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Due to their potential role in addressing the challenges of energy and environment, biofuels have been receiving significant attention from scientists in various disciplines and countries. Over the past few decades, the biofuel science has undergone major changes with regard to its rate of development, focus, and the contributing countries. We put the evolution the biofuel science into context by analyzing 49,000 relevant papers (comprising 0.26% of all publications across physical and life sciences) published between 1990 and 2014. We first determine the scientific contributions of different countries to the science on biofuels, and then analyze how the R&D expenditure and biomass availability is associated with their outputs. Subsequently, the structure of biofuel science in terms of the links between biomass feedstocks and final products are quantitatively discussed. We find that 28%, 16%, and 15% of all papers considered are published by researchers from the EU, China, and USA, respectively. Denmark, Sweden, and Finland have the highest number of biofuel-related publications per capita (i.e. 133, 113, and 103 papers per million capita and annum, respectively). The percentage share of studies on edible, lignocellulosic, and algal biomass are 46%, 40%, and 14%, respectively. Fermentation, hydrolysis, and esterification are the most widely studied conversion pathways, while liquefaction and life cycle assessment are the most cited subfields. Finally, using United States’ statistics, it is shown that upon accounting for the time delay between the nominal budget release year and the calendar year in which corresponding papers would ultimately appear in print, the publication trend was closely correlated to the R&D expenditure (r=0.98). [ABSTRACT FROM AUTHOR]

Abstract The Canadian province of Quebec has set for 2030 a greenhouse gas (GHG) emission reduction target of 37.5% below 1990 levels. Meeting such a reduction target requires in particular a rapid transition to a low-carbon energy system. This paper proposes prospective energy scenarios for Quebec up to 2030, under different GHG emission reduction constraints (up to a 40% reduction). The main objective is to explore the role of bioenergy in achieving the reduction targets. Our analysis is based on the North American TIMES Energy Model (NATEM). It belongs to the MARKAL/TIMES family of models supported by the International Energy Agency, and includes a detailed bioenergy sector. Compared to the reference case (baseline), our results indicate a larger share of bioenergy in 2030 (up to a threefold increase in the most stringent GHG reduction scenario), with up to a fourfold increase in the total amount of feedstock used for bioenergy production. Our study envisions thus a much larger penetration of bioenergy than the one proposed by the government of Quebec in its 2030 Energy Policy. Highlights • Prospective energy scenarios for the Province of Quebec under GHG reduction targets. • Use of a TIMES optimization energy model to derive socially optimal solutions. • Explore the role of bioenergy in achieving the reduction targets. • Results indicate a larger penetration of bioenergy than the one proposed by the government of Quebec in its 2030 Energy Policy. [ABSTRACT FROM AUTHOR]

Agricultural solid biomass has been widely recognized as an important source of renewable energy with huge production potential. The utilisation of agricultural solid biomass as feedstock for energy production is continuously growing all over Europe. As shown in the current country's balance of energy production and consumption, Croatia is highly dependent on imported fossil fuels. The aim of this paper is to determine the available agricultural solid biomass and its energy potential in Croatia. The quantity and energy potential of solid biomass refer to post-harvest residues, pruning residues, agro-industrial solid waste and biomass from Miscanthus energy crop. In relation to potentially available agricultural biomass, three scenarios have been developed (progressive – S1, optimistic - S2, and conservative – S3) of introducing solid biomass in the renewable energy production sector. On the basis of these scenarios, it can be concluded that in Croatia the following quantities of agricultural biomass are available: 3050.3 t (S1); 1441.8 t (S2); and 733.68 t (S3). These quantities give energy potential of 51.14 PJ (S1), 24.06 PJ (S2), and 12.18 PJ (S3) respectively. [ABSTRACT FROM AUTHOR]

