Sunday, May 3, 2009
8-11
The variability of biofuel feedstock availability and delivered price using GIS and the IBSAL dynamic model
James D. Stephen1, Shahab Sokhansanj2, and Xiatao Bi2. (1) Department of Wood Science, University of British Columbia, 2424 Main Mall, Vancouver, BC V6K 1Z4, Canada, (2) Department of Chemical and Biological Engineering, University of British Columbia, 2360 East Mall, Vancouver, BC V6K 1Z3, Canada
The purpose of this research was to quantify feedstock supply risk over the lifetime of an agricultural residue-based (straw and chaff) biorefinery and to determine the range of delivered prices. The Peace River region of Alberta was used as a case study location, with a geographic information system utilized for data analysis. Inter-year availability of crop residues was highly variable over the 20 year period under study, with the range from 200% of the average availability for the maximum scenario to zero biomass available for the minimum scenario. Biomass availability is a function of grain yield, the biomass to grain ratio, the cropping frequency, and residue retention rate used to ensure future crop productivity. Using minimum, average, and maximum supply scenarios, delivered price was determined using the dynamic (time-dependent) Integrated Biomass Supply Analysis and Logistics (IBSAL) simulation model. Five biorefinery capacities, ranging from 50,000 to 500,000 tonnes of feedstock per year, were analyzed. Since no biomass was available to model in true minimum years, a simulated minimum of half the average availability was used. Delivered cost, including harvest and transportation, for the 50,000 t plant ranged from $24.01 t-1 for the maximum availability scenario at the Sexsmith site to $42.63 t-1 for the simulated minimum scenario at the Fahler site. Since feedstock cost is a large component of total operating cost of a biorefinery, feedstock supply variability and delivered cost inconsistency should be primary decision criteria for any future biorefinery projects.