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The main objective of this review paper is analyzes perspectives of manufacturing bioethanol via biotechnology, using sustainable management. Two categories are emphasized: (i) agro-industrial valuation, which represents alternative methods for bioethanol production, and (ii) Agro-industrial Techniques and Infrastructure Analysis. Future of biofuels is addressed in terms of applicability and production methods. Authors perform a systematic literature review to characterize the present state of knowledge on ethanol production. The study is conducted from a decision-making standpoint, so that they identify several problems (subcategories) in bioethanol production. The section on technology and industrial infrastructure focuses on advances in biorefineries, revealing technical and economic limitations, and also the gap between sustainable production policies and environmental impact. The second part of the paper presents the evolution of the industrial sector toward technological innovation and adoption of complex bio-production methods for clean energy production. This review mostly covers results reported over the past decade, with a special emphasis on papers published recently, from 2010 to 2021, therefore, it can serve for extended future research that would address additional specific categories. One concludes that the industrial sector must promote bioethanol production efficiently and sustainably, harmonized with the society and the environment. Sustainable production points to alternative energy sources based on cellulosic materials and third generation materials derived from algal biomass. • Chemical processes in the agro-industrial production sector include clean technologies. • Critical gaps for biofuel production contain factors that must be related to industrial processes and uncertain economic cost. • Technological integration of 1G and 2G bioethanol production can reduce operating costs and investment risks. • Biorefinery models use various biomass feedstocks, and they integrate 1st/2nd generation technological processes. [ABSTRACT FROM AUTHOR]

Ethanol production and the diffusion of flex-fuel vehicles are successful examples of renewable energy in the transportation sector in Brazil. Despite these achievements, challenges regarding the Brazilian fleet, composed of inefficient light-duty passenger vehicles (LDPV), need to be addressed. In this regard, political measures have been implemented, for instance voluntary labeling and fiscal incentives related to fuel economy targets. However, there is still room to improve these instruments to capture greater economic and environmental benefits related to fuel economy. In this paper, we present information regarding the Brazilian LDPV fleet, its fuel consumption, its CO 2 emissions and a description of the historical evolution of policies concerning fuel economy in Brazil. Furthermore, we estimate impacts related to the adoption of mandatory fuel economy standards (MFES), in terms of fuel economy and CO 2 emissions reduction. This analysis indicates that 18,626 million liters of gasohol E-22 and 16,274 million liters of ethanol E-100 can be saved up to 2035. The related reduction of CO 2 emissions is also significant, about 62 Gg of CO 2 . [ABSTRACT FROM AUTHOR]

Brown algae adsorb a considerable amount of CO 2 and store carbon in their biomass more than many other algae species. Nowadays, depletion of fossil fuel resources, greenhouse gas emissions, climate change, and the future of human food security have encouraged scientists and policymakers to develop safer and more sustainable alternatives of energy sources. Brown algae have attracted most of this attention in North American countries to generate a wide range of products and biomass for biorefinery. In this review paper, various aspects of brown algae cultivation and its biorefinery process are discussed. Main drivers of the sectors, opportunities, challenges, and future prospects of brown algae-based biofuels in North America have been taken into account; the most appropriate processes and pathways are compared to maximize the outputs and environmental benefits, and minimize costs and drawbacks of the industry. Analysis and predictions of renewable energy future in North American countries revealed that biomass-derived fuels, including brown algae biofuels, will play an important role especially in the transportation sector. These biofuels, including bioethanol and biodiesel are accompanied by various co-products and by-products in an optimized biorefinery system to convert every available component of brown algae. However, cultivation of brown algae to produce biomass at a commercial scale with minimum costs and market demands are the main challenges of algal biofuels. Finally, expanding the value chain of the brown algae biorefinery by producing more advanced biofuels such as aviation fuels and value-added co- and by-products would significantly impact North American countries' gross domestic product. • Many studies related to biofuel production from brown algae are reviewed comprehensively. • Brown algae have attracted significant attention in North America. • Costs and markets demands are two main challenges for this algal energy. • Effective strategies for optimal production of biofuel from brown algae are provided. • Current challenges and future prospects for biofuel from brown algae are discussed. [ABSTRACT FROM AUTHOR]

