Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Agroetanol ?un combustible ambientalmente amigable?
Interciencia , 2009,
Abstract: concerns about energetic security and climate change have driven the present boom of agrofuels. unfortunately, their development occurs before appropriate environmental impact studies have been made and a strong debate has been generated. the main arguments against agroethanol are reviewed herein. agrofuels have a positive net energy balance; for sugarcane ethanol it is ~8 while for corn ethanol it is <1.5; in theory, cellulosic ethanol may reach up to 36. co2 emitted by bioethanol combustion does not count as a greenhouse gas; however, during its production such gases are emitted. in the production of corn ethanol there is only a small saving of emissions. the reduction with sugarcane ethanol is very favorable when only gases included in the kyoto protocol are considered; however, when other climate active compounds are considered, co2-eq emission would surpass that produced by equivalent amounts of gasoline. agroethanol production promotes the transformation of natural soils, with loss of biodiversity and enormous co2 emissions. intensive mono-crops promote erosion, pollute waters and decrease productivity and stability of ecosystems. agrofuels compete for arable soils and are, in part, responsible for food price increases. the polemics about genetically engineering organisms will be exacerbated with the increased use of agrofuels. ethanol combustion in vehicles presents some disadvantages to gasoline, does not decrease cancer risk, increases photochemical smog in cities and increases methane emission. the eventual arrival of cellulosic ethanol could improve the situation. however, the present production potential could only replace a small percentage of liquid fossil fuels, maintaining oil dependence.
Effects of enzyme feeding strategy on ethanol yield in fed-batch simultaneous saccharification and fermentation of spruce at high dry matter
Kerstin Hoyer, Mats Galbe, Guido Zacchi
Biotechnology for Biofuels , 2010, DOI: 10.1186/1754-6834-3-14
Abstract: In the present study, SSF was run successfully with 10% and 14% water-insoluble solids (WIS) in batch and fed-batch mode. The mixing of the material in the reactor was significantly better in fed-batch than batch mode, and similarly high or higher ethanol yields were achieved in fed-batch mode compared with batch SSF in some cases. No general trend in the dependence of ethanol yield on enzyme feeding strategy was found.The optimum enzyme feeding strategy appears to depend on the conditions during SSF, such as the WIS concentration and the concentration of inhibitory compounds in the SSF medium.Climate change is one of the greatest challenges of our time. Replacing fossil fuels with so-called biofuels, such as bioethanol, is one way of reducing greenhouse gas emissions from the transport sector, which is responsible for a considerable proportion of total CO2 emissions [1]. Currently, many crops rich in sugar or starch, such as sugarcane, maize and wheat, are used for ethanol production. However, to minimize the environmental effects and the competition between crops for food and fuel production, and to maximize cost efficiency, it is important to consider other raw materials. So-called 'second-generation bioethanol production', using lignocellulosic material such as agricultural or wood residues, is considered a promising approach. In Sweden, the most abundant raw material for ethanol production is softwood, in the form of logging waste and waste from the forest industry [2].Bioethanol can be produced from lignocellulosic material by hydrolysis of the cellulose and hemicellulose to monomeric sugars, followed by fermentation of these sugars to ethanol [1,3]. Performing hydrolysis and fermentation in a single step, the so-called 'simultaneous saccharification and fermentation' (SSF) process, has several advantages over separate saccharification and fermentation (SHF) [4-6]. In SSF, end-product inhibition of β-glucosidase is avoided, and the number of reactors needed in
Spittlebug impacts on sugarcane quality and ethanol production
Ravaneli, Gisele Cristina;Garcia, Débora Branquinho;Madaleno, Leonardo Lucas;Mutton, Miguel ?ngelo;Stupiello, José Paulo;Mutton, Márcia Justino Rossini;
Pesquisa Agropecuária Brasileira , 2011, DOI: 10.1590/S0100-204X2011000200002
Abstract: the objective of this work was to evaluate the impacts of spittlebug (mahanarva fimbriolata) attack on sugarcane quality and ethanol production. technological and microbiological parameters of juice and fermentation process were evaluated in ten fermentation cycles and two harvest seasons. treatments consisted of different spittlebug stalk damage levels: control, with 100% of apparently healthy stalks; medium, with 15% of damaged or dry stalks (dds); high, with 30% of dds; and very high, with 60% of dds. spittlebug attack caused significant losses in cane quality, reducing total soluble solids, sucrose content, total reducing sugars, and ph, and increasing total phenolic compounds, and total and volatile juice acidity. the fermentation process was also significantly affected, resulting in lower ethanol content in wine. there was an increase in acetaldehyde concentration in the distillate. the spittlebug attack caused negative impacts on sugarcane quality and fermentation process, and these impacts are stronger in late season harvests.
