Global R&D on production of butanol and use as a transport fuel
The USDA ARS has carried out studies showing that barley straw and corn stover can be converted to butanol with high efficiency via Separate Hydrolysis, Fermentation and Recovery (SHFR) or by Simultaneous Saccharification, Fermentation and Recovery (SSFR). Gas stripping can be used to recover high yields of butanol from the SSFR process [Source, Quereshi et al, ARS Bioenergy Research Unit]. See also Closing In on Butanol for Biofuel.
Butalco GmBH, Switzerland is developing new production processes for biobutanol based on genetically optimised yeasts together with partners in downstream processing technologies.
Optinol has developed a "patented non-GMO clostridium strain that naturally and prolifically favours the production of butanol, without acetone or ethanol". The technique has been developed by researchers at Louisiana State University, US. Optinol says the method can produce butanol at cost parity with bioethanol.
In August 2013, The United States Department of Agriculture (USDA) awarded Microvi Biotechnologies a grant to "develop a breakthrough technology to dramatically improve the yield and performance of biobutanol processes. The technology overcomes toxic and inhibitory effects on butanol producing microorganisms, a major bottleneck in scaling existing biobutanol processes." [Source: Microvi website].
The Wass Research Group, University of Bristol, UK, is developing improved catalysts with yields of 95% offering lower-cost conversion of ethanol to butanol, and potentially enabling ethanol producers to avoid high retrofit costs. Researchers now plan to scale-up the current lab technology as a first step towards commercialisation [Ref: Catalytic Conversion of Ethanol into an Advanced Biofuel: Unprecedented Selectivity for n-Butanol, Prof. Duncan F. Wass etal, Angewandte Chemie International Edition, Volume 52, Issue 34, pages 9005–9008, August 19, 2013].
University of Michigan is developing a method for butanol production from cellulosic plant material using a combination of Trichoderma reesei and E. coli in a bioreactor. See 'Design and characterization of synthetic fungal-bacterial consortia for direct production of isobutanol from cellulosic biomass', Proceedings of the National Academy of Sciences [19 August 2013].
Archive 'research notes' on biobutanol production
It was reported that State corporation, Russian Technologies, will begin construction of a biobutanol factory in the Irkutsk region in spring 2011. The factory will use wood chips and other timber byproducts [Source: Moscow Times].
In the 1980s, hydrolyzates of lignocellulosic material were used to produce butanol on an industrial scale in Russia, and the processes developed have also attracted renewed interest from butanol researchers (the technology pathway for the new biobutanol factory was not mentioned in the news release).
In November 2009, researchers at UCLA announced that modified strains of Synechococcus elongatus could produce isobutyraldehyde and isobutanol directly from carbon dioxide [Source: Nature Biotechnology 27].
Research was also being carried out into the production of 2,3 butanediol (a potential biofuel) from agricultural residues (e.g. hydrolysis of hemicellulose-rich fractions by Trichoderma harzianum followed by fermentations using Klebsiella pneumoniae). Improved fermentation efficiency was one of the focuses of the FP7 SUPRABIO project.
Various biobutanol researchers are working with modified Clostridium strains.
Hydrolysis of cellulosic raw materials prior to butanol conversion potentially offers greatly increased yields. In research published by the USDA in 2007, wheat straw was hydrolyzed to lignocellulosic component sugars (glucose, xylose, arabinose, galactose, and mannose) prior to their conversion to butanol, by Clostridium beijerinckii P260. The rate of production of wheat straw hydrolysate to butanol was 214% over that from glucose.
Ongoing genetic research focused on 'gene knock-out' systems in Clostridium strains, whereby the enzymes that catalyse competing reactions (which produce Acetone, Ethanol, etc) are 'removed'.
Research into the ABE fermentation process has addressed issues of end-product inhibition and control of phage infection, but this technology has now been superceded by more advanced biotechnology, which are now being demonstrated at commercial-scale (as described above).