BIOFUELS SUPPLEMENT
---------------------------------------------------------------------------
A bi-weekly summary of world developments on biofuels, produced by the Global Knowledge Center on Crop Biotechnology, International Service for the Acquisition of Agri-biotech Applications SEAsiaCenter (ISAAA)
---------------------------------------------------------------------------
June 25, 2010
In This Issue:
News and Trends
- Analysis of Biofuel Combustion Chemistry Reported
- Key Gene to Overcome Microbial Limitations in Cellulosic Ethanol Production
Biofuels Processing
- New "Robust" Starch Liquefaction Enzyme for Biofuels Production
Biofuels Policy and Economics
- USDA Releases Biofuels Roadmap to Achieve 2020 Renewable Energy Standard
- USDA Releases Updated Corn-Ethanol Energy Balance Calculations
* NEWS AND TRENDS *
Analysis of Biofuel Combustion Chemistry Reported
(full access to journal article may require paid subscription) http://www3.interscience.wiley.com/journal/123411017/abstract
http://www.ncbi.nlm.nih.gov/pubmed/20446278
http://www.internetchemie.info/news/2010/may10/biofuel-combustion-chemistry.html
The internetchemistry website reports some highlights of a scientific article entitled, "Biofuel combustion chemistry: from ethanol to biodiesel", which appears in the 2010 May issue of the journal, Angewandte Chemie (URL above). The paper analyzes the "combustion chemistry of compounds that constitute typical biofuels, including alcohols, ethers and esters". The research, conducted by an international team of scientists, offers detailed insights into how biofuel chemicals react when burned. Although much of biofuels research dwell on the production aspects, fuel delivery structure, engine performance and policy related issues (i.e. food-versus-fuel debate or life-cycle analysis), the combustion chemistry of the compounds that constitute typical biofuels, including alcohols, ethers, and esters, has not received similar public attention.
The review paper "highlights some characteristic aspects of the chemical pathways in the combustion of prototypical representatives of potential biofuels." Discussion focuses on "the decomposition and oxidation mechanisms and the formation of undesired, harmful, or toxic emissions, with an emphasis on transportation fuels." New insights into the highly diverse and complex chemical reaction networks of biofuel combustion were also made possible by novel scientific tools. According to the abstract of the article, "Understanding key elements of this chemistry is an important step towards intelligent selection of next-generation alternative fuels."
Researchers at the Oak Ridge National Laboratory's Bioenergy Research Center (United States) announced that they have identified a Zymomonas mobilis gene which could hold a key for more effective microbial utilization of pretreated lignocellulosic biomass for biofuel-ethanol production. Before lignocellulosic biomass (such as corn stover or switchgrass) can be processed for ethanol fermentation, it undergoes pretreatment "to loosen the cellular structure enough to extract the sugar from cellulose." According to co-researcher, Steven Brown, these treatments add new challenges because, although they are necessary, they create a range of chemicals known as inhibitors that stall or stop (ethanol-fermenting) microorganisms like Zymomonas mobilis from performing the fermentation. Acetic acid (or acetate) is one such inhibitor.
By using the tools of systems biology, the scientists were able to characterize a mutant of Zymomonas mobilis (AcR) and demonstrated that acetate tolerance has potential importance in biofuel development. The researchers developed a strain of Z. mobilis which becomes acetate-tolerant when the key gene is over-expressed; they also found that the mutant gene created a similar impact when it was inserted into yeast. The full paper is published as an open access article in the Proceedings of the National Academy of Sciences (PNAS) (URL above).
The United States Department of Agriculture (USDA) recently released its "Regional Roadmap to Meet the Biofuels Goals of the Renewable Fuels Standard by 2022". It is a comprehensive strategy "to address barriers related to the development of a successful biofuels market that will achieve, or surpass, the current U.S. Renewable Fuels Standards (RFS2)." The goal of the congressionally-mandated RFS2 is to "use at least 36 billion gallons of bio-based transportation fuels by 2022", for the reduction of greenhouse gas emissions. Corn ethanol will constitute a portion of the 36-billion-gallon target, amounting to about 15 billion gallons. Of the remaining 21 billion gallons of advanced biofuels needed to achieve the total 36 billion gallon goal, 16 billion gallons is required to come from advanced cellulosic biofuels (fuels made from cellulosic feedstocks) that also reduce greenhouse gas emissions by at least 60 percent relative to gasoline."
A partial breakdown according to feedstock is as follows: (a) 13.4 billion gallons from including perennial grasses, energy cane, and biomass sorghum; (b) 500 million gallons from oilseed crops, (c) 4.3 billion gallons from crop residues (corn stover, straw), and (d) 2.8 billion gallons from woody biomass (logging residues only). The biofuels digest website mentions that the USDA report "did not include projections on feedstock capacity from municipal solid waste, animal fats and yellow crease, or algae — although it reported that the EPA (in its own projections) has projected 100 million gallons from algae, 380 million gallons from animal residues, 2.6 billon gallons from municipal waste (MSW) and 2.2 billion gallons from imported fuels". The full USDA report can be downloaded at the biofuels digest website (URL above).