Bioethanol is an attractive biofuel having potential for energy security and environmental safety over fossil fuels. To date, numerous biomass resources have been investigated for bioethanol production, which can broadly be classified into sugars, starch and lignocellulosic biomass. However, conversion of biomass into ethanol varies considerably depending on the nature of feedstock, primarily due to the variation in biochemical composition, and so, only a few feedstocks have been exploited commercially. In recent years, the conversion process of biomass has been improved significantly, even though most of these achievements are yet to be implemented in commercial facility. All the major steps in a typical conversion process, particularly fermentation of sugars that is the common step for all biomass, are greatly influenced by microorganisms. A traditional yeast, Saccharomyces cerevisiae , and a bacterial species, Zymomonas mobilis , are widely used in the ethanol fermentation technology. Many factors affect ethanol production process, and the final yield is directly associated with the optimum conditions of these attributes. This review paper presents an overview on the first and second generation bioethanol production with a particular attention to the potential of various biomass sources, technological approaches, role of microorganisms and factors affecting ethanol production process. [ABSTRACT FROM AUTHOR]

The potential for sugarcane ethanol from Brazil to mitigate GHG emissions is undeniable, but the way that ethanol is produced during the agricultural and industrial phases will ultimately determine its benefits to society. In this paper, we evaluate the environmental impacts of sugarcane agriculture and ethanol production in Brazil as management practices continue to change and production expands to new frontiers. We focused our evaluation on the impacts on water, atmosphere, and soils, including how the application of organic and inorganic fertilizers and the accumulation of crop residue in the field affect emissions of greenhouse gases (GHG). We also addressed the impacts of land use changes on threatened biomes and discussed some of the present obstacles regarding conservation and restoration efforts. We concluded that, since a similar assessment was put forth in 2008, our knowledge about the environmental impacts of sugarcane ethanol in Brazil has advanced with regard to soil degradation, nitrogen dynamics, and soil carbon stocks. However, more information is still needed about the impacts of the increasing use of pesticides, herbicides, and fertilizers in sugarcane agriculture, especially on water resources. Furthermore, without a better understanding about how landscape fragmentation affects the biodiversity of terrestrial and aquatic tropical ecosystems and the services they provide, policies created to protect and restore them may be ineffective. On the other hand, the use of presently available scientific information to end unsustainable farming and the implementation of conservation strategies proposed by the Brazilian Forest Code could be a first step to guarantee that ethanol is produced more sustainably in Brazil. [ABSTRACT FROM AUTHOR]

The rise of biofuels took place after the great oil crisis that impacted the world in the 70s. At that period, the mission of supplying the world׳s demand was given primarily to liquid biofuels. South America has a set of renewable energy sources and shows a great potential to contribute to the energy supply of the world in the coming years. Brazil leads the production of biofuels in South and Latin America since the 60s and also stands out at a global scale. Considering this context, this paper aims to approach the current scenario and the prospects of the main South-American countries, whose energy matrices receive relevant contribution from liquid biofuels. In South America, liquid biofuels stand out among renewable energies, represented mostly by ethanol and biodiesel. Brazil and Argentina lead the scenario and prospects of these biofuels in South America, while countries like Peru and Uruguay look for alternatives to supply such demands as they struggle internally for legislations that stimulate the use of biofuels in the energy matrix. [ABSTRACT FROM AUTHOR]

