Abstract:

With an increasing societal desire to move towards renewable energy sources, interest in utilizing forest logging residues, logging slash, as a feedstock for new energy products is expanding. The Northwest Advances Renewables Alliance (NARA) is working to develop processes for transforming logging residues or slash into aviation fuel, Jet-A. As part of NARA, this study evaluated the availability, utilization, and the material that would remain on sites following clear-fell logging in the Pacific Northwest (USA). Little work has been performed to quantify the volume of harvest residues that are available for biomass material or to determine the volume remaining on site after harvesting with current utilization practices for private forest lands in the Pacific Northwest (PNW). To quantify these two amounts, the volume from logging residue from six sample harvesting units was measured to determine the available biomass and the quantity that remains on site. First, all of forest harvest residues piles were measured; these are considered the available biomass sources. Second, transects with a minimum total length of one-thousand-foot line-intersect sampling was performed to estimate the volume of residual material, not placed into piles, that will remain on site. The results will show both what is available for collection and the minimum amount of slash that will remain in the unit. The results from this study’s measurement showed that the previous estimates of available residues in piles, may overestimate available residues by at least 20%. The volume of residues left in piles was dependent on logging system. Cable yarding left nearly 60% of total logging residue that remained on site. The average pile ranged between 62 m3/ha and 79 m3/ha remaining on site. Ground-based operations using shovels may leave as little as 39 % on site with a range between 79 m3/ha and 40 m3/ha) remaining on sites with 110 m3/ha in piles.

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