Search

The valorisation of the organic fraction of municipal solid waste (OFMSW) in the circular economy context is of outmost importance. This review aimed to examine the state-of-the-art valorisation technologies of OFMSW as resource for bioethanol and biodiesel. Firstly, feedstock mapping was performed, where high fluctuation of parameters was revealed. Considering the mean values, the stoichiometries of mechanically and source-sorted OFMSW are C 22 H 44 O 28 N and C 20 H 36 O 16 N, respectively. The substrate's mean carbohydrates (50%) and lipids (13%) contents reflect its potential in bioethanol and biodiesel production, respectively. As far as bioethanol is concerned, this paper critically reviewed the existing variance of second-generation bioethanol production methodologies from OFMSW revealing that high bioethanol yields (over 80%) could be achieved if the treatment steps of pretreatment, enzymatic hydrolysis and fermentation are synergistically compiled. To this end, bioethanol yield could benefit from suitable enzymatic blends. Furthermore, this paper discussed about different ways of oil extraction from OFMSW and various biodiesel production techniques. Soxhlet extraction combined with alkaline transesterification emerged as the most widely applied biodiesel production line from OFMSW. The novelty of this literature review lies in the integration of both bioethanol and biodiesel production processes, in a biorefinery concept that would allow the production of both biofuels along with that of biogas. This integration scenario rendered an energy efficiency expressed as energy content in products per energy in raw materials equal to 68%, proving that OFMSW is a feedstock that could meet the sustainability criteria for biofuels production. Image 1 • Up to date information on the composition of OFMSW. • Bioethanol production from OFMSW; pretreatment, hydrolysis, fermentation, stillage. • Biodiesel production from OFMSW; oil extraction, transesterification. • Bioethanol, biodiesel, biogas production from OFMSW under the biorefinery concept. • Integrated biorefinery exhibits various technical and energy benefits. [ABSTRACT FROM AUTHOR]

Abstract The acid pretreatment process is the most employed technique used to disrupt the lignocellulosic matrix. Thus, this paper provides an overview of the acid pretreatment considering important aspects related to the operation conditions, yields, future improvements and the potential use to upgrade lignocellulosic biomass in energy vectors. Moreover, this paper is focused on technical and economic aspects of the use of the acid pretreatment in bioethanol production using olive tree biomass as a case study. This review will provide the framework of the acid pretreatment based on reported applications, experimental and theoretical data. The most well-studied applications of the acid pretreatment are in bioethanol and biogas production. Furthermore, this pretreatment has been improved using solid catalysts and by increasing the solids loading. These options have advantages compared to the traditional way. Even so, improvements in the technical and energy aspects must be performed to make the implementation of this process viable from an economic and environmental perspective. Instead, the kinetic modelling and statistical analysis of the acid pretreatment can be postulated as strong tools to predict the behaviour of different feedstocks under acidic conditions. Moreover, new alternatives to increase the mass and heat transfer in this process related to reactor design conform a new research field. Regarding the case study, the acid pretreatment is one of the most energy-consuming stages of bioethanol production. Low solids loadings are recommended to obtain production costs that are comparable with those reported on the industrial level. In contrast, a high solids loading allows the environmental impact of the process to be reduced in terms of liquid waste generation and carbon dioxide emissions. Finally, the acid pretreatment should be included as an effective method for the biotechnological conversion of lignocellulosic biomass to produce energy vectors once the technical, economic and environmental drawbacks have been overcome. Highlights • Energy vectors production can be improved using optimal acid pretreatment operating conditions. • Operation conditions and kinetic modelling are shown as key information of the acid pretreatment. • Solid catalyst and dry acid pretreatment can serve as alternative methods for biomass upgrading. • The impact of solids loading on the bioethanol production process is demonstrated and discussed. • Low solids loading in acid pretreatment increases the feasibility of bioethanol production. [ABSTRACT FROM AUTHOR]

