Biofuels in Africa Mitchell, Donald O
2011, 2010, 11-24-2010
eBook, Book
Odprti dostop
Biofuels offer new opportunities for African countries. They can contribute to economic growth, employment, and rural incomes. They can become an important export for some countries and provide ...low-cost fuel for others. There is also a potentially large demand for biofuels to meet the rapidly growing need for local fuel. Abundant natural resources and low-cost labor make producing biofuel feedstock's a viable alternative to traditional crops; and the preferential access available to most African countries to protected markets in industrial countries provides unique export opportunities. Biofuels also bring challenges and risks, including potential land-use conflicts, environmental risks, and heightened concerns about food security. This book examines the potential of African countries to produce biofuels for export or domestic consumption and looks at the policy framework needed. It is part of the effort by the World Bank's Africa region to examine critical issues that affect the region and to recommend policies that effectively address these issues while providing an enabling environment for the private sector. The book is intended to inform policy makers and the larger development community of the global and domestic market opportunities facing biofuel producers, as well as the challenges of producing biofuels, in the Africa region.
Bier ist ein komplexes Stoffgemisch aus Wasser, Ethanol und einer Vielzahl von flüchtigen und nichtflüchtigen geschmacksaktiven Verbindungen. Während der Lagerung kommt es zu chemischen Reaktionen, ...bei denen einige Bestandteile abgebaut und andere neu gebildet werden. Mit dem chemischen Profil verändert sich auch der Geschmack eines Bieres, was zur Alterung und schließlich zum Verderb führen kann. Den Einfluss der Verpackung auf die Lagerstabilität hat kürzlich ein US‐amerikanisches Forscherteam untersucht.
BackgroundSince 2010, commercially available bio-ethanol fuelled burners became increasingly popular in Europe. Unfortunately, the increase in bio-ethanol use resulted in an increase in the number of ...burn injury victims as a result of accidents with bio-ethanol. In 2010 there were 2 victims of accidents with bio-ethanol requiring admission in a Dutch burn centre, whereas this number rose to 29 victims in 2011. To assess what caused this sudden peak in accidents with bio-ethanol, a qualitative exploring research with a interpretative variant was performed.MethodsFirst, field research was conducted. Three experts on bio-ethanol (burners) were questioned in order to construct sensitising concepts as a background for framing the interviews. Second, non steering semi-structured interviews were conducted among 14 victims of a bio-ethanol burn accident. Complete transcripts of the recorded interviews were divided by thematic fragments and coded according to the sensitising concepts. All the identical coded fragments were combined.ResultsBio-ethanol was often misused, that is 8 of the 14 participants used the bio-ethanol as an accelerant for lighting up a fire or barbeque instead of using it for bio-ethanol fuelled burners.All participants had poor knowledge of bio-ethanol use and most participants did not read the conditions of use. Vapour formation in half-full bio-ethanol bottles forms a major risk for an explosion, especially when there is a flame in close proximity when using bio-ethanol. Many of the bio-ethanol bottles were half-full when the accident happened and flames were still in place when using bio-ethanol.ConclusionsBio-ethanol is cheap and easily obtainable, which creates an image of an innocent product. Instead, bio-ethanol is a product with a high risk of accidents when misused. Our outcomes showed that during accidents with bio-ethanol, there was a lack of knowledge, bio-ethanol was used for the wrong purpose and flames were still in place when using bio-ethanol.
Due to increasing population and industrialization, the demand of energy is increasing day by day. Simultaneously, the worldwide bio-ethanol production is increasing constantly. The maize, sugarcane ...and sugar beets are major traditional agricultural crops used as bio-ethanol production but these crops are unable to meet the global demand of bio-ethanol production due to their primary value of food and feed. Hence, cellulosic materials such as agro-residues are attractive feedstock for bio-ethanol production. The cellulosic material is the most abundant biomass and agro-residues on the earth. Bio-ethanol from agro-residues could be a promising technology that involves four processes of pre-treatment, enzymatic hydrolysis, fermentation and distillation. These processes have several challenges and limitations such as biomass transport and handling, and efficient pre-treatment process for removing the lignin from the lignocellulosic agro-residues. Proper pre-treatment process may increase the concentrations of fermentable sugars after enzymatic hydrolysis, thereby improving the efficiency of the whole process. Others, efficient microbes and genetically modified microbes may also enhance the enzymatic hydrolysis. Conversion of cellulose to ethanol requires some new pre-treatment, enzymatic and fermentation technologies, to make the whole process cost effective. In this review, we have discussed about current technologies for sustainable bioethanol production from agro-residues.
