Participants from the f3 project Comparative system analysis of carbon preserving fermentation for biofuel production have recently published an article in Bioresource Technology (vol 161, pp 263-269):
Nilsson, R., Bauer, F., Mesfun, S., Hulteberg, C., Lundgren, J., Wännström, S., Rova, U. & Berglund, K. (2014), Techno-economics of carbon preserving butanol production using a combined fermentative and catalytic approach.