Hydrogen can be produced through different methods. Various biomass can be used as low-cost substrate for fermentative hydrogen production, which significantly reduces the hydrogen production cost. Furthermore, biohydrogen production from biomass wastes can achieve dual benefits of clean energy generation and waste management since agricultural and municipal wastes can be disposed at the same time. However, the application of hydrogen production from biomass meets the bottlenecks of low hydrogen production rate and substrate degradation rate. In this paper, various biomass as feedstock, including waste activated sludge produced form wastewater treatment plant, algae, agricultural residuals and municipal wastes used for biological hydrogen production, was reviewed. Since the hydrolysis to smaller molecules is the rate-limiting step for biomass degradation, a pretreatment step can enhance both the hydrogen production efficiency and biomass degradation rate. Pretreatment process can destroy the crystal structure of macromolecular substances and reduce their polymerization degree. Therefore the trapped components can be released through cell wall lysis and delignification of lignocellulosic biomass to make higher proportion of readily fermentable substances accessible for microorganisms. Various pretreatment methods used for treating biomass as feedstock for hydrogen production were analyzed and compared. Physical treatment, chemical treatment, biological treatment and a combination of different treatments are usually used for the pretreatment of biomass. Physical treatment methods include mill, grind, ultra-sonication, heat, freeze and thaw, microwave and ionizing radiation; chemical treatment methods comprise acid and alkaline treatment, oxidation by oxidizing agent and addition of methanogenic inhibitors; biological treatment methods mainly consist of enzymatic treatment and bacterial hydrolysis. Pretreatment is a critical process for fermentative hydrogen production from biomass. Considerable efforts are needed from both technical and managing aspects to achieve a full-scale application of fermentative hydrogen production from biomass. [ABSTRACT FROM AUTHOR]

This paper analyzes the performance and emissions of biodiesel from different feedstocks. The main goal of this paper is to provide information to the engineers, industrialists and researchers who are interested on biodiesel and to emphasise biodiesel as a promising alternative replacement for fossil fuels. A substantial number of literatures from highly rated journals in scientific indexes were cited preferentially since 2000. The performance and emissions indicators such as brake torque, brake power, BTE, EGT, BSFC NO x , PM, CO, CO 2 , HC and smoke density have been evaluated in comparison to pure diesel. The results showed that different sources of biodiesel feedstocks give different results to engine performance and emissions. Surprisingly some of the research yielded favourable results towards the biodiesel as compared to pure diesel. The study concluded that biodiesel can be used in compression ignition engine as a replacement of diesel fuel to fulfil the global energy demand. However, further research on about optimisation, cost-effectiveness and availability of biodiesel needs to be carried out to help ensure that biofuel will be able to fully replace fossil fuel. [ABSTRACT FROM AUTHOR]

This paper summarizes the biodiesel production capacities and the indigenous oil-based feedstock potential of Serbia for the first time. The current demands and future trends in diesel fuel consumption in Serbia are presented in order to estimate the biodiesel perspectives. The comprehensive review explores the potentials of the available conventional biodiesel sources (oilseed crops), as well as the next generation biodiesel sources, including waste cooking oil and oil from non-edible agro-food wastes that were previously reported as potential biodiesel feedstock in Europe. Results suggest that the Serbian agriculture can provide oilseed crops for the production of 128,000–266,000 t of biodiesel annually in addition to the quantities of oilseed crops required by the domestic food and fodder industries. Nevertheless, selecting edible vegetable oils as a potential feedstock for biodiesel cannot be considered as a long-term choice due to the associated “food versus fuel” debate. Thus, exploring the non-edible waste feedstock is important. Around 10,000 t of biodiesel could be produced from the collectable waste cooking oil. Other potential alternative oil resources indigenous for Serbia, such as tomato, grape and tobacco seeds, can provide raw material for the production of further ca. 8,000 t of biodiesel annually. Lack of governmental incentives and higher profitability of the edible oil sector have caused that the installed capacities for biodiesel production (ca. 126,000 t annually) are largely out of operation since 2008. Nevertheless, the results suggest that with the introduction of appropriate measures there is a realistic basis to fulfil the goals set by the National Renewable Energy Action Plan which requires that the annual biodiesel production from domestic sources should reach 98,000 t by 2020 in Serbia. [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]

Combined bioheat and biopower (CBHBP) is named to emphasize that a biomass source is used as the feedstock for the production of combined heat and power (CHP). Turkey is a country with rich biomass potential; however, traditional utilization is predominant. The purpose of this paper is to describe the entire value chain of biomass-to-biopower by focusing on the current commercial technologies in the world and to provide an alternative solution for modern utilization of solid biomass sources in Turkey, while being a reference for other countries interested in biopower. The first aim is to explore the major conversion technologies for CBHBP production considering the entire value chain of biomass-to-biopower, with a focus on the most established path applied to solid biomass sources worldwide. The next aim is to examine the status of biomass energy in Turkey, concentrating on current biopower applications. This review shows that combustion coupled with steam turbine technology is the primary approach to produce biopower and/or bioheat from solid biomass sources worldwide. In different countries, CBHBP production through distributed generation (DG) is seen as a viable way of taking advantage of local biomass sources. In Turkey, biopower production through thermochemical conversion technologies that require solid biomass sources is still at an early stage. A challenging increase in biopower development is needed. In conclusion, modern utilization of solid biomass sources through distributed CBHBP production based on combustion and steam turbine technology, in line with worldwide biopower developments, is a solution to utilize the existing potential efficiently that can be implemented in the short term. Distributed CBHBP should be implemented as soon as possible and become widespread in the country, especially in rural areas near forest villages and in agricultural regions where solid biomass sources are locally available and where there is a constant heat/cold and power demand. [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]

