Emerging biomass conversion technologies, such as small scale mobile biochar or pyrolysis/torrefaction machines, aim to use forest residues left after extracting merchantable timber from timber harvest or fuel reduction thinning operations. The residues generated from these operations typically produce low quality feedstock which may not be suitable for new biomass conversion technologies. In an effort to increase feedstock quality, our study separated sub-merchantable trees and tops from piled limbs during the timber harvest. A portion of the separated material was further processed to remove limbs to create five material types: processed and unprocessed, conifer and hardwood stem wood, and slash (stems, limbs and chunks). These materials were comminuted with a disc-chipper or a grinder. The quality of the feedstock produced was characterized by moisture content, particle-size distribution, bulk density, and ash content. Moisture content of sample collected ranged from 19 to 29%. The mean geometric lengths for unprocessed hardwood, unprocessed conifer, processed hardwood, processed conifer, and slash were 20.60, 18.27, 18.16, 17.41, and 47.47 mm, respectively. The bulk density of the five material types ranged from 137.20 – 322 kg/m3. The least amount of ash were observed in processed conifer samples (0.27%) and greatest in ground slash (1.5%). The results showed that a high quality feedstock can be produced by separating stem wood from other residues during a harvest.
AUTHOR Waste to Wisdom
Waste to Wisdom is funded by a grant from the U.S. Department of Energy under the Biomass Research and Development Initiative program, Award Number DE-EE0006297, and is led by Humboldt State University with support from 15 regional partners.