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News and Trends
A Purdue University (United States) new release reports that their scientists have "found the last undiscovered gene responsible for the production of the amino acid phenylalanine, a discovery that could lead to processes to control the amino acid to boost plants' nutritional values and produce better biofuel feedstocks". Phenylalanine is an amino acid which is said to be important for the production of flower scent, anti-oxidants, and lignin (a component of plant cell walls which contributes to rigidity and structural integrity of the plant). From the biofuels production point of view, the interest in the discovery of this gene is in the possible development of "tailored bioenergy crops" with low lignin content. A low-lignin feedstock can lower the cost of cellulose ethanol production, by decreasing the pretreatment requirements necessary for delignification. "Decreasing phenylalanine could lead to a reduction in lignin, which would improve digestibility of cellulosic materials for ethanol production". On the other side, increasing phenylalanine could boost the nutritional value of some foods. A technical paper reporting the findings are published in the Nature Chemical Biology Journal (URL above).
http://www.navy.mil/search/display.asp?story_id=57298 The United States Navy reports a test flight by a MH60S Sea Hawk helicopter, powered by fuel blended with 50% camelina-based biofuel. Camelina is a plant, belonging to the family that includes rapeseed and mustard. It is considered a "second generation biofuel feetstock". The helicopter test flight is part of an effort by the US Navy to decrease its need for petroleum-based fuels. Earlier this year, they flight-tested the biofuel blend on an F/A-18 Super Hornet, and found that "the aircraft performed as expected through its full flight envelope with no degradation of capability". The present test flight is reported to be "another step toward the certification of fuels from non-petroleum sources for use in all Navy and Marine Corps aircraft". There are plans to test the camelina biofuel on additional aircraft models in 2011 with a target of approving the 50% biofuel blend in navy ships and aircraft by 2012. Energy Crops and Feedstocks for Biofuels Production
Scientists from the University of Copenhagen (Denmark) report a study on the variation of sugar yields due to genotypic qualities of wheat feedstock during the processing to cellulose ethanol under pilot-plant conditions. Five different wheat cultivars undergoing pilot-scale pretreatment/saccharification were compared in terms of sugar yield and response to enzyme loadings and particle-size distribution. The results of their study confirmed that the optimum parameters for biomass processing to cellulose ethanol can be highly dependent on the cultivar. They found that the effect of cultivar (depending on experimental conditions), was either highly significant or the interaction between cultivar and enzyme loading was significant. Thus, in the breeding of potential feedstocks for biofuel ethanol production, the "processability" of the feedstock to fermentable sugars may be an important consideration. The full paper is published in the open-access journal, Biotechnology for Biofuels.
http://www.sciencedaily.com/releases/2010/11/101110141531.htm The Science Daily website reports a comparative study by Iowa State University (United States) on the single and double cropping of sorghum for biofuel production. They designed experiments on 12 varieties of sorghum grown in single and double cropping systems, and assessed the yields for biofuel production. The study is published in the Agronomy Journal (URL above). The study showed that a single-cropping system was more effective for the production of ethanol. According to researcher and senior author, Ben Goffe, growing sorghum as a sole crop is more efficient for ethanol production, from a production point of view. However, "it remains to be seen whether the favorable long-term environmental benefits, such as reduced erosion potential, of the double-cropping systems merits the reduced total biomass production". Goffe recommends further studies on the double cropping systems, focusing on strategies to maximize sorghum production, such as incorporating a winter crop that matures earlier in the season. Biofuels Processing
Pretreatment of lignocellulosic biomass (usually by chemical methods with heat) is an important step in the cellulose ethanol production process, in order to remove the tough lignin coating in the biomass, and to expose the cellulose/hemicellulose fibers for subsequent saccharification and ethanol production. Due to the "harsh" pretreatment conditions (for example highly acidic or highly basic, plus heat), toxic by-products (which adversely affect/inhibit ethanol-fermentating organisms) are produced. These toxic products include furan derivatives (furfural, 5-hydromethylfurfural [HMF]), organic acids (acetic, formic, or ferulic acids), and lignin derivatives (guiacol, phenol, vanillin). Detoxification steps to remove these by-products are usually necessary after pretreatment. Present detoxification procedures involving physico-chemical methods have been observed to have disadavantages which include high water use/wastewater generation, sugar loss, and inefficient removal of inhibitors. Scientists from East China University of Science and Technology report the use of a fungal strain, Amorphotheca resinae ZN1, to detoxify stover biomass after dilute sulfuric acid or stream explosion pretreatments. Their study showed that "biodetoxification by A. resinae ZN1 provided a fast and efficient biodetoxification method for removing toxins generated during intensive lignocellulose pretreatment". They mentioned some advantages of biological detoxification, including: "zero energy input, zero wastewater generation, and complete toxin degradation". The complete study is published in the open-access journal, Biotechnology for Biofuels.
http://www.biotechnologyforbiofuels.com/content/pdf/1754-6834-3-24.pdf The main raw materials for ethanol fermentation in lignocellulosic biomass are the sugars that are liberated after pretreatment and saccharification of cellulose/hemicellulose fibers. These sugars are commonly fermented to ethanol, using yeasts (Saccharomyces cerevisiae), which have been historically used for ethanol fermentation from saccharine substrates. However, only the hexoses (or six-carbon sugars), like glucose, are utilized by traditional yeast strains. The pentoses (five-carbon sugars), such as xylose and arabinose, are left unutilized, because yeasts have no natural capability to metabolize pentoses. Effective fermentation performance must involve the conversion of both pentoses and hexoses into ethanol. Recent advances in metabolic engineering have been successful in developing yeast strains with pentose-metabolizing capabilities. However, "major difficulties still remain for engineering simultaneous, exogenous sugar metabolism". Scientists from the Department of Chemical Engineering, The University of Texas at Austin (United States), review the issues related to effective pentose utilization in yeasts. Their review highlights the need to shift focus "towards nontraditional aspects of cellular engineering such as host molecular transport capability, catabolite sensing and stress response mechanisms". They termed a new approach called "panmetabolic engineering", as a new paradigm for integrating new carbon sources into host metabolic pathways. The approach is seen to simultaneously optimize "the interdependent processes of transport and metabolism using novel combinatorial techniques and global cellular engineering". The review is published in the open-access journal, Biotechnology for Biofuels (URL above). Biofuels Policy and Economics
http://www.agriculture.gov.ie/press/pressreleases/2010/november/title,48912,en.html The Minister for Agriculture, Fisheries and Food of Ireland, Brendan Smith, recently announced the 2011 Bioenergy Scheme to grant aid for the planting of willow and miscanthus crops. Willow and miscanthus are considered "second generation feedstocks" for biofuel production. The scheme is implemented, pursuant to the European Commision's Regulation (No. 1698/2005 of 20 September 2005) on support for rural development by the European Agricultural Fund for Rural Development (EAFRD). According to the Irish government's agriculture website, the Bioenergy Scheme: (1) provides establishment grants to farmers to grow miscanthus and willow for the production of biomass suitable for use as a renewable source of energy, (2) aims to increase the production of willow and miscanthus in Ireland, and to encourage alternative land use options. Under the scheme, "aid is payable on 50% of the approved costs associated with establishing the crop, subject to a maximum payment rate of €1,300 per hectare, with the balance to be invested by the applicant". Qualified applicants include landowners or those who have leasehold title to the land and have responsibility for farming the land on which it is proposed to carry out the plantation. |
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