Integrating biomass recovery operations into commercial timber harvesting: the New Zealand situation
In most countries biomass recovery from existing timber harvesting operations is recognised as an important component of any bio-energy program. At present, there are very few biomass recovery operations in New Zealand, despite the very large amount of residue generated by large-scale harvesting operations in plantation forests. Much of this residue is readily available post-harvest at landings, with a major concern being the contamination. Currently, residue constitutes a problem for both processing as well as the subsequent planting. A research project has commenced to help assess what an optimal residue recovery system may be. The paper considers what strategy could be employed to successfully integrate biomass recovery into NZ logging operations, with the integration of biomass recovery into the harvesting operation being key. Based on both international literature as well as extensive field visits three favourable options are established. Productivity and cost estimates are provided: with both the post-harvest residue recovery from the landing using a tub grinder, as well as using off-road trucks to transport the residues to a secondary landing for comminution estimated at 34 NZ$/ton. Whereas the post-harvest option provides for easier logistics, the concurrent recovery option will yield both greater quantity as well as quality biomass. Using a bundler to accumulate slash, and then comminute at the power plant is expected to increase the cost to 44 NZ$/ton. Finally, limitation and future research considerations are also discussed.