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News and Trends
http://www.universitynews.org/f2ShowScript.aspx?i=23228&q=Glycerol+Improves+Methane+Production+During+Anaerobic+Digestion Glycerol is a by-product in the making of biodiesel. Although some of the glycerol can be used as raw material in some industries, not all of it can be utilized. A "glycerol-glut" (or "glycerine-glut") is expected when biodiesel operations become commonplace in many countries. Strategies are underway to find other value-added uses of glycerol, in anticipation of this "glycerol-glut". Researchers from the University of Manitoba (Canada) found that glycerol supplementation improves the anaerobic digestion of swine manure. Anaerobic digestion is a biological treatment process where organic matter is degraded by microorganisms (in the absence of air). The process produces another type of gaseous biofuel called, "biogas" (a 55/45 to 60/40 volume mixture of methane and carbon dioxide, under good operating conditions). University of Manitoba graduate student, Oswald Wohlgemut found that an optimum proportion of glycerol (about 1%) doubled the biogas production in swine-manure anaerobic digesters. Glycerol additions greater than 1%, however, caused digester failure. A large-scale pilot project is reportedly being developed at the University of Manitoba's research farm, at Glenlea, "to assess the anaerobic digestion of manure co-mixed with various other waste materials to enhance gas production"..
http://www.worldbioenergy.org/system/files/file/WBA%20PP1,%20Final%202009-11-30.pdf The World Bioenergy Association (WBA) recently released a position paper on the global potentials of biomass energy. The position paper (based on the report by the Department of Energy and Technology at the Swedish University of Agricultural Sciences) says that "the potential to produce biomass for energy in a sustainable way is sufficient to meet global demand. Among the highlights of the position paper are: (1) the total global bioenergy production potential by 2050 (based on a scenario applying "best available technologies") is estimated at 1,548 Exajoules. (A "joule" is a unit of energy, and 1 Exajoule is equal to 1018 joules). On the other hand, global primary energy consumption (on a high end consumption scenario) is lesser and is estimated at 1,041 Exajoules, (2) there are no technical problems seen with respect to shifting the energy mix from fossil fuels to bioenergy; however, efforts to improve overall efficiency must be in place, (3) only about 0.19 percent of the total global land area is devoted to biofuels, while 0.5 percent of total global land area is agricultural land, (4) there is little public awareness on potential of bioenergy, and the establishment of an information/education campaign will be helpful to promote bioenergy, (4) "sustainable development of biomass and biofuel is a major challenge" in increasing biomass production for bioenergy; international efforts to establish "sustainability criteria" to regulate the production and trade of bioenergy are underway. Related Information: World Bioenergy Association http://www.worldbioenergy.org/ Energy Crops and Feedstocks for Biofuels Production
http://www3.interscience.wiley.com/journal/123226769/abstract (may require paid subscription for full access of technical paper) Research by scientists at the Biotechnology Foundation Laboratories, Thomas Jefferson University (United States) can potentially provide a new added-value for the tobacco plant: oil for biodiesel production. Many of the plant oils used for biodiesel production are commonly found in the seeds. The tobacco plant also has a "potent oil biosynthesis machinery", with an ability to accumulate 40% of oil in its seed. However, because the tobacco plant yields only a moderate amount of seeds (only about 600 kg per acre), the Thomas Jefferson University scientists modified the tobacco plant (by metabolic engineering approaches), so that the oil can be overexpressed in the leaves. Two metabolic approaches were explored to enhance the oil content in tobacco leaves: (1) an Arabidopsis thaliana gene diacylglycerol acyltransferase (DGAT) coding for a key enzyme in triacylglycerol (TAG) biosynthesis, was expressed in tobacco under the control of a strong ribulose-biphosphate carboxylase small subunit promoter, and (2) a master regulator of seed maturation and seed oil storage under the control of an inducible Alc promoter was expressed in tobacco Arabidopsis gene LEAFY COTYLEDON 2 (LEC2). The first approach resulted in a 20-fold increase in oil accumulation in the tobacco leaves. In the second approach, "stimulation of LEC2 expression in mature tobacco