Simulation and comparison of processes for biobutanol production from lignocellulose via ABE fermentation

Abstract

AbstractSix conceptual process scenarios for the production of biobutanol from lignocellulosic biomass through acetone‐butanol‐ethanol (ABE) fermentation, using reported data on process performances, were developed with ASPEN Plus® V8.2 software. The six scenarios covered three fermentation strategies, i.e. batch separate hydrolysis and fermentation (SHF), continuous SHF, and batch simultaneous saccharification and fermentation (SSF) integrated with gas stripping (GS). The two downstream processing options considered were double‐effect distillation (DD) and liquid‐liquid extraction and distillation (LLE&D). It was found that the SSF‐GS/DD scenario was the most energy efficient with a liquid fuel efficiency of 24% and an overall efficiency of 31%. This was also the scenario with the best economic outcome, with an internal rate of return (IRR) of 15% and net present value (NPV) of US$387 million. The SSF‐GS/DD scenario was compared to a similar molasses process, based on the product flow rates, and it was found that the molasses process was more energy efficient with a gross energy value (GEV) of 23 MJ kg1 butanol compared to −117 MJ kg1 butanol for the lignocellulosic process. In addition, the molasses‐based process was more profitable with an IRR of 36% compared to 21%. However, the energy requirements for the molasses process were supplied from fossil fuels, whereas for the lignocellulose processes a portion of the feedstock was diverted to provide process energy. Improved environmental performance is therefore associated with the lignocellulosic process. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd