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Abstract: Biofuel is recognised as an important renewable and sustainable energy source to substitute fossil fuel. To date, biofuel has been evolved from first to fourth generation and they are mainly differed in feedstock and production technologies. Along with the evolution, various studies on different sustainability criteria have been conducted. In this review paper, the state of the art of technologies and assessment methods on economic performance, safety, health and environment (SHE) as well as social impact for biofuel production are reviewed. In addition, this review paper also evaluates the typical methodological framework used for systematic assessment during early process design phase. As conclusion, to establish the highest sustainability in biofuel production, continuous research and development on all sustainability-related aspects are very much needed. [Copyright &y& Elsevier]

Abstract: Global threats of fuel shortages in the near future and climate change due to green-house gas emissions are posing serious challenges and hence and it is imperative to explore means for sustainable ways of averting the consequences. The dual application of microalgae for phycoremediation and biomass production for sustainable biofuels production is a feasible option. The use of high rate algal ponds (HRAPs) for nutrient removal has been in existence for some decades though the technology has not been fully harnessed for wastewater treatment. Therefore this paper discusses current knowledge regarding wastewater treatment using HRAPs and microalgal biomass production techniques using wastewater streams. The biomass harvesting methods and lipid extraction protocols are discussed in detail. Finally the paper discusses biodiesel production via transesterification of the lipids and other biofuels such as biomethane and bioethanol which are described using the biorefinery approach. [Copyright &y& Elsevier]

Biomass is a valuable renewable source of energy as an alternative to fossil fuels. The main barriers in biomass and biofuel development are feedstock high cost, lack of reliable supply, and uncertainties. A systematic review of comprehensive solution tools to overcome the biomass supply chain (BSC) planning challenges is critical for both academic research and industry. Therefore, the aim of this study is to conduct a systematic review of BSC modeling and optimization and identify future research directions. We reviewed 300 papers that have been published in the past 40 years on this topic to assess the various models of BSCs, their objective functions, solution approaches, and decision levels employed. Results show that researchers are motivated to use mixed integer programming models for BSC problems because of the complexities of nonlinear models, as well as the simplicity of the linear approaches. There is a lack of multi-objective optimization approaches to address the economic, social, and environmental issues simultaneously in BSC. Although factors such as the political regulation, governmental subsidy, impact of biomass and oil price and cost of raw material are uncertain, most studies formally treat only the supply and demand of biomass as uncertain parameters. It is highly recommended that an integrated and holistic model that consider all facilities in the whole BSC be developed and tested with real data. In addition, incorporating strategic, tactical, and operational decision levels in the model is suggested to address the challenges of incorporating day-to-day inventory control and fleet management issues. • A review of 300 papers during 40-years related to the biomass supply chain. • Growing interests on the Non-linear Programming and Meta-heuristic methods. • Handling uncertainity in biomass supply chain is a challenge. • Multi-objective models considering sustainability criteria needs attention. • Lack of strategic, tactical and operational decisions in the optimization model. [ABSTRACT FROM AUTHOR]

Recently, extensive resources were dedicated to studying how to use catalysis to convert biomass into environmentally friendly fuels. Problems with this technology include the processing of lignocellulosic sources and the development/optimization of novel porous materials as efficient monofunctional and bifunctional catalysts for biomass fuel production. This paper reviews recent advancements in catalysts procedures. Besides, it offers assessments of the methods used in catalytic biomass pyrolysis. Understanding the catalytic conversion process of lignocellulosic biomass into bio-oil remains a key research challenge in biomass catalytic pyrolysis. [Display omitted] • Spotlighting of the role of catalysis for biomass conversion to green fuels. • Moving towards a cleaner environment using biofuels was reviewed. • Biomass plays a key role for creating a cleaner environment. • Challenges and future prospects were discussed in detail. [ABSTRACT FROM AUTHOR]

Microalgae have caught the world's attention for its potential to solve one of the world's most pressing issues—sustainable green energy. Compared to biofuels supplied by oil palm, rapeseed, soybean and sugar cane, microalgae alone can be manipulated to generate larger amounts of biodiesel, bioethanol, biohydrogen and biomass in a shorter time. Apart from higher productivity, microalgae can also grow using brackish water on non-arable land, greatly reducing the competition with food and cash crops. Hence, numerous efforts have been put into the commercialisation of microalgae-derived biofuel by both the government and private bodies. This paper serves to review conventional and novel methods for microalgae culture and biomass harvest, as well as recent developments in techniques for microalgal biofuel production. [ABSTRACT FROM AUTHOR]