The recent and rapidly growing interest in biofuel as a green energy source has raised concerns about its impact on the prices, returns and volatility of related agricultural commodities. Analyzing the spillover effects on agricultural commodities and biofuel helps commodity suppliers hedge their portfolios, and manage the risk and co-risk of their biofuel and agricultural commodities. There have been many papers concerned with analyzing crude oil and agricultural commodities separately. The purpose of this paper is to examine the volatility spillovers for spot and futures returns on bio-ethanol and related agricultural commodities, specifically corn and sugarcane. The diagonal BEKK model is used as it is the only multivariate conditional volatility model with well-established regularity conditions and known asymptotic properties. The daily data used are from 31 October 2005 to 14 January 2015. The empirical results show that, in 2 of 6 cases for the spot market, there were significant negative co-volatility spillover effects: specifically, corn on subsequent sugarcane co-volatility with corn, and sugarcane on subsequent corn co-volatility with sugarcane. In the other 4 cases, there are no significant co-volatility spillover effects. There are significant positive co-volatility spillover effects in all 6 cases, namely between corn and sugarcane, corn and ethanol, and sugarcane and ethanol, and vice-versa, for each of the three pairs of commodities. It is clear that the futures prices of bio-ethanol and the two agricultural commodities, corn and sugarcane, have stronger co-volatility spillovers than their spot price counterparts. These empirical results suggest that the bio-ethanol and agricultural commodities should be considered as viable futures products in financial portfolios for risk management. [ABSTRACT FROM AUTHOR]

Grasses as lignocellulose biomass are promising feed stocks for renewable bioethanol production, since these raw materials have high productivity, require low agricultural inputs, have positive environmental impacts, are easy to process and do not compete with the food crops. However, bioethanol production from grass biomass requires efficient pre-treatment, enzymatic hydrolysis and microbial fermentation processes which varies with types of grass species and the microorganisms used. Pretreatment is an important process for delignification of lignocellulose biomass and is dependent on the type of lignin present in the biomass and the degradation pathway employed for removal of the specific type of lignin. Further, enzymatic hydrolysis converts the cellulose and hemicellulose into monomers, making it feasible for the fermenting microorganisms to convert it into bioethanol where use of improved strain and biomass can yield higher ethanol on industrial scale. This review paper presents an overview of the types of grass species, their composition and cultivation practices, fermentation process used for bioethanol production and genetic tools used for improvement in bioethanol production from grass biomass on a sustainable basis. The current knowledge and future prospect for industrial bioethanol production from grass biomass along with its economic aspects have also been discussed in this review. [ABSTRACT FROM AUTHOR]

This paper propose the inclusion of a raw material in Brazilian fuels sector. The corn is used in other countries to produce ethanol, in Brazil has other business demands, not being employed as proposed. The work also highlights the energy, economic, social and environmental role in production ethanol from corn, especially for the country´s development, minimizing losses in logistics and grain exports. Comparatively corn is more expressive as bioenergy associated with sugarcane in the Brazilian conditions, because other raw materials have limitations: sugar beet does not have viable cultivation; rice, cassava and wheat are insufficient; and sweet sorghum requires technological adjustments to have significant production. The co-products that arise from the production of ethanol are nutritionally rich, causing less pressure on corn commodities trading. [ABSTRACT FROM AUTHOR]

The possible scarcity of oil and gas resources in the future (whether in quantity or areas of availability) is a major concern throughout the world. For this reason, governments all over the world are working on reducing their dependence on imported energy resources. Alternative energy resources such as bioethanol, biodiesel and biomass have gained prominence over the years in order to substitute petroleum-derived products. Bio-based lubricants have also gained importance as alternatives to conventional petroleum-based lubricants in various applications, especially the automotive industry. Despite the benefits of bio-based lubricants, these lubricants are still far from being practical substitutes. Since bio-based lubricants are typically produced from raw vegetable oils, these lubricants have poor cold flow properties as well as low thermo-oxidation and hydrolytic stability. However, these shortcomings can be addressed by modifying the vegetable oils chemically or incorporating additives into the oils. This review provides a detailed treatment on bio-based lubricants, the various vegetable oils used as the feedstocks for the production of bio-based lubricants, the physicochemical properties of bio-based lubricants, the processes used for chemical modification of vegetable oils, the lubrication properties of bio-based lubricants, as well as the various additives used to improve the properties of bio-based lubricants. It is believed that this review paper will provide useful insight to researchers and practioners in the field regarding bio-based lubricants. [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]

