(731d) Land Allocation in a Sustainable Landscape and a Comparative Life Cycle Assessment of Distributed Vs. Centralized Biorefinery Pre-Processing Systems
AIChE Annual Meeting
Friday, November 12, 2010 - 9:45am to 10:10am
Cellulosic biofuels are a potentially large scale, environmentally superior alternative to petroleum-derived fuels. However, in order to produce large quantities of cellulosic biofuels, biorefineries handling enormous tonnages of a large variety of feedstocks are required and in such conditions a consistent and safe supply of feedstocks becomes critical. Under current thinking, biorefineries are fully integrated operations in which all processes (e.g. size reduction, pretreatment, hydrolysis, fermentation, distillation) of biomass conversion to fuels are present in a single centralized location. This implies contracting with literally thousands of individual farmers, interrupted feedstock supplies, large transport and storage costs of feedstock and other business and market power issues. We believe these and other drawbacks of fully integrated biorefineries can be addressed by network of facilities called ?Regional Biomass Processing Depots? (RBPDs) which could bridge the gap between feedstock suppliers and biorefineries. In its simplest configuration, an RBPD would procure feedstock, pre-process/pre-treat it, densify it and deliver it to the biorefinery in an arrangement that satisfies the biorefinery requirements and return by-products to the appropriate end-user. We envision RBPDs that are configured to provide benefits in all three major sustainability criteria: environmental, economic and social. Specifically, the aim of this study is to allocate land usage in a landscape to various feedstocks based on their sustainability and ethanol/animal feed-yield characteristics, to estimate the total energy consumption and emissions generated due to the operation of the system that consists of feedstock suppliers, animal farms, the RBPD and all related transportation activities and to assess the sustainability of this distributed processing system by performing a comparative Life Cycle Assessment and weighing it against a fully integrated and centralized biorefinery. The study also includes several sensitivity analyses using parameters like yields of grasses, forms of densification and transport energy and emission comparisons using different transport models like GREET and IBSAL. Multiple landscape scales and locations are incorporated in order to evaluate the effect of site-selection and size on the entire system.