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]

The production of biofuels from lignocellulosic feedstock is attracting considerable attention in the United States and globally as a strategy to diversify energy resources, spur regional economic development and reduce greenhouse gas emissions. Because of the wide variation in feedstock types, compositions and content of convertible organics, there is a growing need to better understand correlations among feedstock quality attributes and conversion performance. Knowledge of the feedstock impact on conversion is essential to supply quality controlled, uniform and on-spec feedstocks to biorefineries. This review paper informs the development of meaningful feedstock quality specifications for different conversion processes. Discussions are focused on how compositional properties of feedstocks affect various unit operations in biochemical conversion processes, fast pyrolysis and hydrothermal liquefaction. In addition, future perspectives are discussed that focus on the challenges and prospects of addressing compositionally intrinsic inhibitors through feedstock preprocessing at regionally distributed depots. Such preprocessing depots may allow for the commoditization of lignocellulosic feedstock and realization of stable, cost-effective and quality controlled biomass supply systems. [ABSTRACT FROM AUTHOR]

Solid biomass and waste are major sources of energy. They account for about 80% of total primary energy consumed in Nigeria. This paper assesses the biomass resources (agricultural, forest, urban, and other wastes) available in Nigeria and the potential for biofuel production from first, second, third and fourth generation biomass feedstocks. It reviews the scope of biomass conversion technologies tested within the country and the reports on the technology readiness level of each. Currently, most of the emerging biofuels projects in Nigeria utilize first generation biomass feedstock for biofuel production and are typically located many miles away from the petroleum refineries infrastructures. These feedstocks are predominantly food crops and thus in competition with food production. With significant availability of non-food biomass resources, particularly in the Niger Delta region of Nigeria, and the petroleum refineries located in the same area, it is pertinent to consider expanding use of the petroleum refinery׳s infrastructure to co-process non-food biomass into bio-intermediate oil for blending with petroleum. This not only addresses the potential food versus fuel conflict challenging biofuel production in Nigeria, but also reduces the cost of setting up new bio-refineries thus eliminating the transportation of ethanol to existing petroleum refineries for blending. In view of this, it is recommended that further research be carried out to assess the feasibility of upgrading existing refineries in Nigeria to co-process bio-based fuels and petroleum products thus achieving the targets set by the Nigeria Energy Commission for biofuel production in the country. [ABSTRACT FROM AUTHOR]

Abstract: As the world confronts a reported food shortage and rising fuel prices, scientists around the globe are scrambling to develop biofuel feedstocks that would not divert food crops to energy. It is apparent that the demand for biodiesel is expected to increase in near future and although many edible oils might be the cheapest feedstock for biofuel production. But it may not be sustainable source to meet this increasing demand. This justifies the need to use non-edible oil seeds that can be the reliable sustainable feedstock for biofuel production. Furthermore, most of the non-edible seeds bearing trees have the potentials of reclaiming wasteland and does not compete with food crop for limited growing regions. It thus becomes imperative to search for dedicated non-edible feedstocks and their suitability for biodiesel production. This paper attempts to make an assessment of current energy scenario, potential of non-edible oil over edible oils, selected non-edible oil seeds as biodiesel feedstocks, impact of biofuel on environment and future direction. Experimental analysis by different researchers on these non-edible oils showed their great potential as feedstocks for biodiesel production. This paper also reviews the biology, distribution and chemistry of selected non-edible oil seeds plants. [Copyright &y& Elsevier]

