood part of the stem is crudely delimbed into variable lengths of around 4.3 m without a specified top diameter. This is the energy assortment for chipping.


Harvesting

Like the roundwood chip supply chain, forest harvesters are used to perform a combined line and selection thinning. Typically between 30\% - 40\% of the crop is removed, depending on the silvicultural prescription of the thinning. The harvester cuts, fells, delimbs, and crosscuts the trees into specified lengths depending on the size of the trees. Small sawlog is usually prioritized, which has a 2.5 m length, and a minimum small end diameter of 14 cm. Small sawlog can be cut from the lower sections of the larger trees in the forest. The remaining portions of the stems are crudely delimbed into variable lengths of about 4.3 m in length with no restrictions on small end diameter. The crude delimbing retains some of the branches, it is only desirable for green foliage to be removes. This is accomplished by setting loose the delimbing knives on the harvester head. The pressure of the rollers on the harvesting head can also be increased to break the bark along the stem, which can facilitate drying during storage. These products (or assortments) are stacked separately at right angles to the extraction rack. The tree top and branches are used as a brash mat underneath the machines, and are not recovered from the site.

Energywood Chip

Forwarding

The forwarding occurs the same as the roundwood chip supply chain, where:
Shortly after harvesting, a forwarder machine travels into the forest and picks up the small stacks of assortments with a crane. The assortments are loaded onto a bunk on the back of the forwarder. Once the bunk is full, the forwarder travels to a stacking area beside the forest road. The assortments are piled separately into large stacks.

Storage and Transport

The small sawlog assortments are transported to the mill by timber truck. The energywood, which is to be chipped into a fuel, either:

  • i) Remains in the stacks at the forest for sufficient time for seasoning to occur (at least one summer).
  • ii) Transported to a terminal for storage for sufficient time for seasoning to occur (at least one summer).

For some benefits on using a terminal for storage, see the round wood chip supply chain.


Video of supply chain operations