The use of liquid fossil fuel as an energy source has long been considered unsustainable and most importantly the liquid fossil fuel will be diminished by the middle of this century. In addition, the fossil fuel is directly related to environmental degradation and greenhouse emission. Biofuel produced from plants, animals or algae products can offer an alternative to reduce our dependency on fossil fuel and assist to maintain healthy global environment. Micro-algae is becoming popular candidate for biofuel production due to their high lipid contents, ease of cultivation and rapid growth rate. This paper reviews the current state-of-the-art of biofuel from algae as a renewable energy source. [ABSTRACT FROM AUTHOR]

Abstract: Alongside with biofuel development, social acceptance issues have been underestimated. While social acceptance can emerge as powerful barrier for biofuel development, this article provides discussion on social acceptance in biofuel context. An acceptance framework based on life cycle biofuel production had been referred for a better understanding on social acceptance issues. Malaysia has been referred for the discussion as the country has faced with acceptance issue in their biofuel program. The discussion point out different societal groups will demand specific consideration for either support or oppose biofuel. This paper concludes that biofuel development will be constraint if social acceptance issues remain neglect. [Copyright &y& Elsevier]

Abstract: Field Pennycress (Thlaspi arvense L.) is a member of the mustard family and may be grown as a winter crop between traditional summer crops to produce renewable biomass for renewable diesel and jet fuel. This paper estimated total annual biofuel production potential of 15 million cubic metres from rotation between corn and soybeans on 16.2 million hectares in the Midwest without impact on food production. This study also investigated the life cycle greenhouse gas (GHG) emissions and energy balance of pennycress-derived Hydroprocessed Renewable Jet (HRJ) fuel and Renewable Diesel (RD). Both system expansion and allocation approaches were applied to distribute environmental impacts among products and co-products along the life cycle of each biofuel. The life cycle GHG emissions (excluding land use change) for RD and HRJ range from 13 to 41 g MJ−1 (CO2 eq.) and −18 to 45 g MJ−1 (CO2 eq.), respectively, depending on how the co-products are credited. The majority of the energy required for each biofuel product is derived from renewable biomass as opposed to non renewable fossil. The fossil energy consumptions are considerably lower than the petroleum fuels. Scenario analyses were also conducted to determine response to model assumptions, including nitrogen fertilizer application rate, nitrogen content in crop residues, and sources of H2. The results show that pennycress derived biofuels could qualify as advanced biofuels and as biomass-based diesel as defined by the Renewable Fuels Standard (RFS2). [Copyright &y& Elsevier]

Abstract: The massive need for sustainable energy has led to an increased interest in new energy resources, such as production of algae, for use as biofuel. There are advantages to using algae, for example, land use is much less than in terrestrial biofuel production, and several algae species can double their mass in 1day under optimized conditions. Most algae are phototrophs and some are nitrogen-fixing. Algae production therefore requires only small amounts of amendments such as carbon sources and nutrients. In the present paper an experiment was performed using water sampled from Lake Mälaren in Sweden. The lake water is considered nutrient rich, has relatively neutral pH and is rich in organic compounds and suspended solids. The idea behind this research was to enhance indigenous algae production rather than inoculate new species into the system. A simple experimental setup was designed where algae biomass growth was measured regularly over a 13day period. FT-IR absorption spectra were evaluated in order to determine protein, lipid, carbohydrate and silicate contents of the algae. The algae community structure was characterized throughout the production cycle. Furthermore, the potential for energy supply for the transportation sector in the Mälardalen region from algae cultivated as tested in the experiment was evaluated. [Copyright &y& Elsevier]

Abstract: Biofuels are promoted in many parts of the world. However, concern of environmental and social problems have grown due to increased production of biofuels. Therefore, many initiatives for sustainability criteria have been announced. As a part of the European Union (EU) renewable energy promotion directive (RED), the EU has introduced greenhouse gas (GHG) emission-saving requirements for biofuels along with the first-ever mandate methodology to calculate the GHG emission reduction. As explored in this paper, the RED methodology, based on life-cycle assessment (LCA) approach, excludes many critical issues. These include indirect impacts due to competition for land, biomass and other auxiliary inputs. Also, timing issues, allocation problems, and uncertainty of individual parameters are not yet considered adequately. Moreover, the default values provided in the RED for the GHG balances of biofuels may significantly underestimate their actual impacts. We conclude that the RED methodology cannot ensure the intended GHG emission reductions of biofuels. Instead, a more comprehensive approach is required along with additional data and indicators. Even if it may be very difficult to verify the GHG emission reductions of biofuels in practice, it is necessary to consider the uncertainties more closely, in order to mitigate climate change effectively. [Copyright &y& Elsevier]