Vegetable oils and animal fats represent promising alternatives to diesel engine fuel because they can be obtained from different feedstocks and renewable sources; also their properties are close to diesel fuel. The direct use of these biofuels as a diesel engine fuel can cause several problems in engine performance and emissions. In order to obtain a more engine-friendly fuel, it is necessary to change the biofuels’ properties for which different methods have been used. One of the possibilities is using emulsification techniques in order to obtain emulsified biofuels (emulsions or microemulsions); through this method it is possible to lower viscosity and improve the atomization. However, emulsification techniques applied to vegetable oils and animal fats have not been studied thoroughly. For this reason, this paper presents an overview on the formulation and characterization of the emulsified biofuels using vegetable oils and animal fats, as well as the main experimental results reported about its use as a diesel engine fuel in the scientific literature. [ABSTRACT FROM AUTHOR]

Air transport describes an inevitable part in the day to day life of the modern world. It is highly responsible for the worldwide social contacts and business developments. The use of petroleum fuels as energy source for air transport is not sustainable. Aviation is one of the leading contributors to the total greenhouse gas emissions. Also, the fossil fuel prices are becoming more volatile day by day. So it is very essential to introduce and industrialize alternative aviation fuels generated from renewable resources, especially biomass. A number of industrial commitments and collaborations have emerged to find alternative ways to reach bio aviation fuels. Research on the conversion of biomass based sources to bio jet fuels is of current interest. The main concern is the production of biojet fuel, from renewable resources, with relatively low greenhouse gas life cycle and sustainability with affordable price. The present paper overviews the opportunities and challenges in the development of alternative fuels for aviation. The production process, feedstock used and the most promising global projects are also reviewed. [ABSTRACT FROM AUTHOR]

Sustainability is a fundamental topic to be addressed in the establishment of a market for jet biofuels in Brazil. The objective of this paper is to enhance the discussion on sustainability of biofuels, and to discuss the main gaps to meet the requirements of sustainability for four groups of feedstock: sugars and starch, oil, lignocelluloses, and wastes. Some general common conclusions can be made for all the analyzed feedstock. In the social sphere, the main positive impacts are the high potential for job creation, income generation and regional development. Regarding the gaps for compliance with sustainability requirements, the following aspects were common to all groups of feedstock: great number of laws and rules; different interpretations and lack of knowledge on how to apply some laws; certain labor laws not adapted to the rural context. The main potential positive impact generated by compliance with requirements is greenhouse gas (GHG) emissions reductions compared to fossil fuels. [ABSTRACT FROM AUTHOR]

Abstract: Meeting future policy targets for bioenergy development worldwide poses major challenges for biomass feedstock supply chains in terms of competitiveness, reliability and sustainability. This paper reviews current knowledge on the sustainability of agricultural feedstock supply chains and emphasizes future research needs. It covers annual and perennial feedstocks, and environmental, economic and social aspects. Knowledge gaps and technological options to assess and meet sustainability criteria are reviewed from plot to landscape and global scales. Bioenergy feedstocks present a wide range of dry matter yields, agricultural input requirements and environmental impacts, depending on crop type, management practices, and soil and climate conditions. Their integration into farmers׳ cropping systems poses specific challenges in terms of environmental impacts, but also opportunities for improvements via the use of grass–legume intercropping or residues from biomass conversion processes. Taking into account the spatial distribution of bioenergy crops is paramount to assessing their environmental impacts, in particular, on biodiversity or the food versus energy competition issue. However, few modeling frameworks convey the full complexity of the underlying processes and drivers, whether economic, social or biophysical. In particular, social impacts of bioenergy projects are seldom assessed and there is no methodological consensus. The main research areas identified involve multi-crop and multi-site experiments, along with modeling, to optimize management practices and cropping systems producing bioenergy, possibly on alternative lands and under future climate changes; the design of innovative cropping systems using expert knowledge to ensure suitable integration into farmers׳ cropping systems; the collection of detailed data on the location of bioenergy crops to validate theoretical modeling frameworks and improve sustainability assessment; tackling direct and indirect effects of bioenergy development on land-use changes via coupled economic and agronomical models; investigating the effect of perennial stands on biodiversity in relation to previous land-use and landscape structure; and further developing currently-available methodologies to fully appraise the social implications of bioenergy projects. [Copyright &y& Elsevier]

