COMPARATIVE SYSTEM ANALYSIS OF CARBON PRESERVING FERMENTATIONS FOR BIOFUEL PRODUCTION Report from an f 3 project

PREFACE This project was funded by the Swedish knowledge centre for renewable transportation fuels, f3 (Fossil Free Fuels). The f3 centre is a Swedish nationwide centre that contributes to the development of sustainable transportation fuels by initiating research projects and syntheses of current research. In this final report from the research project entitled " Carbon preserving fermentation " , focusing on the production of 1-butanol. Luleå University of Technology, Lund University and SEKAB have been active partners. A reference group has reviewed the material presented in this report and provided valuable feedback to the authors. The members of the reference group are listed below. (2013) Comparative system analysis of carbon preserving fermentations for biofuel production. SUMMARY Today it is mutual understanding that we need to find replacements for the crude oil and natural gas in order to produce fuel and valuable chemicals even in the future. In Sweden, we are able to reduce the environmental impact and use of fossil raw material by improving the use of biomass from the forest and other origin. New systems for conversion of biomass at the Swedish pulp and paper mills, power plants among other constitute the foundation for an alternative development into a sustainable society. Fuel production from biomass has largely been focused on ethanol production. Limitations in type of raw material required for ethanol production at the large plants made butanol to a very good complement. Butanol has better fuel properties than ethanol both regarding energy content as well as handling. The established production and distribution of ethanol can be shared for cost efficient production. Recently published data suggest that a combined plant with both etha-nol and butanol production by fermentation is economically attractive. The traditional and ones again interesting butanol (ABE) fermentation has a general low yield and releases carbon dioxide. The bacterial strains that are used in butanol fermentations can on the other hand utilize the sugars released from hemicellulose. Hemicellulose represents today the largest fraction of waste at the ethanol plants. Hemicellulose is also the wood component that can be easily extracted from waste generated by the forest industry. We have in this study chosen to investigate the possibility to produce butanol via a novel hybrid process to reduce the raw material need and increase the yield of butanol. In the proposed process the conversion of biomass are made in two steps, first a fermentation that consumes carbon dioxide …