(534e) Combined Biochemical and Thermochemical Processing of Lignocellulosic Biomass: Techno-Economic Evaluation

The need for environmentally friendly fuels and commodity chemicals has driven research in the production of biofuels and bio-derived chemicals. There is now a broad product portfolio and wide variety of stand-alone technological pathways for biomass conversion systems. In the biochemical pathway of ethanol production alone, there exists multiple conversion technologies available. One such method, the consolidated bioprocessing proposed by Brethauer and Studer [1], seems to offer a viable alternative, as high conversion rates are achieved while combining into one reactor the hydrolysis and fermentation steps. This method of using a microbial consortium for conversion would likely open pathways to other liquid fuels and commodity chemicals as well, as similar work has been done in the production of higher carbon alcohols [2]. But, analogous to an oil refinery, a stand-alone biorefinery must look at coupling heat integration, fuel production, and higher value co-product production. However, work has not yet been widely published to determine feasibility or economic potential for this method of ethanol production. Similarly, scale-up potential and feasibility studies are limited for many of these novel processes.

Moreover, many of these concepts are still in the development stage, which requires the use of process modeling techniques. Modelling of lab-scale based production processes allows for techno-economic analysis and optimization, as estimates of energetic efficiency and scale-up potential of novel conversion processes are lacking. Production feasibility will be highly dependent on the energetic efficiency, environmental sustainability, and economic potential of these bio-based fuels and chemicals, especially in comparison to their fossil-fuel derived counterparts.

This work presents techno-economic process models, using flowsheeting software, of co-production of value added products, liquid fuels, and heat from lignocellulosic feedstock to analyze and compare the annual costs and efficiencies of the different combined biochemical and thermochemical conversion pathways. Furthermore, to contribute to the development and implementation of sustainable biorefineries, a systematic methodology which combines process modeling and optimization approaches is applied and a comparison of the pathways based on economic and energetic efficiencies is then proposed. The results provide a powerful support for the design of biorefinery systems with improved process economics and reduced environmental impact.