Abstract: The paper assesses greenhouse gas (GHG) emissions of forest bioenergy supply and utilization in Finland. Each step in the supply chains of harvesting residues (HR), small-diameter energy wood (EW) and stumps (ST) is assessed separately, with geography-related differences between Northern and Southern Finland (NF and SF) taken into consideration. Furthermore, the GHG performance of five distinct bioenergy options—(1) combined heat and power production, (2) condensing power production, (3) torrefied pellets, (4) gasification, and (5) pyrolysis oil production—is assessed and compared with that of current reference systems in Finland and also the European Union (EU) sustainability criteria. If soil carbon stock (SCS) changes and possible storage emissions are omitted, the GHG emissions deriving from the supply chain of comminuted forest biomass to plants are 2.4, 3.0, and 2.6gCO2eqMJ−1 for HR, EW, and ST in SF, respectively. In NF, the corresponding values are 2.9, 3.6, and 3.2gCO2eqMJ−1, respectively. If SCS changes and possible emissions from storage are accounted for, the emissions for HR, EW, and ST are in the ranges 9.2–49.2, 24.4–64.4, and 33.1–73.1gCO2eqMJ−1 in SF and 12.7–52.7, 29.4–69.4, and 39.5–79.5gCO2eqMJ−1 in NF. Most supply-chain GHG emissions arise from SCS changes and possible emissions from storage of comminuted biomass, both of which may involve significant uncertainty factors. In comparison to local reference systems, significant GHG savings can be achieved through energy utilization of forest biomass, but if SCS changes and, in particular, storage emissions are taken into account, fulfillment of the EU sustainability criteria is not guaranteed. [Copyright &y& Elsevier]

Abstract: More than a century long research and development on utilization of lignocellulosic biomass for biofuels and biomaterials are still in its formative years and the main reason for this is the over-dependence on the fossil fuel reserves. Active research works in the last decades has resulted in a few industrial units to start, stumble and become the forerunners of future biorefineries. But the current system of feedstock logistics and biomass valorization has many drawbacks that make the biorefinery operations unsuccessful throughout the world. This paper discusses the important lignocellulosic feedstocks used, existing and alternate logistical practices, and the pretreatment of biomass for the biorefinery operations. It also emphasises on the importance of decentralized pretreatment of lignocellulosic biomass for the centralized biorefinery operations. [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: This paper primarily presents an overall review of the use of microalgae as a biofuel feedstock. Among the microalgae that have potential as biofuel feedstock, Chlorella, specifically, was thoroughly discussed because of its ability to adapt both to heterotrophic and phototrophic culture conditions. The lipid content and biomass productivity of microalgae can be up to 80% and 7.3g/l/d based on the dried weight of biomass, respectively, making microalgae an ideal candidate as a biofuel feedstock. The set-up of the system and the biomass productivity of microalgae cultivated in an open pond and a photobioreactor were also compared in this work. The effect of the culture condition is discussed based on the two-stage culture period. The issues that were discussed include the light condition and the CO2, DO and N supply. The microalgal productivities under heterotrophic and phototrophic culture conditions were also compared and highlighted in this work. The harvesting process and type of flocculants used to aid the harvesting were highlighted by considering the final yield of biomass. A new idea regarding how to harvest microalgae based on positive and negative charges was also proposed in this work. The extraction methods and solvents discussed were primarily for the conventional and newly invented techniques. Conversion processes such as transesterification and thermochemical processes were discussed, sketched in figures and summarized in tables. The cost–benefit analysis of heterotrophic culture and the cultivation system was highlighted at the end of this work. Other benefits of microalgae are also mentioned in this work to give further support for the use of microalgae as a feedstock for biofuel production. [Copyright &y& Elsevier]

Abstract: This paper presents and analyses international solid biofuel trade and concludes upon interactions with bioenergy policies and market factors. It shows that trade has grown from about 56 to 300PJ between 2000 and 2010. Wood pellets grew strongest, i.e. from 8.5 to 120PJ. Other relevant streams by 2010 included wood waste (77PJ), fuelwood (76PJ), wood chips (17PJ), residues (9PJ), and roundwood (2.4PJ). Intra-EU trade covered two thirds of global trade by 2010. Underlying markets are highly heterogeneous; generally though trade evolved whenever supply side market factors coincided with existing/emerging demand patterns. Market factors and policies both defined trade volumes; though policy changes did not have as prominent effects on trade developments as in the liquid biofuel sector. Economic viability is the key limiting factor. Main exporting countries have low feedstock costs and already existing wood processing industries. Trade-relevant aspects are the commodity''s monetary value; determined by its homogeneity, heating value, and bulk density. Consumer markets are diverse: in residential heating, demand/trade patterns have been influenced by local biofuel availability and short-term price signals, i.e. mainly price competitiveness and investment support for boilers/stoves. Commodities are mainly sourced regionally, but price differences have triggered a growing trade. The industrial segment is greatly influenced by policy frameworks but more mature (e.g. established routes). Trade is strictly linked to margins (defined mainly by policies) and combustion technologies. Uncertainties in the analysis are due to data gaps across and within databases regarding import/export declarations. To estimate bioenergy related trade, anecdotal data was indispensable. We believe datasets should be streamlined across international institutions to eventually enable reporting of global trade beyond digit-6-level. Research is needed to provide further insights into informal markets. Interrelations between trade factors are particularly relevant when mapping future trade streams under different policy/trade regime scenarios. [Copyright &y& Elsevier]