Abstract: The contribution of Renewable Energy Resources is vital for a country׳s economic growth by providing high efficiency in energy, as well as an effective tool for the confrontation of climate change. In particular, concerning the EU, an increase in the consumption of Renewable Energy Resources as a proportion of the total energy consumption by its member states was set as an objective until 2020. Ethanol has been widely used as a substitute to conventional energy like gasoline and oil. The present paper surveys the role of alternative energy prices and gas emissions in the formation of the ethanol prices. The results of the empirical survey confirmed the existence of a sole relationship among the variables employed. According to the results obtained, an increase in the volume of emissions or in gasoline prices results in an increase in ethanol prices while the opposite is confirmed in the case of crude oil. Τhe elasticity of ethanol prices to the increase of the emissions is another result worth mentioning, indicative of the significant role of the emissions in the formation of ethanol prices. [Copyright &y& Elsevier]

Abstract: In recent years, algae-based fuels have received a growing interest of the industry sector and the US Government as a sustainable and renewable energy source. Algae constitute a unique feedstock as they contain high levels of both lipids and sugars and, thus, can be used for both biodiesel and ethanol production successively, in a two-stage process. In addition, the production of algae-based fuels shows a low environmental footprint and high energy efficiency. Algae can produce between 10 and 100 times more oil per acre as compared with traditional oil crops (e.g., oil palm) and can also grow 20–30 times faster than food crops. The production of algae does not compete with traditional crops for fresh water, high quality soil or fertilizers and, if cultivated off-shore, algae production does not require land resources at all. Furthermore, algae-based fuel is carbon-neutral, as algae assimilate similar amounts of CO2 for its growth as is released upon fuel combustion. From the policy perspective, algae-based fuels can provide a buffer for mitigating the food/feed vs. fuel problem in the long-term. The paper analyzes and discusses very recent developments in the algae R&D from the economic, environmental and policy perspective. It presents ways for solving the economic impediments as well as prospects for the commercialization of the algae technology in the near future. It covers multiple scientific and industry-related research and experimental studies to provide a comprehensive picture of the trends and patterns in the field. [Copyright &y& Elsevier]

Abstract: With industrial development growing rapidly, there is a need for environmentally sustainable energy sources. Ethanol from biomass, bioethanol, is an attractive, sustainable energy fuel source for transportation. Based on the premise that fuel bioethanol can contribute to a cleaner environment and with the implementation of environmental protection laws in many countries, demand for this fuel is increasing. Efficient ethanol production is based on optimized processes where utilization of cheap substrates is highly demanding. Utilization of different types of lignocellulosic materials can be considered for production of ethanol. Among various types of lignocellulosic substances water hyacinth (Eichhornia crassipes) is a potential resource available in many tropical regions of the world. It is a noxious aquatic weed which grows fast. A considerable amount of research work is in progress for its bioconversion into ethanol using two-sequential steps of hydrolysis and fermentation. This paper reviews the bioconversion of water hyacinth to ethanol. [Copyright &y& Elsevier]

Abstract: In the contemporary era of looming energy crunch, hydrogen fuel, obtained from ethanol, is a potentially strong contender as an energy carrier, based on a renewable source. Moreover, acknowledging the critical importance of distributed power devices and systems on one hand and the importance of microscale engineering on the other, we envisage developing an ethanol-based distributed hydrogen production device of the order of 1kW using steam reforming of ethanol (SRE). In this paper, the key issues related to this microscale distributed hydrogen production strategy are discussed in view of its potential application for polymer electrolyte membrane (PEM) fuel cells. The design challenges and issues related to various essential micro-devices, viz., the pre-heater, fuel reformer, water gas shift (WGS) reactor, carbon monoxide preferential oxidation (CO PrOX), required for efficient production of H2 with very low concentration of CO contamination, are discussed. Various production schemes are carefully evaluated for the purpose. Need for integration of micro-devices is emphasized to obtain a compact fuel processor system. [Copyright &y& Elsevier]

