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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: 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]