Abstract: The current status of and challenges associated with bioenergy production and utilization in Korea are reviewed in this paper. Bioenergy (particularly transport biofuels) has emerged as a promising option for mitigating Korea''s CO2 emissions and enhancing its energy security. Korea''s limited biomass resources and the high cost of biofuels are the major barriers to achieving 2030''s implementation targets. Efforts to identify new suitable biomass resources for biofuels production are ongoing and intensive. Aquatic biomasses including algae and plantation wastes collected in the Southeast Asia region have been found to have great potential as feedstocks. R&D on technologies that can more efficiently convert biomass materials to biofuels also are underway. It is expected that cost-effective biofuels will be in adequate supply from 2020 and that, by 2030, their use will contribute effectively to the realization of sustainable growth in Korea. [Copyright &y& Elsevier]

Abstract: Today, sustainability is the buzzword in the developmental parlance. This has brought the issue of availability and utilization of energy into sharp focus. There is an urgent need to find viable alternative to fossils, mainly petroleum. It not only provides the major share of our present energy needs but also feeds the organic chemicals industry with vital raw materials. Among many alternative energy sources being explored biomass is the only one that has the potential for such dual application. Comprehensive yet judicious exploitation of biomass is, therefore crucial. The emerging concept of biorefineries is important in this context which advocates multiprocess and multiproduct biomass based industries. But everything green need not always be clean and sustainable as populism often makes it to be. Needless to say, the choices of feedstocks, processes as well as product mix are many. There is a need to critically examine them. This paper presents a status review of biorefineries from the stand point of feedstocks, products and processes. [Copyright &y& Elsevier]

Abstract: Biomass is the major energy source in Ghana contributing about 64% of Ghana''s primary energy supply. In this paper, an assessment of biomass resources and biofuels production potential in Ghana is given. The broad areas of energy crops, agricultural crop residues, forest products residues, urban wastes and animal wastes are included. Animal wastes are limited to those produced by domesticated livestock. Agricultural residues included those generated from sugarcane, maize, rice, cocoa, oil palm, coconut, sorghum and millet processing. The urban category is subdivided into municipal solid waste, food waste, sewage sludge or bio-solids and waste grease. The availability of these types of biomass, together with a brief description of possible biomass conversion routes, sustainability measures, and current research and development activities in Ghana is given. It is concluded that a large availability of biomass in Ghana gives a great potential for biofuels production from these biomass resources. [Copyright &y& Elsevier]

Abstract: This paper presents the status of research of biomass potential for producing electrical energy in Albania. Biomass potential can be generated by different sources. Three types of biomass energy sources are included: dedicated bioenergy crops, agricultural and forestry residues and waste. The technical electrical energy considered in this study was calculated with two converting techniques: (1) combustion of the feedstock directly in an incinerator and then driving a steam generator for producing electrical energy and (2) production of biogas from an anaerobic digester and running a turbine for electrical energy generation. Analysis of the potential biomass resource quantity was computed according to statistical reports, literature review and personal investigations. From the biomass residue potential was calculated in terms of the theoretical energy content (total heating value) of every type of feedstock and the technical energy content for every Albanian prefecture according to different burning processes and different operation efficiencies. Results show that Albania was producing around of 4.8 million tons of dry biomass in year 2005. The theoretical energy content of biomass in Albania was 11.6 million MWh/a, and the technical electrical energy production was 3 million MWh/a. The electrical energy produced is equivalent to 45.8% of total Albania Country annual electrical consumption. In Albania Country, residues from agriculture, forest and urban waste represent a large biomass potential. By actual conversion techniques it is possible to generate one third of the theoretical heat energy into technical electrical energy. The use of heat from cogeneration plants depends on local heat provision conditions. It is another big energy potential but excluded in this study, so the rest of energy is considered as heat losses. [Copyright &y& Elsevier]