Two- and three-body Coulomb explosion dynamics of isolated ethanol dications are studied via single-photon double-ionization with ultrafast extreme-ultraviolet pulses. The measured 3-body momentum ...correlations obtained via 3D coincidence imaging of the ionic products provide evidence for several concerted and sequential mechanisms: (1) a concerted 3-body breakup mechanism, with dominating channels such as CH3+ + COH+ + H2; (2) sequential dissociation in which the ejection of a low-kinetic-energy neutral OH precedes the Coulomb explosion of C2H52+ → CH3+ + CH2+; and (3) a sequential 3-body breakup mechanism that dominates H3+ formation from the ethanol dication via a mechanism that is different from the well-studied H3+ formation in the 2-body Coulomb explosion of the methanol dication. Furthermore, we report surprising branching ratios of the competing C–O bond dissociation channels, resulting in H3O+, H2O+ and OH+ formation.
To further improve the intrinsic reactivity of single-atom catalysts (SACs), the controllable modification of a single site by coordinating with a second neighboring metal atom, developing ...double-atom catalysts (DACs), affords new opportunities. Here we report a catalyst that features two bonded Fe–Co double atoms, which is well represented by an FeCoN6(OH) ensemble with 100% metal dispersion, that work together to switch the reaction mechanism in alcohol dehydrogenation under oxidant-free conditions. Compared with Fe-SAC and Co-SAC, FeCo-DAC displays higher activity performance, yielding the desired products in up to 98% yields. Moreover, a broad diversity of benzyl alcohols and aliphatic alcohols convert into the corresponding dehydrogenated products with excellent yields and high selectivity. The kinetic reaction results show that lower activation energy is obtained by FeCo-DAC than that by Fe-SAC and Co-SAC. Moreover, computational studies demonstrate that the reaction path by DACs is different from that by SACs, providing a rationale for the observed enhancements.
A series of luminescent microporous organic polymers (LMOPs) have been synthesized by a new synthetic methodology through the palladium catalyzed tandem Suzuki-Heck C-C coupling reactions of several ...aromatic halides with potassium vinyltrifluoroborate. These polymers are porous with the BET surface areas from 318 to 693 cm super(2) g super(-1). The formation of conjugated polymers with the incorporation of vinyl groups leads to the fluorescent properties, and the luminescence of LMOPs could be adjusted from blue to green by selecting the aromatic halides and alternating the ratio of monomers. The fluorescence quenching behaviors of these LMOPs by nitroaromatic analytes in ethanol are investigated. It is found that the fluorescence of the polymers can be effectively quenched by picric acid (PA).
Yeast to directly convert cellulose and, especially, the microcrystalline cellulose into bioethanol, was engineered through display of minicellulosomes on the cell surface of Saccharomyces cerevisiae .... The construction and cell surface attachment of cellulosomes were accomplished with two individual miniscaffoldins to increase the display level. All of the cellulases including a celCCA (endoglucanase), a celCCE (cellobiohydrolase), and a Ccel_2454 (β-glucosidase) were cloned from Clostridium cellulolyticum , ensuring the thermal compatibility between cellulose hydrolysis and yeast fermentation. Cellulases and one of miniscaffoldins were secreted by α-factor; thus, the assembly and attachment to anchoring miniscaffoldin were accomplished extracellularly. Immunofluorescence microscopy, flow cytometric analysis (FACS), and cellulosic ethanol fermentation confirmed the successful display of such complex on the yeast surface. Enzyme–enzyme synergy, enzyme-proximity synergy, and cellulose–enzyme–cell synergy were analyzed, and the length of anchoring miniscaffoldin was optimized. The engineered S. cerevisiae was applied in fermentation of carboxymethyl cellulose (CMC), phosphoric acid-swollen cellulose (PASC), or Avicel. It showed a significant hydrolytic activity toward microcrystalline cellulose, with an ethanol titer of 1,412 mg/L. This indicates that simultaneous saccharification and fermentation of crystalline cellulose to ethanol can be accomplished by the yeast, engineered with minicellulosome.
•Seven strategies were employed to produce ethanol from mixed CF and CS.•Three corn to CS ratios were applied for ethanol production from mixed CF and CS.•The performance of different integration ...methods varies with the ratio of CF to CS.•Highest ethanol titer of 99.3 g/L was obtained when the ratio of CF:CS was 20%:10%.•Mixing liquefied CF with 6 h hydrolyzed CS led to the highest ethanol productivity.
This work investigated all possible process integration strategies for ethanol production from corn and dilute acid pretreated corn stover (CS) as mixed substrates. Three corn to pretreated CS ratios (20%:10%, 10%:20% and 5%:25%) were examined. When the ratio of corn to pretreated CS was 20%:10%, the process integration strategy that mixed corn with CS hydrolysate for liquefaction followed by SSF resulted in the highest ethanol titer of 99.3 g/L. Mixing liquefied corn with pretreated CS for hydrolysis/saccharification followed by fermentation was the best strategy for the other two ratios. The strategy of mixing liquefied corn with pretreated CS for 6 h hydrolysis followed by fermentation showed the highest productivity for all the tested ratios.
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