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News and Trends
(full access to journal article may require paid subscription) http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V2W-50PB9S6- Researchers from the Institute for Future Energy Consumer Needs and Behavior, Institute for Market Analysis and Agricultural Trade Policy, and the Energy, Transportation and Environment Department (all in Germany) report a "concise, but exhaustive overview of policies that have promoted the rise of the biofuels industry across the world. The major biofuel-producing countries are reviewed individually, taking note of the regulations, incentives, output targets and principal feedstocks used. Analysis of the information was used to identify both the driving forces behind the rise of biofuel production, and the agricultural products that are directly affected. The review of the major biofuel-producing countries are grouped according to continents as follows: North America (Canada, United States of America), South America (Argentina,Brazil, Colombia), Europe (the European Union, France, Germany), Asia (China, India, Indonesia, Malaysia, Thailand) and Australia. Among the conclusions of the review are: (1) government policy has been the driving force for biofuel production, and the key instruments have been mandatory blending targets, and economic incentives; (2) debates regarding the impacts of biofuels on food security and greenhouse gas (GHG) emissions have prompted the initiation of new rules for bioethanol and biodiesel production (for example, the promotion of second-generation biofuel feedstocks); and (3) the issue related to the sustainability of biofuels will challenge policy makers, as biofuels production continues to expand. The full paper is published in the journal, Energy Policy.
(complete access to journal article may require paid subscription) http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V22-50X9S7F- Researchers from the University of Florida (United States) report the use of the Australian Weed Risk Assessment (WRA) system to evaluate the potential invasiveness of certain taxa of biofuel crops in Florida and the United States. "Potential invasiveness" is a not-so-often-mentioned criterion in the selection of bioenergy crops for cultivation and biofuel production. The more commonly mentioned biofuel-crop-cultivation criteria are: (1) high productivity, (2) low input requirements, and (3) wide habitat breadth. Invasion potential is said to be an issue of concern "because of the substantial economic and ecological impacts of plant species that become invasive in new habitats". Thus, it has been recommended that the selection of biofuel crops to be planted in a certain area must include an assessment of potential risk that the species might become invasive. The Australian WRA has been reported to identify invaders 90% of the time, while for non-invaders, 70% of the time. Using this system to test certain bioenergy crop species for cultivation in Florida, the following were found to have a high probability of invasiveness: Jatropha curcas, Eucalyptus grandis, Leucaena leucocephala, Ricinus communis. On the other hand, Miscanthus giganteus, Saccharum officinarum, and a sweet variety of Sorghum bicolor was found to have a low probability for invasiveness. The full paper is published in the journal, Biomass and Bioenergy (URL above) Related information on Australian Weed Risk Assessment (WRA) System: http://plants.ifas.ufl.edu/assessment/pdfs/predictive_tool.pdf Energy Crops and Feedstocks for Biofuels Production
(complete access to journal article may need paid subscription) http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V22-51F8130- "Biomass recalcitrance" is a term given to second-generation (lignocellulosic) biofuel feedstocks which are not easily amenable to the pretreatment processing step in the "cellulose-ethanol" production process. "Recalcitrance" is attributed to the tight lignin wrapping which prevents the accessibility of the biomass carbohydrate fractions (cellulose/hemicellulose). The carbohydrate fractions must be accessible to enzymatic hydrolysis so that these can be converted to simple sugars that are eventually fermented into ethanol. Extreme (and energy-intensive) pretreatment processes (such as high temperature in acidic, alkaline or oxidizing conditions) are often used to break biomass recalcitrance. In order to reduced the high pretreatment costs associated with the pretreatment of recalcitrant biomass, scientist are starting to focus on developing genetically-tailored bioenergy crops with modified lignin contents in the biomass. The lignin modification allows less extreme pretreatment conditions during ethanol processing. An international team of scientists from the United States and China report the use of genetic modification (of a lignin biosynthetic pathway) and "low phytic acid mutation" on barley and wheat straws, in an effort to develop biofuel feedstocks with low biomass recalcitrance. They found that "the change of fiber structure caused by mutation and genetic modification significantly improved "hydrolysibility" of the straws, and further enhanced cellulosic ethanol production". The full paper is published in the journal, Biomass and Bioenergy (URL above)
