The commercial use of low-value forest-origin biomass has long been considered for its potential to offset the cost of reducing wildfire hazard. The production of biochar simultaneously consumes low-value forest biomass and produces stable charcoal that, when applied to dryland agricultural soils, can increase water holding capacity and crop yield. In this way the production of forest-origin biochar has the potential to promote forest restoration, foster forest-related employment, increase agricultural competitiveness, and sequester carbon. Biochar offers the greatest opportunity where dryland food crops, limited water availability, existing energy transmission infrastructure, and high-fire hazard forests share the same landscape. In this paper we describe a landscape-level study based on this scenario to optimize wildfire hazard reduction treatments, biochar facility locations, and agroeconomic outcomes to evaluate the potential benefits needed to carry the costs of biochar production.

The industrial production of long-lived charcoal products (commonly referred to as biochar) from otherwise shorter-lived logging resides (commonly referred to a slash) has been proposed as a means to increasing terrestrial carbon storage thus mitigating global warming caused by anthropogenic greenhouse gas emissions. We present a generalized model that describes the temporal dynamics of biochar carbon stocks, relative to carbon of unmodified logging residue, and evaluate the sensitivity of carbon storage to various biophysical and production parameters. Using this model, we then attribute net carbon storage to several potential biochar production scenarios, specifically engineered to use wood recovered from harvests prescribed to reduce fire hazard in mixed-conifer forests of South-central Oregon. Relative to a baseline scenario where logging residue is left to decay on site, the net carbon storage attributed to 20 years of biochar production is generally negative for the first several decades, then remains positive for several centuries at levels approximately one-fourth the total feedstock carbon processed. Positive net carbon storage and the time required for it to manifest is notably sensitive to biochar conversion efficiencies, logging residue decay rates, and alternate baseline fates of logging residue. The magnitude of net carbon storage, and the time required for it to become positive, is largely similar across range of production facility types. Moreover, the time required for net carbon storage to become positive, and its magnitude over the first 100 years is notably insensitive to biochar decomposition rates provided biochar decays at least ten-times slower than the logging residue it is made from.

The development of a market for currently non-merchantable forest material, such as harvest residues or small diameter trees, has been suggested as a possible win-win solution that could: (i) provide a material that can be processed in rural communities reeling from changes in the forest products industry and policy environment; (ii) capture more value from timber management activities; and (iii) provide a financial incentive for treatments to reduce wildfire risk or restore forest stands. Modeling the supply of this material with spatially-explicit potential demand locations allows for a realistic analysis of the feasibility of such a market to stimulate rural development. We model multiple scenarios for the utilization of harvest residues within the current forest products market in western Oregon. Sensitivity analysis explored the effects of cost of the depots on feasibility, including policy designed to support depot establishment through subsidies. Scenarios were also used to assess the effects of increases in federal harvest activities. Results suggest that with relatively high biomass prices, there is some potential for investment in depots to aid rural communities in western Oregon, but there is little change in either the overall feasibility or the location of depot establishment under scenarios of increased federal harvest.

The effect of the grinder configuration, bit type and screen size, on bulk density and fuel consumption when processing forest harvest residues for energy purposes is analyzed. Residues were divided in three size classes based on the piece diameter and length and were processed in a six treatment structured randomized test using a horizontal grinder. For each treatment the basic density, moisture content, bulk density, particle size distribution, fuel consumption and bark and other non-wood substances content was estimated. No effect of bit type or screen size on bulk density was found when processing branches-and-tops size class residue. For the pulpwood and butt-log-chunks size classes, the knife-edge bits tend to produce a denser material explained in part by their cutting capabilities across the grain compared to the normal hammering process using carbide hammer bits. Fuel consumption was only affected by screen size when processing the branches-and-tops size class. For pulpwood and butt-log-chunks size classes, the use of carbide hammer bits for processing increased fuel consumption between 42 and 48% compared to knife-edge bits. Bark and other non-wood substances content accounted for 11% of the total grinding mixture in the branches-and-tops size class compared to 2.5% in grindings from pulpwood and butt-log-chunks size classes. The branches-and-tops size class residue produced denser bulk material compared to the other classes and consumed less fuel due in part to the higher basic density and increasing amount of fine particles compared to the other analyzed size classes.

ABSTRACT We present a summary of the characteristics of 55 samples of processed forest biomass residues randomly collected from 34 sites in Oregon. Our purpose is to illustrate the wide diversity of field-processed grindings and chips that are currently being produced to inform managers of the potential variability in existing biomass sources. The samples vary widely with respect to moisture content, particle size distribution, species mix, and ash content. We discuss the value of residue classification for downstream processing. The primary use of forest residues is currently for combustion, but stratification of forest residues provides opportunities to create value-added products, provide rural employment, and increase transportation efficiency.