18-20: Integration of biorefineries into conventional facilities: environmental and techno-economic assessment under uncertainty

Tuesday, May 1, 2012
Napoleon Ballroom C-D, 3rd fl (Sheraton New Orleans)
Juan David Villegas and Edgard Gnansounou, Bioenergy and Energy Planning Research Group (BPE), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland

The carbohydrate fraction of lignocellulosic biomass can be refined into food and fuel products and the remaining lignin-rich residue used as source of heat and power. Adding value to lignocellulosic agricultural residues is a promising option of sustainable use of a largely underutilized resource. However, increasing demand for biorefinery products can be constrained by availability of the required feedstock (with suitable quality and composition). Moreover, biorefineries’ time-to-market is highly uncertain.   Cost-efficiency of process stages such as pretreatment, saccharification and valorization of hemicelluloses need to be improved. Gradual introduction of novel biorefinery pathways into established, large-scale food and energy pathways can benefit of economies of scale and synergistic design of process units. Two main scenarios were evaluated:

The first scenario consists in a facility located in a tropical developing country, refining sugarcane bagasse (Saccharum spp.) and green harvesting residues (GHR). While bagasse was traditionally used as source of heat and power in sugar-mills and ethanol refineries, GHR was left on the field after harvesting sugarcane without previous field burning.

Second scenario’s plant is located in an industrialized country endowed with reduced land availability.  Ethanol and feed molasses production from wheat straw is integrated into conventional wheat (Triticum aestivum L.) grain production and large-scale, multi-feedstock co-generation units. A combined techno-economic and life cycle assessment (LCA) assessment was performed. The assessment considered competitive uses of biomass, uncertainty on future performances of technology and feedstock supply, and efficacy of system’s multi-functionality.  Different process integration schemes, including various pretreatment alternatives were evaluated for both scenarios.

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