We analyzed the economics of mobile chipping and transport of biomass from forest residues for energy purposes under uncertainty. A discrete-event simulation model was developed and utilized to quantify the impacts of controllable and environmental variables on productivity in order to determine the most cost effective transportation options under steep terrain conditions. Truck-chipper interactions were analyzed to show their effect on truck and chipper standing time. A costing model was developed to account for operating and standing time cost (for the chipper and trucks). The model used information from time studies of each activity in the productive cycle and spatial-temporal information obtained from geographic information system (GIS) devices, and tracking analysis of machine and truck movements. The model was validated in field operations, and proved to be accurate in providing the expected productivity. A cost distribution was elaborated to support operational decisions of forest managers, landowners and risk-averse contractors. Different scenarios were developed to illustrate the economic effects due to changes in road characteristics such as in-highway transport distance, in-forest internal road distance and pile to trailer chipper traveling distances.

Fuel-reduction treatments on steep slopes across federal forests of the western United States have been limited by the high costs associated with cable logging on steeper slopes combined with poor market prospects for small-diameter material (Bolding 2003, Rummer 2008, Han et al. 2016). The emergence of tethered cut-to-length harvesting systems and small wood markets (e.g., biochar) could decrease costs and increase revenue generated from treatments. Over the course of 3 weeks, we observed both tethered (steeper slopes) and untethered cut-to-length fuel-reduction treatment on the Fremont-Winema National Forest in south-central Oregon and interviewed operators. We used those data to derive and contrast hourly costs and productivity for the harvester and forwarder. This was the first time a tethered harvester and forwarder were used in a fuel-reduction treatment on federal forests in this region. We developed and tested a variety of work time model forms for each machine. The mean utilization rate for the harvester was 64 percent on 17 tethered consolidated corridors but 87 percent on 28 untethered consolidated corridors. Similarly, the forwarder had a mean utilization rate of 76 percent on 30 tethered trips and 89 percent on 114 untethered trips. This reduced utilization rate could be because of the direct effects of tethering, the increased complexities of operations associated with steeper slopes, and the stand characteristics (e.g., lower stand density and tree sweep) associated with steeper slopes. Costs during tethered operations were higher than during nontethered operations, but lower than previous reports using cable logging.

The moisture content in forest harvest residues is a key factor affecting the supply cost for bioenergy production. Fresh harvest residues tend to contain higher amounts of water, thus making transportation inefficient. Additionally, fresh harvest residues contain greater amounts of needles and bark that may reduce the polysaccharide content, thus affecting the production of liquid fuels derived from cellulosic components. In this study, we estimated the downstream economic effect in the supply chain of collecting, grinding, transporting and pretreating fresh versus aged residues. Specifically, we analyzed the effect of feedstock moisture content on grinder fuel consumption, bulk density, bark and needle content, and polysaccharide proportion. Fresh forest harvest residues were 60% moisture content (wet basis) and aged forest residues were 15% moisture content. The bark and needle proportion is 6.1% higher in fresh residue than in aged residue. Polysaccharides were 26% higher in aged residue than in fresh residue. On a dry-tonne basis, the cost of grinding fresh residues was about the same as that of aged residues. However, considering the difference in bulk density on transportation cost and the difference in polysaccharide yield, the value gain for in-field drying ranges from US$29.60 to US$74.90 per ovendry tonne.

This study investigates the environmental burdens of three logistics system scenarios for residue processing and transportation under different road type distri

: Transportable biomass conversion facilities producing biochar, briquettes, and torrefied wood are modeled and optimized for five different sub-regions within the Pacific Northwest. Subregional case studies in Quincy, California; Lakeview, Oregon; Oakridge, Oregon; Port Angeles, Washington; and Warm Springs, Oregon, are evaluated to characterize the potential economic viability of these novel transportable designs. A mixed integer program is used to characterize the supply chain from residue extraction to market optimizing transportation, production, and plant mobility in order to minimize the supply chain costs. Regional variations including log specifications, energy rates, trucking, and logistic capacities are considered within the model and supporting analyses to differentiate regional costs and market viabilities. It was found that the optimal transportable design included facility movement on a 1 to 2.5 year frequency depending on product and region with biochar being the most likely to be economically viable. Regional feedstock composition and availability was the biggest indicator of lower cost production. Supply chain costs varied by 5%-10% depending on product and region being produced. Transportation and mobilization were found to account for 15%-30% of the overall supply chain cost. Quincy, California, and torrefied wood were found to have the lowest of these costs due to low move frequency and high wood availability while Port Angeles, Washington, with briquettes was the highest. With regards to fuel price sensitivity, torrefied wood was the most sensitive as its conversion process was most energy intensive (±12%-13%) and biochar least sensitive (±3-5%).Transportation accounted for 5% to 30% of the fuel price variation due to diesel prices depending on product and region. When including grid-connectivity, cost reductions were approximately 6%-7% for biochar, 27%-29% for briquettes and 33%-38% for torrefied wood. These findings indicate biochar as the most likely candidate for a transportable conversion system given its relatively low power consumption, high allowable moisture content, and low product transportation cost. Quincy, California, was found to be the most desirable sub region with the lowest overall production costs attributed to its high input quality feedstock and relative accessibility; its higher grid-connected power cost also makes transportable options relatively more attractive than other off-grid locations. Port Angeles, WA had the highest production costs and lowest grid-energy costs. Our results indicate that a rise in diesel price, while incentivizing transportable conversion facilities due to more cost effective transportation, would be more than offset by the higher cost energy consumption during the conversion process when compared with grid-power with the potential exception of biochar. Overall, we see a transportable operation with grid-power would likely be the difference between an economically viable supply chain and one that is not. Keywords: Biomass supply, Biomass products, Facility location, Mixed integer programming, Strategic planning, Transportable plants.