The Kyoto Protocol Is Cost-effective
Marino Gatto,Andrea Caizzi,Luca Rizzi,Giulio A. De Leo
Ecology and Society , 2002,
Abstract: Despite recent advances, there is a high degree of uncertainty concerning the climate change that would result from increasing atmospheric greenhouse gas concentrations. Also, opponents of the Kyoto Protocol raised the key objection that reducing emissions would impose an unacceptable economic burden on businesses and consumers. Based on an analysis of alternative scenarios for electricity generation in Italy, we show that if the costs in terms of damage to human health, material goods, agriculture, and the environment caused by greenhouse gas emissions are included in the balance, the economic argument against Kyoto is untenable. Most importantly, the argument holds true even if we exclude global external costs (those due to global warming), and account for local external costs only (such as those due to acidic precipitation and lung diseases resulting from air pollution).
Cellulosic Ethanol Production from Sugarcane Baggase without Enzymatic Saccharification
Raj Boopathy,Letha Dawson
BioResources , 2008,
Abstract: Sugarcane processing generates a large volume of bagasse. Disposal of bagasse is critical for both agricultural profitability and environmental protection. Sugarcane bagasse is a renewable resource that can be used to produce ethanol and many other value added products. In this study, we demonstrate that cane processed bagasse could be used to produce fuel grade ethanol without saccharification. A chemical pre-treatment process using alkaline peroxide and acid hydrolysis was applied to remove lignin, which acts as physical barrier to cellulolytic enzymes. Yeast Saccharomyces cerevisiae ATCC strain 765 was used in the experiment. The pre-treatment process effectively removed lignin. Ethanol production in the culture sample was monitored using high performance liquid chromatography. The results indicate that ethanol can be made from the sugarcane bagasse.
Challenges of the Knowledge Society , 2012,
Abstract: The risks posed by climate change are real and its impacts are already taking place. The biggest challenge about climate change is that there is no one single answer, no one single solution. This characteristic, together with the long history of political frictions and disputes worsened by environmental stresses suggests that global climatic changes have the potential to exacerbate existing international tensions. On December 31, 2012, the Kyoto Protocol's first commitment period will expire. Unless states agree to a second commitment period, requiring a further round of emissions cuts, the Protocol will no longer impose any quantitative limits on states' greenhouse gas emissions. Although, as a legal matter, the Protocol will continue in force, it will be a largely empty shell, doing little if anything to curb global warming. Unlike the Kyoto Protocol negotiations, which focused exclusively on developed country emissions, the ongoing negotiations on a post-2012 climate change regime have also addressed developing country mitigation actions, without which a solution to the climate change problem is impossible. This has made the current negotiations as much between developed and developing countries as between the U.S. and the European Union. Key issues include: Legal Form; Regulatory approach; and Differentiation. By the Durban conference in December 2011 the EU needs to decide whether - and how - it will sign-up to a second commitment period for the Kyoto Protocol. This article focuses on the European Union needs to decide whether – and – how it will sign- up a second commitment period for the Kyoto Protocol. Because asking, whether others will act is the wrong question. The real question is whether signing- up to some form of second Kyoto commitment period will support Europe’s fundamental interests.
Microbiological Saccharification and Ethanol Production from Sugarcane Bagasse
Naureen Chaudhary,Javed I. Qazi
Biotechnology , 2006,
Abstract: Four strains of Bacillus cereus were grown in 5% sugarcane bagasse soaked in water (MI) and 2% bagasse, 0.6% yeast extract, 0.1% (NH4)2SO4, 0.075% MgSO4 and 0.35% KH2PO4 and 0.2 mL of trace element solution comparing of 1.5% EDTA, 0.45% ZnSO4, 0.1% MnCl2, 0.45% CaCl2, 0.3% FeSO4.7H2O and 0.01% KI (M-II). The bacteria showed good growth in both the media. Then these bacteria were optimized for growth conditions in M-III medium comprising of 2% sucrose, 0.6% yeast, 0.1% (NH4)2SO4, 0.075% MgSO4, 0.35% KH2PO4 and 0.2 mL of trace element solution comprising of 1.5% EDTA, 0.45% ZnSO4, 0.1% MnCl2, 0.45% CaCl2, 0.3% FeSO4.7H2O and 0.01% KI. All the four strains grew best at pH 7 and 37°C. Aeration was not required for these bacterial strains. 5% inocula sizes were found optimum for the bacterial isolates except strain No. 23, which yielded best growth with 10% inoculum. After 2nd day of incubation in M-IV medium the bacteria liberated upto 8033 mg/100 mL of total sugar content, which showed reduction in subsequent sampling periods. On the other hand glucose content showed variable response to incubation periods. The strain 11a expressed 1411 mg/100 mL of glucose at 10th day while isolate No. 23 yielded 808 mg/100 mL glucose at 18th day of incubation. Fermentation by ethanologenic yeast of culture fluids saccharification by the isolate 194 and 23 expressed about 0.2 and 1.2% ethanol on 3rd and 7th days, respectively. The bacterial strains were identified as Bacillus cereus based upon their chemical characterization. These isolates appear potential candidates for saccharifying the sugarcane bagasse and production of ethanol employing ethanologenic yeast.