plants by acetaldehyde led to the accumulation of up to 6.8% per dry weight of total extracted FA (fatty acid)". The research findings are published in the Plant Biotechnology Journal (URL above).. Biofuels Processinghttp://www.biotechnologyforbiofuels.com/content/2/1/31 Scientists from Wageningen University (Netherlands) report the optimization of pretreatment conditions for wheat straw using maleic acid. The findings are published in the open access journal, Biotechnology for Biofuels. Pretreatment is usually the first step in the production of "second generation" bioethanol from lignocellulosic biomass, like wheat straw. It is done "to disrupt the lignin-carbohydrate matrix and to facilitate enzymatic cellulose hydrolysis by improving cellulose accessibility to cellulolytic enzymes". The use of sulfuric acid (a strong inorganic acid) in combination with heat, is a common acid-based preatreatment method. However, some of the sugars produced by this method are converted by a side reaction, into compounds that inhibit ethanol fermentation. Maleic acid (an organic acid) reportedly avoids this undesirable side reaction. A statistical approach via Response Surface Methodology was used. A Central Composite Design was set up with the following process design variables: maleic acid concentration, temperature and pretreatment time. The response factors were: (1) glucose benefits (defined in the paper), (2) xylose benefit (defined in the paper), (3) cost of unrecoverable maleic acid, (4) cost of sodium hydroxide used for neutralization after acid treatment prior to enzymatic hydrolysis, (5) cost arising from furfural formation, (6) heating costs. The process was shown to achieve "almost complete conversion of wheat straw glucan and xylan". Details of the study and full access to the paper can be obtained at the Biotechnology for Biofuels website (URL above).. http://www.biotechnologyforbiofuels.com/articles/browse.asp (provisional pdf version during time of access) Researchers from the Michigan State University (United States) investigated the use of the Ammonia Fiber Expansion (AFEX) process for the pretreatment of switchgrass (Panicum virgatum), at different harvest times and different ecotypes/locations. The AFEX process involves the addition of liquid ammonia into the biomass, at pressures between 100 psi to 400 psi (pounds per square inch) and temperatures between 70 to 200 degrees Celsius. A reactor which is (in many ways) similar to a pressure cooker is used. The pressure is held for some time and then rapidly released. The sudden release in pressure explosively disrupts the lignocellulose fibers, resulting in the breakage of the biomass lignin-carbohydrate matrix, and the release of sugars. Results showed that "each harvest type and location responded differently to AFEX treatment". The least mature sample required the least severe pretreatment conditions (i.e., temperature, pressure, loadings) and had the highest sugar release. The most mature harvest had the least amount of sugar released. Details of the study are published in the open access journal, Biotechnology for Biofuels (URL above).. Biofuels Policy and Economics
The NewEnergyFocus website reports the release of a study on indirect greenhouse gas (GHG) effects of waste/residue bioenergy feedstocks, commissioned by the Department of Energy and Climate Change (DECC) and the Renewable Fuel Agency (RFA) (both in the United Kingdom). The study on "Methodology and Evidence Base on the Indirect Greenhouse Gas Effects of Using Wastes, Residues, and By-products for Biofuels and Bioenergy", had the following objectives: (1) develop a "methodology for quantifying indirect greenhouse gas impacts of using wastes, residues and by-products for biofuels or bioenergy, and (2) provide case studies, applying the developed methodologies, on four "inelastic" bioenergy raw materials: molasses, municipal solid waste, straw and tallow. The report showed that biofuels/bioenergy produced from wastes, residues or by-products can cut greenhouse gas emissions, but if the material has other end markets such as in animal feedstock, it may have negative indirect effects, and could actually see a rise in emissions. Other key findings of the study (as summarized in the NewEnergyFocus website) are: (1) "using municipal solid waste for biogas as a transport fuel would make a net carbon emissions saving of 193% compared with fossil diesel", (2) "the net savings from using tallow biofuels would be 14%". The full report can be accessed at the Renewable Fuels Agency (RFA) website (URL above). Related Information: DECC and RFA websites http://www.decc.gov.uk/ |
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