Abstract: While biofuels have currently been regarded as a good alternative for fossil fuels, there remain many debates on their impacts on human and environment. This paper tried to shed light on bio-ethanol in Brazil as one of the main producers and exporters in the world. The main question was to understand “how sustainable is bio-ethanol production in Brazil?” To answer, the political motives of producing bio-ethanol followed by its ecological and socio-economic impacts were discussed. The paper concluded that although bio-ethanol production in Brazil seems environmentally friendly, it might socio-economically be hazardous. [Copyright &y& Elsevier]

Bioethanol is one of the most promising and eco-friendly alternatives to fossil fuels, which is produced from renewable sources. Although almost all the current fuel ethanol is generated from edible sources (sugars and starch), lignocellulosic biomass (LCB) has drawn much attention in recent times. However, the conversion efficiency as well as ethanol yield of the biomass differs greatly with respect to the source and nature of LCB, primarily due to the variation in lignocellulosic content. Two major polysaccharides in LCB, namely, cellulose and hemicellulose firmly link to lignin and form a complex lignocellulosic network, which is highly robust and recalcitrant to depolymerization. For this reason, generation of ethanol from LCB requires a complicated conversion process that has made it commercially non-competitive. As attempts to exploit LCBs into commercial ethanol production, recent research efforts have been devoted to the techno-economic improvements of the overall conversion process, in addition to screen out promising feedstocks. This review paper presents an overview on the diversity of biomass, technological approaches and microbial contribution to the conversion of LCB into ethanol. [ABSTRACT FROM AUTHOR]

Increased environmental concern over climate change due to higher oil usage has made human being to shift to cleaner and greener alternatives. The utilization of abundant agricultural waste streams as renewable feedstock for biofuels production can be a pivotal strategy. Among others, rice is one of the most largely grown crops, and more than 4.8% of the total production goes to waste. Although previous reviews are related to biofuels obtained from some rice waste, most of those are focused on lignocellulosic rice residues with much attention to thermo-chemical processes. The present paper, instead, reviews for the first time the biotechnological approaches to convert all rice wastes, like rice husk, rice straw, broken rice, discolored rice, unripe rice, into liquid (bioethanol, biobutanol, biodiesel), and gaseous (biogas, biohydrogen) biofuels through the use of pure or mixed microbial cultures. The global availability of each rice byproduct has been also investigated and the potential of rice waste as a 'fuel farm' has been estimated for bioethanol. The physical, chemical, enzymatic, or microbial pretreatments, which play a key role in making carbon available for hydrolysis and fermentation, are here discussed and evaluated. Despite the great promise of technologies so far developed, further research is still required for their up-scale and industrial commercialization. Moreover, future process integrations will open the landscape to biorefinery schemes where rice waste streams can be processed into biofuels and other added-value products, towards the full exploitation of the feedstocks and the economic and environmental sustainability of the overall process. [Display omitted] • Rice waste has the potential to produce many gigalitres of biofuels worldwide. • Selection of pretreatment is the key to obtain the highest biofuel production. • Different biotechnological approaches for biofuel production are elucidated. • Complete rice waste valorization using a biorefinery approach is underscored. [ABSTRACT FROM AUTHOR]

Industrial technologies for bioethanol production from lignocellulosic biomass were reviewed by integrating feedstock handling, selective-fractionation, synergistic enzymatic hydrolysis, industrial fermenting yeast strains, and simultaneous saccharification and co-fermentation in this paper. The breakthrough of integrated technologies contributed to economic feasibility was also analyzed by industrial operation test. With the integrated technologies, the feedstock cost was reduced by 19.4% compared with traditional conversion process. The enzyme loading was reduced by 25.0% using synergistic enzyme systems compared with single cellulase addition. The pre-hydrolysis and simultaneous saccharification and co-fermentation without detoxification operation was developed using inhibitors-tolerant Saccharomyces cerevisiae . More than 4% (w/w) ethanol concentration was achieved, which corresponded to 72.3% theoretical yield of ethanol. The improved conversion efficiency of pentose resulted in 41% increase of ethanol yield. Additionally, lignin plastic composite material (LPCM) and compress natural gas (CNG) were co-produced, which proportioned the capital cost of process and hence facilitated the economic feasibility of process. As a result, the corresponding ethanol total cost was reduced to 5571.6 Yuan/t (Yuan, Chinese currency). In conclusion, the low cost of feedstock, simple and integrated conversion process, and multi-products production contribute to the competiveness of this integrated industrial technology for lignocellulosic bioethanol production. [ABSTRACT FROM AUTHOR]

