http://www.iea.org/textbase/papers/2008/2nd_Biofuel_Gen.pdf

A report from the IEA (International Energy Agency) analyzes the impacts and limitations of first generation biofuel feedstocks, and the growing interest in the shift toward the use of second generation energy crops.  First-generation feedstocks are generally those which are derived from food sources (such as corn for ethanol and soybean for biodiesel).  These have been found to have “limited capabilities for oil product substitution, and climate change”.  Furthermore, these feedstocks have sustainability issues.  The cultivation of first generation feedstocks may cause “undue competition for land and water used for food/fiber production”.  Interest in the use of second generation (non-food based) feedstocks (such as agricultural residues, vegetative grasses and short-rotation forest trees) have arisen because these are seen to avoid the “concerns facing first generation feedstocks”.  Furthermore, second generation energy crops are said to have a long term cost reduction potential.  The report also analyzes the technical challenges that must be hurdled in industrial biofuel production from second generation feedstocks, and the current policies to support their development.  The full report can be obtained at the IEA website (URL above).

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http://www.aocs.org/news/story.cfm?id=824
http://www.ceres.net/
http://www.bladeenergy.com/

An American company, Ceres, has announced the launching of its first seed sales for “dedicated energy crops” for switchgrass and high-biomass sweet sorghum. “Dedicated energy crops” can be considered as “non-food, low-carbon crops developed specifically as raw materials for biofuels”. The seeds are marketed under the “Blade Crops” label. Switchgrass and sweet sorghum are considered cost-effective and “sustainable” feedstocks for ethanol production. Among its positive features are: low agricultural inputs, capability for cultivation in marginal lands, and good energy/carbon balances. According to Anna Rath, vice president for commercial development, “Switchgrass and high-biomass sorghum can provide new options for growers, especially on under-performing acres”. There are two seed products for switchgrass and high-biomass sweet sorghum seed products available. More information can be obtained at the Ceres of Blade Crops website (URL above).

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http://www.biodieselmagazine.com/article.jsp?article_id=3169
http://pubs.acs.org/doi/abs/10.1021/ef800740d (may require paid subscription for full access)

The Biofuel Magazine website reports that scientists from the National Institute of Standards and Technology (United States) have developed a “method to accelerate stability testing of biodiesel fuel and identified additives that enhance stability at high temperatures”. The factors that affect the stability of a biodiesel product are oxidation and heating. Usually, the evaluation of oxidative and thermal stability is done separately. The new method allows the evaluation of both at the same time. According to NIST scientist, Thomas J. Bruno, the “advanced distillation curve method” could accelerate and simplify testing of biodiesels”. Additionally, the new method was also used to “demonstrate the effectiveness of three additives in reducing oxidation of biodiesel at high temperatures, as would occur in aviation fuels”. The research results involving the use of the new method are published in the journal, “Energy and Fuels” (URL above)..

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http://repositories.cdlib.org/cgi/viewcontent.cgi?article=7997&context=lbnl

Butanol (a 4-carbon alcohol) is considered an “advanced biofuel”, and is reported to have better biofuel features compared to its 2-carbon relative, ethanol. Although butanol has better energy density, better transportability in existing pipeline structures, and can be used in unmodified vehicles at higher blends (compared to ethanol), there are still some bottlenecks for industrial scale production. Butanol is mainly produced by bacteria of the genus Clostridium, under anaerobic conditions. Bacterial production of butanol by Clostridia is not considered a good method because of slow bacterial growth, bacterial toxicity toward the butanol product at 1% to 2% concentrations, and production of significant quantities of unwanted by-products such as acetone. On the other hand, Saccharomyces cerevisiae, the yeast commonly used for ethanol production, grows faster, has a higher alcohol tolerance and produces relatively less unwanted by-products. Scientists from the University of California Berkeley attempted to metabolically engineer Saccharomyces cerevisiae with an n-butanol biosynthetic pathway, in which isozymes from a number of different organisms were substituted with Clostridial enzymes. They evaluated the effect of the substitution on n-butanol production. Results showed that expression of the genes encoding the butyryl-CoA dehydrogenase from C. beijerinckii did not improve butanol production significantly. The problematic steps in the n-butanol biosynthetic pathway and those which could be taken for future improvement were identified..