Abstract: The deployment of biofuels is significantly affected by policy in energy and agriculture. In the energy arena, concerns regarding the sustainability of biofuel systems and their impact on food prices led to a set of sustainability criteria in EU Directive 2009/28/EC on Renewable Energy. In addition, the 10% biofuels target by 2020 was replaced with a 10% renewable energy in transport target. This allows the share of renewable electricity used by electric vehicles to contribute to the mix in achieving the 2020 target. Furthermore, only biofuel systems that effect a 60% reduction in greenhouse gas emissions by 2020 compared with the fuel they replace are allowed to contribute to meeting the target. In the agricultural arena, cross-compliance (which is part of EU Common Agricultural Policy) dictates the allowable ratio of grassland to total agricultural land, and has a significant impact on which biofuels may be supported. This paper outlines the impact of these policy areas and their implications for the production and use of biofuels in terms of the 2020 target for 10% renewable transport energy, focusing on Ireland. The policies effectively impose constraints on many conventional energy crop biofuels and reinforce the merits of using biomethane, a gaseous biofuel. The analysis shows that Ireland can potentially satisfy 15% of renewable energy in transport by 2020 (allowing for double credit for biofuels from residues and ligno-cellulosic materials, as per Directive 2009/28/EC) through the use of indigenous biofuels: grass biomethane, waste and residue derived biofuels, electric vehicles and rapeseed biodiesel. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes a general modeling approach for optimal planning of energy systems subject to carbon and land footprint constraints. The methodology makes use of the source–sink framework derived from the analogies with resource conservation networks used in process integration. Two variants of the modeling approach are developed for some of the important technologies for carbon emissions abatement: liquid biofuels in transportation, and carbon dioxide capture and storage in power generation. Despite the positive impact on environment, widespread use of these technologies has certain disadvantages. In case of biofuels, their production may strain agricultural resources, that are needed also for satisfying food demands. At the same time, carbon capture and storage is rather expensive technology and its practical implementation in power facilities must be carefully considered and planned. Optimum utilization of both technologies is identified with flexible and expandable mathematical modeling framework. Case studies are used to illustrate the variants of the methodology. [Copyright &y& Elsevier]

Abstract: When discussing how society can decrease greenhouse gas emissions, the transport sector is often seen as posing one of the most difficult problems. In addition, the transport sector faces problems related to security of supply. The aim of this paper is to present possible strategies for a road transport system based on renewable energy sources and to illustrate how such a system could be designed to avoid dependency on imports, using Sweden as an example. The demand-side strategies considered include measures for decreasing the demand for transport, as well as various technical and non-technical means of improving vehicle fuel economy. On the supply side, biofuels and synthetic fuels produced from renewable electricity are discussed. Calculations are performed to ascertain the possible impact of these measures on the future Swedish road transport sector. The results underline the importance of powerful demand-side measures and show that although biofuels can certainly contribute significantly to an import-independent road transport sector, they are far from enough even in a biomass-rich country like Sweden. Instead, according to this study, fuels based on renewable electricity will have to cover more than half of the road transport sector’s energy demand. [Copyright &y& Elsevier]

Abstract: The aim of the present paper is to investigate the feasibility of bio-ethanol production by batch fermentation of ricotta cheese whey (“Scotta”), a dairy industry waste characterized by lactose concentration ranging from 4.5% to 5.0% (w/w) and, with respect to traditional (raw) whey, by much lower protein content. Scotta, therefore, could represent an effective non-vegetable source for renewable energy production. The microrganism used to carry out the fermentation processes was the yeast Kluyveromyces marxianus. Preliminary experiments, performed in aerobic conditions on different volumes of scotta, have shown the actual growth of the yeast. The subsequent fermentation experiments were carried out, in anaerobic conditions, on three different substrates: scotta, raw cheese whey and deproteinized whey. The experimental data have demonstrated the process feasibility: scotta is an excellent substrate for fermentation and exhibits better performance with respect to both raw cheese whey and deproteinized whey. Complete lactose consumption, indeed, was observed in the shortest time (13h) and with the highest ethanol yield (97% of the theoretical value). [Copyright &y& Elsevier]