The Kyoto protocol in a global perspective  [cached]
Andreja Cirman,Polona Domadenik,Matja? Koman,Tja?a Redek
Economic and Business Review , 2009,
Abstract: The global climate has changed notably since the beginning of the Industrial Revolution. Atmospheric concentrations of greenhouse gasses (GHG) have increased dramatically followed by an increase in global average temperature. In order to avoid negative potential outcomes of global warming, countries have adopted the United Nations Framework Convention on Climate Change that has so far been ratified by 192 countries. In 1997 the Kyoto Protocol, a binding GHG reduction plan, was adopted and entered into force in 2005. But several countries, including the USA, have had doubts about the potential negative consequences of the planned 5% global joint reduction of GHG. However, studies generally show that on a macroeconomic level: (1) welfare loss in terms of GDP and lost growth in EU is low; (2) it differs among economies; and (3) permit trading and permit price (in either global or regional markets) is highly correlated with the welfare loss. The main objective of the paper is to describe the attitudes and responses to the Kyoto Protocol from a global perspective. The paper has three objectives. First, to provide an overview of global greenhouse gas emissions and the big drivers behind these emissions. Second, to present where different countries, both developed and less developed countries, such as India, China and the countries of South-east Europe currently stand as regards their efforts to achieve the Kyoto Protocol requirements. Third, to analyse the responses and attitudes to the Kyoto Protocol from a country development perspective.
Future prospects for ethanol fuel use - a review
G Ahmed, S Abubakar, NM Ahmed
Bayero Journal of Pure and Applied Sciences , 2009,
Abstract: Countries inspired by a desire to reduce greenhouse gas emissions in order to meet their Kyoto Protocol targets, have turned to ethanol fuels as a cheap and proven alternative to reduce vehicular emissions. Political instability in the Middle East has further motivated countries to develop their own fuel supply to ensure the security of supply and promote internal economic growth. The use of fuel ethanol has attracted considerable negative press and public comments in the early part of 2000s. Because of the importance of ethanol fuel as alternative to petrol, this review presents discussions outlining the various benefits and costs of using fuel ethanol with the objective of highlighting the future prospects of its use to reduce greenhouse gas emissions, provide cheap energy source for vehicles and also provide income to farmers producing bio-ethanol.
Bioconversion of Sugarcane Biomass into Ethanol: An Overview about Composition, Pretreatment Methods, Detoxification of Hydrolysates, Enzymatic Saccharification, and Ethanol Fermentation
Larissa Canilha,Anuj Kumar Chandel,Thais Suzane dos Santos Milessi,Felipe Ant nio Fernandes Antunes,Wagner Luiz da Costa Freitas,Maria das Gra as Almeida Felipe,Silvio Silvério da Silva
Journal of Biomedicine and Biotechnology , 2012, DOI: 10.1155/2012/989572
Abstract: Depleted supplies of fossil fuel, regular price hikes of gasoline, and environmental damage have necessitated the search for economic and eco-benign alternative of gasoline. Ethanol is produced from food/feed-based substrates (grains, sugars, and molasses), and its application as an energy source does not seem fit for long term due to the increasing fuel, food, feed, and other needs. These concerns have enforced to explore the alternative means of cost competitive and sustainable supply of biofuel. Sugarcane residues, sugarcane bagasse (SB), and straw (SS) could be the ideal feedstock for the second-generation (2G) ethanol production. These raw materials are rich in carbohydrates and renewable and do not compete with food/feed demands. However, the efficient bioconversion of SB/SS (efficient pretreatment technology, depolymerization of cellulose, and fermentation of released sugars) remains challenging to commercialize the cellulosic ethanol. Among the technological challenges, robust pretreatment and development of efficient bioconversion process (implicating suitable ethanol producing strains converting pentose and hexose sugars) have a key role to play. This paper aims to review the compositional profile of SB and SS, pretreatment methods of cane biomass, detoxification methods for the purification of hydrolysates, enzymatic hydrolysis, and the fermentation of released sugars for ethanol production.
Page 1 /100
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.