http://www.biotechnologyforbiofuels.com/content/4/1/1 "Plant cell wall deconstruction" in the production of cellulose-ethanol from lignocellulosic biomass usually involves (1) the removal of the tight lignin wrapping surrounding the carbohydrate (cellulose/hemicellulose) fraction of the biomass; and (2) enzymatically breaking down the cellulose/hemicellulose into simple sugars (by cellulase and hemicellulase enzymes) for fermentation into ethanol. Enzymatic breakdown of cellulose (also called "saccharification" is considered to contribute to the high production cost of ethanol, due to the cost of enzymes. One strategy to decrease the cost of saccharification is to develop plants which already contain cellulose in the biomass (i.e., stalks or leaves). In this way, the feedstock can be made more easily "saccharifiable," as it would require a lesser dose of cellulase. Scientists from the National Renewable Energy Laboratory (United States) report the expression of endoglucanase (a type of cellulase that attacks the inner bonds of the cellulose fibers) in tobacco and maize. They found that the tobacco and maize plants which expressed the endoglucanase became "less recalcitrant" compared to wild-type counterparts, when subjected to enzymatic saccharification. The "reduction in recalcitrance was manifest through lower severity requirements to achieve comparable levels of conversion to wild-type biomass". The full results of the study are published in the open-access journal, Biotechnology for Biofuels (URL above). Related information on cellulases: Biofuels Processing
(complete access to journal article may require paid subscription) http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V22-51HJBFD- Researchers from the Laboratorio Nacional de Ciencia e Tecnologia do Bioetanol, Federal University of Pernambuco, Center of Sugarcane Technology (Brazil) report the use of dilute acid mixtures of sulfuric acid (1%, w/v) and acetic acid (1% w/v) for the pretreatment of sugarcane bagasse. The objective of the pretreatment was to liberate the cellulose and hemicellulose fractions of the biomass, so that these could be easily saccharified to simple sugars. The simple sugars are subsequently fermented to ethanol. The dilute acid mixture treatment was performed at two solids loading ratios of 1.5:10 and 1.0:10(kilograms bagasse to liters dilute acid). The temperature of the reaction mixture was heated to 190 degrees Celsius for 10 minutes. The results showed that at both solids loading conditions, the hydrolysis of hemicellulose was efficient, giving removals greater than 90%. The high yield of hemicellulose hydrolyzates with low (toxic) lignin-degradation products makes this a potentially good substrate for ethanol fermentation. Morphological analyses also showed that the pretreatment process was effective in disrupting the fibers. The full results of the study are published in the journal, Biomass and Bioenergy (URL above). Biofuels Policy and Economics
http://publications.apec.org/publication-detail.php?pub_id=1099 The Asia Pacific Economic Cooperation (APEC) recently released a report on sustainable biofuels development and practices of its member countries. Many APEC economies are aware of both positive and negative impacts of biofuels development. Member countries which are major biofuel consumers are reported to be initiating the use of sustainable criteria (through regulatory or voluntary standards) to screen their biofuels. Even for APEC economies without biofuel sustainability criteria, sustainability issues and the potential impacts on trade, are also being considered. The report contains "current policies, programmes, and practices in APEC economies that aim to ensure that biofuels are sustainable". The report found that many APEC countries are still in the early stages of biofuel development, and activities heavily lean on research/planning. Activities related to monitoring have been observed to be few. Among the recommendations are: (1) collaboration on sustainable biofuels activities and sharing of lessons learned,; (2) promotion of all areas of sustainability simultaneously, rather than looking at a select few elements of sustainability; and (3) Incorporation of more performance-based approaches to monitoring compliance with, and impacts of, sustainable biofuel policies, programs, and practices to ensure that their intended outcomes are realized and negative unintended consequences are addressed. The full APEC Biofuels Development Sustainability report can be downloaded at the APEC website (URL above). |
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