|Abstract or Summary
- This dissertation presents an analysis of transportable biomass conversion facility design to evaluate the conceptual and economic viability of a mobile and modular biomass conversion supply chain in the Pacific Northwest, USA. The main goal of this work is to develop a decision support system to more effectively and sustainably use residual biomass from commercial harvesting operations that are currently piled and burned as part of site preparation. To complete this research a comprehensive biomass supply chain landscape characterization, modeling and optimization study was completed to provide an analysis of transportable biomass conversion facility design and evaluate its potential economic viability from strategic, tactical and regional perspectives. The long-term goal of this research is to help enable a sustainable marketplace for forest harvest residuals to effectively utilize this waste material and support regional economies.To complete this research the following components were developed: a comprehensive supply chain characterization, a conversion technology and machine rate model, a plant facility costing model, regional spatial and biomass availability data and two economic optimization models. My specific contribution was to examine a spectrum of economic tradeoffs and supply chain considerations including move frequency, logistics, energy costs, moisture content, product viability considerations and regional context related to the implementation of transportable biomass conversion facilities that had previously not been evaluated. Transportable facilities ranging from 15,000-50,000 BDT year scale for three products (biochar, briquettes, torrefied wood) within Oregon, California and Washington are reviewed. The work considers various supply chain pathways including supply options at landings (burn, grind, chip, bale), centralized landings (grind chip), biomass conversion facilities (biochar, briquettes, torrefied wood) and delivery to final market. Within the body of this work, I present three papers where I systematically evaluate the implications of transportable facility design (scale, movement, biomass availability), the economic impacts on the supply chain (logistics, moisture content, product pricing, product production), and the intra-regional variations associated with the system under unique market, product, transportation and energy environments. This analysis was done in an effort to better understand the impacts of transportable conversion facilities and their potential economic viability.A mixed integer linear programming model was developed to characterize, evaluate and optimize biomass collection, extraction, logistics and facility placement over a landscape from a strategic level to evaluate the mobility concept over a five year time horizon. This model was then used to evaluate facility economics of scale, optimal movement frequency, and sensitivity to biomass availability within a Lakeview, Oregon case study facility producing biochar. Results indicated significant advantages with larger scale operations with grid-connected power and limited mobility being preferable to a more mobile facility. Results depend greatly on the landscape, assumed harvest schedule, biomass composition and governing biomass plant assumptions. A tactical-level biomass supply chain model is also developed to evaluate and characterize the temporal, logistics and multi-product aspects of the proposed transportable facility design. The model solves a multi-period, multi-commodity, multi-echelon combinatorial problem to maximize net present value using a genetic algorithm. This model was used to evaluate competing biomass logistical systems, the impacts of moisture content on costs (transportation and drying) for a single facility as well as to evaluate the impacts of product conversion efficiencies, product pricing and co-product production economics for six plant configurations within the Lakeview, Oregon case study. Results generally indicated that system viability is largely dependent on market pricing, plant assumptions and conversion estimates while processing and transportation logistics are smaller, but important contributors for small scale biomass conversion faculty design configurations. Moisture content management was found to be an important factor contributing to conversion drying cost with co-generation of products benefiting from production and thermal efficiencies. It was also found that, given the revenue estimates, biochar was the most probable candidate for commercial success pending on market conditions.Finally, a regional study was completed to extend the transportable facility economic analysis to five sites (Lakeview, Oakridge, Warm Springs, Quincy, Port Angeles) encompassing three states over a five year time horizon with three product configurations and an assumed 50,000 BDT Year feedstock capacity. This research analyzes the effects of regional differences (logistics, biomass quality and quantity, energy rates, log markets) within the transportable system design to gauge potential economic viability and its sensitivities to fuel, energy and transportation distances. Overall, results indicate that there is a fairly small inter-regional product costing variation (<10%) with regions having close proximity to high quality feedstocks yielding the most cost effective products (Quincy, California and Oakridge, Oregon). Additionally it was found that a rise in diesel price, while incentivizing transportable conversion facilities due to more cost effective transportation, would be more than be offset by the higher cost energy consumption during the conversion process when compared with grid-power with the potential exception of biochar. For the products evaluated, biochar seems to be the most logical as it is less dependent on potentially expensive electrical energy, is the most cost effective to transporting converted material long distances and may support a higher market price. Overall, a transportable operation with grid-power could be the difference between a economically viable supply chain operation and one that is not.