Fuel cell systems powered by bio-fuels such as ethanol are potential solutions to local, small scale electricity needs, especially in remote, off-grid locations. In recent years, many researchers around the world have studied the on-site autothermal reforming of ethanol to hydrogen, which can then be used in the fuel cell. However, a comprehensive review of those efforts has not been carried out. In this paper, a detailed literature review of experimental and numerical research is presented, with a focus on the catalysts, reactor design, and simulation and modelling efforts that sought to understand interactions among fluid flow, heat and mass transfer and chemical kinetics. Our review indicates that although considerable work has been carried out on the development of catalysts, relatively fewer studies report system level experiments and simulations that are necessary before these systems can be commercially deployed. Thereby, we also identify areas for further research in the area of ethanol autothtermal reforming. [ABSTRACT FROM AUTHOR]

The aim of the current paper is to discuss the sustainability aspect of biorefinery systems with focus on biomass supply chains, processing of biomass feedstocks in biorefinery platforms and sustainability assessment methodologies. From the stand point of sustainability, it is important to optimize the agricultural production system and minimize the related environmental impacts at the farming system level. These impacts are primarily related to agri-chemical inputs and the related undesired environmental emissions and to the repercussions from biomass production. At the same time, the biorefineries need a year-round supply of biomass and about 40–60% of the total operating cost of a typical biorefinery is related to the feedstocks chosen, and thus highlights on the careful prioritization of feedstocks mainly based on their economic and environmental loadings. Regarding the processing in biorefinery platforms, chemical composition of biomasses is important. Biomasses with higher concentrations of cellulose and hemicelluloses compared to lignin are preferred for bioethanol production in the lignocellulosic biorefinery, since the biodegradability of cellulose is higher than lignin. A green biorefinery platform enables the extraction of protein from grasses, producing an important alternative to importing protein sources for food products and animal feed, while also allowing processing of residues to deliver bioethanol. Currently, there are several approaches to integrate biorefinery platforms, which are aimed to enhance their economic and environmental sustainability. Regarding sustainability assessment, the complexities related to the material flows in a biorefinery and the delivery of alternative biobased products means dealing with multiple indicators in the decision-making process to enable comparisons of alternatives. Life Cycle Assessment is regarded as one of the most relevant tools to assess the environmental hotspots in the biomass supply chains, at processing stages and also to support in the prioritization of any specific biobased products and the alternatives delivered from biorefineries. [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: Pretreatment technologies are aimed to increase enzyme accessibility to biomass and yields of fermentable sugars. In general, pretreatment methods fall into four different categories including physical, chemical, physico-chemical, and biological. This paper comprehensively reviews the lignocellulosic wastes to bioethanol process with a focus on pretreatment methods, their mechanisms, advantages and disadvantages as well as the combinations of different pretreatment technologies. Moreover, the new advances in plant “omics” and genetic engineering approaches to increase cellulose composition, reduce cellulose crystallinity, produce hydrolases and protein modules disrupting plant cell wall substrates, and modify lignin structure in plants have also been expansively presented. [Copyright &y& Elsevier]

Abstract: Contribution to satisfying the final energy demand, the necessities arises from waste minimization, and rural area's developments are the main incentives for biofuel usage in the Iranian energy supply system. This paper develops a model for the supply chain of bioethanol and bioETBE from the farms to the end users which integrates the temporal and spatial scales. It considers the techno-economical evaluations of first and second generation biofuels. The results provide practical insights for decision makers to introduce the biofuel into the Iranian energy systems. Here, the optimal designs of transition pathways of biofuel supply chain are available which successfully assesses the benefits and barriers to the decision maker. [Copyright &y& Elsevier]