Abstract: This article aims to investigate the introduction, sustenance and consolidation of bioethanol in Brazil. It presents an analysis of its introductory stage, from the first decades of the 20th century until the early 1970s, when, in a second stage, additional measures allowed for its consolidation and maturity, under the widely known Proalcool. The paper presents a historical reinterpretation of the policies, mechanisms and instruments adopted in both stages, aiming to highlight the economical and political links. It is concluded that the interests of the agrarian elites, operating at the political level, and the fuel supply crisis during Second World War were basic during the first stage, to sustain a productive and logistic capacity and maintain ethanol alive as an automotive fuel. It is also concluded that the launching of Proalcool represented a transition combining the interests of the sugarcane agribusiness, burdened by the drop in sugar prices, and the need to equilibrate the balance of payments due to the oil shocks of the 1970s. Ethanol supply shocks harmed its credibility and its commercial consolidation was only possible through the introduction of flex-fuel vehicles with expectations strongly relying on climate change mitigation actions. [Copyright &y& Elsevier]

Abstract: Several biofuel candidates were proposed to displace fossil fuels in order to eliminate the vulnerability of energy sector. Biodiesel and bioethanol produced from terrestrial plants have attracted the attention of the world as potential substitute. However, due to food vs. fuel competition as well as land consumption of these biofuel, they have brought much controversy and debate on their sustainability. In this respect, cultivation of macroalgae such as seaweed at sea water which does not expend arable land and fertilizers provides a possible solution for this energy issue. Carbohydrates derived from seaweeds contain hexose sugars which are suitable materials for fermentation to produce ethanol. Therefore, it is possible to produce fuel ethanol from seaweeds. The potential and prospective of seaweeds to play the role as a sustainable energy provider are demonstrated in this paper. This study offers a conceivable picture of macroalgae-based third-generation bioethanol biorefinery to stimulate the initiation of the exploration in the related field. [Copyright &y& Elsevier]

Abstract: The Autonomous Province of Vojvodina is an Autonomous Province in Serbia, containing about 27% of its total population according to the 2002 Census. Contribution of renewable energy sources in total energy consumption of Vojvodina contemporary amounts to less than 1%, apropos 280GWh/year. By combining of methods of introduction of new and renewable sources, systematic application of methods for increasing of energetic efficacy, as well as of introduction of the new technologies, percentage of contribution of the non-conventional energy sources in Vojvodina could be increased to as much as 20%. This paper presents the potential of development of bioethanol production in Vojvodina. Production of bioethanol on small farms can be successfully applied for processing of only 30kg of corn per day, with obtaining of crude ethanol in the so-called “brandy ladle” and use of lygnocellulosic agricultural wastes as an energy source. In a case of construction of a larger number of such plants, the only possible solution is seen in the principle of construction of the so-called “satellite plants”, which will on small farm produce crude ethanol, with obtaining and consumption of stillage for animal feeding, and consumption of agricultural wastes as energetic fuels. If stillage is to be used as feed in wet feeding, it is estimated that, because of restrictions established by the magnitude of animal farm, the upper limit of capacity of such enterprises that process is at some 10–15tons of corn per day, and production of 3000–3500hL of absolute ethanol per day. In such a case, for animal feeding necessary is to have herd with 1300–1700 of milking cows or 5000–25,000 heads of sheep and/or pigs. Technological model of separate grain processing ad bioethanol production from dextrose hydrolysates of starch is interesting for countries possessing plants for bioethanol production from molasses and plants for cereals processing into starch and dextrose hydrolysates of starch. [Copyright &y& Elsevier]

