Potential ethanol biorefinery sites based on agricultural residues in Alberta, Canada: A GIS approach with feedstock variability

Though numerous studies have investigated optimal locations for biorefineries given the availability of feedstock supplies, few have considered that these supplies could vary over time, thereby potentially failing to meet feedstock requirements. In this paper, we develop a process for identifying a shortlist of five potentially viable biorefinery sites in Alberta, and then consider the stochastic nature of these supplies, and what that variation could mean for supplying a biorefinery. A shortlist of sites was selected based on agricultural residues within a distance of 80 km of the site. Across all sites, a total amount of 16.7 million t [oven dried] y⁻¹ is found to be economically accessible in the province. However, this shortlist is based only on a summation of one-year crop yields surrounding the sites. When crop yield variability (estimated from data over 40 years between 1978 and 2017) is also considered, substantially different results were found. For example, if supply was required to exceed 1.59 million t [oven dried] y⁻¹, 95% of the time, then two selected sites, which were chosen based on one-year crop yields, must be excluded. Under these circumstances the total amount available across sites falls to 12.4 million t [oven dried] y⁻¹. Overall, when variability in supply is included as a criterion, site selection and rankings change, suggesting that site selection using only an average or point estimate is not sufficient. Instead, more sophisticated techniques to investigate feedstock supply variability would be useful.