In this study conceptual process designs were simulated in ASPEN
PLUS in order to compare different possible process routes for
industrial scale biobutanol production from sugarcane molasses in
South Africa. Process Design 3, using the fermentation strain C. beijerinckii
BA 101 in fed-batch fermentation with in situ gas stripping
followed by LLE and steam stripping distillation, was the only profitable
process design under current economic conditions, and was
able to compete with the petrochemical pathway for butanol production.
The first order estimate of the TPCC for this design was $
190 m for a production capacity of 118,800 ton butanol per annum,
resulting in attractive economic indicators (IRR: 36%; NPV $960 m).
Process Designs 3 also had a favorable energy performance position
(NEV was a large positive and ER was larger than 1), thereby
producing a product with more energy than is required for the production
process. However using molasses as the only feedstock
could result in large fluctuations in the biobutanol