Prospects & potential of biobutanol production integrated with organophilic pervaporation - A techno-economic assessment

The technical feasilibity of integrating ABE fermentations with organophilic pervaporation has been described and demonstrated numerous times. However, engineering guidelines for integration of pervaporation with fermentation are currently not available. A novel calculation procedure to size pervaporation units in function of carbohydrate concentration in the feed is elaborated in detail. The overall energetic and economic outlook are less investigated and remain unclear. Furthermore, the effect of permeate pressure and cooling are frequently ignored. Therefore, the advantages and economic outlook of such an integration are estimated and calculated for fermentative n-butanol production at a capacity of 100 ktonnes per year. Biobutanol production costs for two cases were calculated. The base-case consists of a multi-stage acetone-butanol-ethanol fermentation with default downstream processing. The alternative is a continuous hybrid process where default downstream processing is complemented with organophilic pervaporation for recovery of solvents during the fermentation. Bare pervaporation module costs were estimated to ensure improved economics in comparison to the base-case. Equal installed costs for both cases are reached at a pervaporation module purchase price of 176 (sic) m(-2) for a composite POMS membrane. To derisk this potential large scale organophilic pervaporation application, a module purchase price of 50-100 (sic) m(-2) should be targeted.