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Subregional Comparison for Forest- to-Product Biomass Supply Chains on the Pacific West Coast, USA

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Applied Engineering in Agriculture. 34(1): 157-174 . (doi: 10.13031/aea.12526) @2018
Authors:   Michael David Berry, John Sessions, Rene Zamora-Cristales
Keywords:   Biomass supply, Biomass products, Facility location, Mixed integer programming, Strategic planning, Transportable plants.


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.

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