Abstract: This paper aims at reviewing the life cycle assessment (LCA) literature on second generation bioethanol based on lignocellulosic biomass and at identifying issues to be resolved for good LCA practice. Reviews are carried out on respective LCA studies published over the last six years. We use the classification of lignocellulosic biomass to define system boundaries, so that the comparison among LCA results can be thoroughly assessed based on identified system components. A basis for attributing environmental burden for different biomass feedstocks is also suggested. Despite the non-homogeneous systems, we conclude that second generation bioethanol performs better than fossil fuel at least for the two most studied impact categories, net energy output and global warming. For the latter category, carbon sequestration at the biomass generation stage can even consistently offset the GHG emissions from all parts of the life cycle chains at high ethanol percentage (≥85%). The aspect of biogenic carbon and agrochemical input for energy crops and biomass residues, and the effect of removal of the latter from soil have not been treated consistently. In contrast, the exclusion of upstream chain of biomass waste feedstocks is observed in practice. The bioethanol conversion process is mostly based on simultaneous saccharification and co-fermentation, characterized by high yield and low energy input. In this regard, the LCA results tend to under estimate the real impacts of the current technology. The choice of allocation methods strongly influences the final results, particularly when economic value is used as a reference. Substitution of avoided burden seems to be the most popular allocation method in practice, followed by partition based on mass, energy, and economic values. [Copyright &y& Elsevier]

Abstract: China, like many other countries, is promoting the development of liquid biofuel, including bioethanol and biodiesel. The Chinese government has set biofuel development targets for the coming decade and sanctioned a series of supportive policies. This paper provides a comprehensive overview of current liquid biofuel development in China, related government policies, and the potential opportunities and challenges for its future expansion. Our assessment is based on two rounds of in-depth fieldwork and a thorough literature review. The assessment shows that the prevailing concern on food security has pushed China to move from cereal-based to non-cereal-based biofuel production. Emphasis has also been put on utilizing new marginal land for feedstock production. Our assessment indicates that the targets of China''s biofuel development are cautious and feasible, but on the other hand there are still severe challenges for the sustainability of such development. A better understanding of China''s experience in striking a balance between energy security, food security and environmental protection would inform the debates across country boundaries and contribute to the efforts for global sustainability. [Copyright &y& Elsevier]

Abstract: This paper explores the potential for ethanol production and fuel substitution in Nepal based on established sugarcane production, installed capacity for sugar and ethanol production, economic opportunities for the national economy, and potential to reduce greenhouse gas emissions. At present conditions, 18,045m3 ethanol can be annually produced in Nepal without compromising the production of food products from sugar cane such as sugar, chaku and shakhar. The effects for the country can be manifold. As much as 14% of gasoline import reduction, and annual savings of US$ 10 million could be achieved through the introduction of the E20. The activity can provide an incentive for improved yields in sugarcane production, and help develop the industrial sector. This, in turn, will have a positive effect in terms of job and income generation in the rural areas where 85% of the population live. Improvement of agricultural practices for sugarcane could also have an indirect and positive effect on improving other agriculture activities. Furthermore, the use of ethanol in the transport sector will have a positive environmental effect while reducing CO2 emissions and combating pollution in the Kathmandu Valley. Finally, the substitution of ethanol in transport will imply lower imports of oil products and less draining of resources from the Nepalese economy. [Copyright &y& Elsevier]

Abstract: The introduction of biomass driven energy products like bioethanol, biodiesel, Combined Heat and Power production or solid biofuels is vital for achieving the targets set from the EU for the year 2010 (20% electricity production from RES). However, in order to reach these targets, a policy plan has to be formed concerning the conversion of biomass. The aim of this paper is to examine the logistics involved in the exploitation of already available or new biomass resources and to analyse various scenarios for the economic feasibility of the use of biomass and biofuels in Greece. [Copyright &y& Elsevier]