Abstract: This paper evaluates life cycle energy analysis of molasses based ethanol (MOE) in Nepal. Net energy value (NEV), net renewable energy value (NREV) and energy yield ratio are used to evaluate the energy balance of MOE in Nepal. Total energy requirements in sugarcane farming, cane milling and ethanol conversion processes are estimated and energy allocation is made between co-products (molasses and sugar) as per their market prices. The result shows negative NEV (−13.05MJ/L), positive NREV (18.36MJ/L) and energy yield ratio (7.47). The higher positive value of NREV and energy yield ratio reveal that a low amount of fossil fuels are required to produce 1L of MOE. However, negative NEV reveals that the total energy consumption (both fossil and renewables) to produce the ethanol is higher than its final energy content. Nevertheless, the renewable energy contribution amounts to 91.7% of total energy requirements. The effect of the increased price of molasses and reduced energy consumption in the sugarcane milling and ethanol conversion are found to be significant in determining the energy values and yield ratio of MOE. In addition, there are clear measures that can be taken to improve efficiency along the production chain. Finally, energy security, scarcity of hard currency for importing fossil fuels and opportunities for regional development are also strong reasons for considering local renewable energy options in developing countries. [Copyright &y& Elsevier]

Abstract: Biofuel use seems to have certain environmental, energy and socioeconomic advantages versus fossil fuel consumption. The substitution of fossil fuels with biofuels can be a useful tool to fulfil the Spanish and European policy in relation to mitigation of greenhouse gas (GHG) emissions and increase the security in energy supply. The continuous increase in energy consumption, dependence on energy and high petroleum prices has motivated increasing support for renewable energy promotion. In Spain (the third ethanol producer in Europe in 2007), ethanol from lignocellulosic feedstocks could be one of the most valuable and interesting possibilities for renewable transportation fuels due to the limited competition with food production and high net reduction of GHG emissions. This study is focused on flax shives, obtained as an agricultural co-product from flax crops dedicated to fibre production for specialty paper pulp manufacture as lignocellulosic biomass to produce second generation ethanol involving the use of cellulosic technology. The life cycle assessment (LCA) methodology was used to evaluate the environmental impacts of the production and use in a flexi fuel vehicle (FFV) of ethanol blends (10 and 85% in volume of ethanol with gasoline) versus conventional gasoline, throughout their whole life cycle in order to highlight the main sources of these impacts. The system boundaries include cultivation, extraction, processing and final use of fuels. Mass and economic allocation were considered to determine the effect on the results of different allocation approaches. The results of the study show that the allocation methods are essential for outcomes and decision-making. Using ethanol as transportation fuel could present better environmental performance than conventional gasoline in terms of global warming and fossil fuel consumption according to mass allocation. However, environmental credits could be achieved in terms of acidification, fossil fuel consumption and human toxicity according to economic allocation. Contributions to other impact categories such as eutrophication and photochemical oxidants formation were lower for conventional gasoline regardless of the allocation procedure selected. Agricultural activities related to feedstock production are notable contributors to the environmental performance. Thus, high yielding varieties, reduction of tillage activities and reduction in fertilization should help to reduce these impacts. [Copyright &y& Elsevier]

Abstract: Due to the high energy-importing dependence (98%) and tremendous greenhouse gases (GHGs) emission (over 13metric tons/capita-year), the diversification of kinds and sources of primary fuel like petroleum is making vital energy and environmental issues in Taiwan. In this regard, bioethanol fuel from energy crops has thus become attractive in this subtropical/tropical nation due to the rampant increase in oil price and governmental policies on promoting bioethanol as a potential substitute for gasoline fuel in recent years. The objective of this paper is to present an analysis of bioethanol fuel produced from sugar crops as one of the gasoline additives in the transportation sector of Taiwan. The analytical description in the manuscript is thus summarized on current energy supply and its future supply goal, and gasoline supply and consumption during the years of 1990–2005. It is emphasized that bioethanol was ever produced commercially from sugar manufacturing by-product (i.e., molasses) for more than 50 years in Taiwan. Concerning the promotion of bioethanol production, the description centered on new/revised promotion regulations/policies for the measures of agricultural sustainability, environmental protection, energy management, and financial incentives. Finally, we analyze the safety, health, and environmental risk of using bioethanol fuel, and also address its preliminary benefits on an industrial scale of 500,000kiloliters/year from a cane field of 100,000ha, showing a total energy output of 3.0×107 GJ/year and a CO2 mitigation of 7.5×105 metric tons/year. [Copyright &y& Elsevier]