Geospatial identification of optimal straw-to-energy conversion sites in the Pacific Northwest

Previous attempts to develop straw-based bioenergy systems have stumbled at costs of transporting this low-density resource to large-scale, centralized facilities. Success in developing small-scale, distributed technologies (e.g syngas or pyrolysis bio-oil) that reduce these costs will depend on closely matching system requirements to spatial distribution of available straw. We analyzed straw distribution in the Pacific Northwest to identify optimal sites for facilities ranging from a pilot plant currently under development to larger ones of previous studies. Sites for plants with capacities of 1, 10, or 100 million kg straw y(-1) were identified using a 'lowest-hanging-fruit' iterative siting process in which the location of maximum density of straw over an appropriately sized neighborhood was identified, distance from that point necessary to include desired quantity of straw measured, straw assigned to that plant removed from the raster, and the process repeated until all available straw had been assigned Compared to K-means, our new method sited the first 44% of plants at superior locations in terms of local straw density (i.e. lower transportation costs) and the next 39% at equivalent locations. K-means produced better locations for the final 17% of plants along with superior average results. For the smallest facilities at locations defined by 3-year average available straw density, 1.2 km buffers were adequate to provide straw for the first 10% of plants, with twice that distance sufficient for the first 70%. For the largest plants, 12 km buffers satisfied the first 10% of plants, with 24 km buffers satisfying the first 60%. Buffer distances exceeded 68 km for the final 20% of the largest plants. Siting patterns for the smallest plants were more evenly distributed than larger ones, suggesting that farm-scale technology may be more politically appealing. Smaller plants, however, suffered from higher year-to-year variability in straw supply within pre-defined distances. Published in 2010 by John Wiley & Sons, Ltd.