Techno-economic assessment of gasification as a process step within biomass-to-liquid (BtL) fuel and chemicals production

This study investigates the gasification process step which converts a biomass derived intermediate called slurry into synthesis gas (syngas) for subsequent synthesis of fuel and chemicals. The slurry is produced by fast pyrolysis plants and is then processed in a pressurized entrained flow gasifier. The resulting syngas has to be conditioned and cleaned before it is converted in a Fischer-Tropsch or dimethyl ether synthesis in order to complete a biomass-to-liquid (BtL) production such as the considered bioliq concept. This two-stage concept allows the economic transportation of biomass over long distances, due to the relatively high energy density of the slurry produced in the first stage. In addition, reductions in specific investments and costs for further processing in the second stage are enabled by economies of scale. This paper addresses possibilities for further process development and presents an outlook for a commercial implementation of a biomass derived slurry gasification. Within the techno-economic assessment, different process configurations for the gasification facility are analysed using an Aspen Plus process model and compared from an economic and energetic point of view. The varying process parameters are operating pressure, gasification agent, syngas composition as well as feedstock composition. The techno-economic assessment concludes that it is possible to produce syngas at costs of about 23(sic)-Cent/Nm(3) based only on biomass feedstock. The production costs can almost be cut by half when considering co-gasification of biomass and coal. Further higher operating pressures of the gasification process are identified as a major influence on production costs reduction. The potential effects of marketing by-products such as excess heat as well as excess nitrogen are also addresses in this study. (C) 2011 Elsevier B.V. All rights reserved.