Forest residue is a valuable energy resource. If stored and handled properly it can be processed into a quality biofuel. As increasing pressure is being placed on replacing fossil fuels with carbon neutral alternatives, the value of residues is set to increase. Forest residue recovery for biofuel is becoming cost effective.
Forest residues are produced during harvesting operations. Decisions made at the harvest planning stage can affect the quality and quantity of residue. This can maximise possible returns to the forest owner from a product which is otherwise a costly waste. See Problems with Residues in Benefits of Removing Residues article.
Efficient recovery of high quality in-forest residues depends on good communication between biofuel contractors, harvesting operators and harvest planners.
There are several factors critical to producing a biofuel which include: good access to residue for on-highway truck and trailer units; high volumes of residue collected in one place; and dry and clean residue.
To improve the viability of using forest residues as a biofuel, various issues need to be addressed at harvest planning stages. Harvesting operations can affect forest residues in a variety of areas:
Planning is required for on-highway configured trucks and/or low-loaders to access residue piles. This access must be maintained for periods of up to 6 to 12 months following completion of harvesting operations.
Back to top...
Planning is required for either in-forest storage or residue removal to an alternative site. In-forest storage on dry, open ground can result in reduced moisture content, minimal dry matter losses and reduced cost of delivered energy.
Landing residues are the most cost effective residue for producing biofuels as they are already at roadside. Hauler apparatus tend to produce more residues and often have slash disposal issues which are mitigated by removal.
Residues from a ground-based harvesting operation can be collected from the cutover by forwarders or bundlers. This will only be viable if the demand for biofuel increases, with an accompanying increase in value.
Collection of residues from steep hauler country is not currently viable or practical.
Back to top...
The volume and size distribution of residue is influenced by the type of log making being used: motor manual, computer optimised, or mechanised.
Computer optimised log making tends to produce more residues in longer sections than motor manual operations. Mechanised operations tend to produce more residue in more pieces than motor manual operations.
Segregation of different residue types (pulp or chip logs, stem sections, slovens and large branch pieces) is important and can enable separate processing of residue types into higher value products such as pulp chip.
Back to top...
The nature of the crop can also have a marked influence on the volume of residues. Open grown crops with significant stem malformation will produce relatively high volumes of residue. A high quality crop, with well formed stems and limited branching will produce low volumes of residue.
Back to top...