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News and Trends
http://www.globalbioenergy.org/fileadmin/user_upload/gbep/docs/2011_events/12th_TF_Sustainability_WashingtonDC_17-20_May_2011/GBEP_sustainability_indicators.pdf The Global Bioenergy Partnership (GBEP), a government-level organization of 23 countries recently announced that they have established a set of 24 bioenergy sustainability guidelines. The sustainable bioenergy indicators are described as "voluntary", "practical" and "science-based", with the objective of helping countries assess and develop sustainable production and use of bioenergy. According to the GBEP press release, "The 24 indicators identified by GBEP partners and observers take a holistic approach to assessing many important aspects of the intersection of bioenergy and sustainability, including greenhouse gas emissions, biological diversity, the price and supply of a national food basket, access to energy, economic development, and energy security". The indicators are grouped into three main categories: (1) the Environmental Pillar (which includes: life cycle GHG emissions, water use/efficiency, biological diversity in the landscape), (2) the Social Pillar (which includes price and supply of a national food basket, jobs in the bioenergy sector, income change), and (3) the Economic Pillar (which includes:productivity, net energy balance, gross value added, infrastructure/logistics for distribution of bioenergy, change in the consumption of fossil fuels and traditional use of biomass). The GBEP has also plans to launch a capacity building initiative for the promotion of the optimum use of bioenergy for sustainable development. http://www.springerlink.com/content/l774517j664v027r/ In order to evaluate whether a particular biofuel is sustainable, the major factors that are often considered are (1) the net energy yield (i.e. the difference in the energy derived from the burning of the biofuel for transport or other uses and the energy used to produce it), (2) the greenhouse gas (GHG) emissions impact in terms of net carbon dioxide released (analogous to the "carbon footprint"), (3) food security impacts, (4) biodiversity impacts, and (5) the water-use impacts. Life Cycle Analysis (LCA) is the often-used tool to assess biofuel sustainability, and this usually factors-in the previously mentioned considerations. Recently, an international team of scientists, headed by researchers from Energy Research Centre of The Netherlands, the VU Free University of Amsterdam, and the Netherlands Environmental Assessment Agency, report that large scale biofuel feedstock cultivations may also exert a major impact on the nitrogen cycle. In their paper which reviewed the state of knowledge on nitrogen and biofuels, they mention the possibility that large scale biomass cultivations for biofuel production could accelerate the nitrogen cycle, through (1) increased fertilizer use resulting in losses to the environment and (2) additional emissions of oxidized nitrogen (a gas with similar adverse impacts as other greenhouse gases). In their review paper, an overview of "nitrogen-relevant processes in relation to biomass for energy use was presented". They also attempted to quantify the major nitrogen issues based on literature values, and discussed whether current LCA activities address the major nitrogen issues. The full review paper is published in the journal, Nutrient Cycling in Agroecosystems (URL above). Energy Crops and Feedstocks for Biofuels Productionhttp://www.sciencedirect.com/science/article/pii/S0961953410002588 Researchers from the Department of Agroenvironmental Science and Technology, University of Bologna (Italy) recently reviewed "the potential of several rotations with energy crops and their possibilities of being included alongside traditional agriculture systems across different agro-climatic zones within the European Union". The review was made in anticipation of a rapid increase in the cultivation of energy crops for biofuel production over large areas of land in the next few years. As such, knowledge of rotational systems for these crops will be useful. Well planned crop rotations are said to provide some advantages over continuous monoculture systems. This includes better nutrient cycling efficiency, maintenance of long-term land productivity, and control of pests and diseases. However, the researchers found that information about rotations of "dedicated bioenergy crops" was sparse in the literature. Among the findings of the review were: (1) for food crops which can be also cultivated as energy crops (such as sunflower or rapeseed), the rotational management practices described in the available literature can serve as a general guide and could be applicable, (2) "rotational management of new energy crops such as biomass sorghum, flax, Ethiopian mustard, kenaf, hemp, among others, is not well developed and fragmentary; therefore it is urgent to systematize the available information to fill the existing knowledge gaps", (3) for the establishment of specialized bioenergy crop rotations, additional studies will be needed in order to identify/develop new and better oilseed crops that are both pest-resistant and can have high oil yields for biodiesel production. The full paper is published in the journal, Biomass and Bioenergy (URL above). Biofuels Processing(article in provisional pdf during time of access) http://www.biotechnologyforbiofuels.com/content/pdf/1754-6834-4-11.pdf Researchers from the Department of Chemical and Biochemical Engineering, Technical University of Denmark, investigated the interactive effects of pretreatment pH, temperature and reaction time on the subsequent monosaccharide yields (glucose, xylose) of mildly pretreated wheat straw. In the production of biofuel ethanol from lignocellulosic biomass, such as wheat straw, the material undergoes three processing stages: (1) pretreatment to remove the tight lignin wrapping in the biomass; pretreatment liberates/exposes the carbohydrate molecules within the biomass, (2) enzymatic treatment (also called "enzymatic saccharification") to break-down the carbohydrate molecules into component monosaccharides (mainly glucose and xlose), and (3) fermentation of the component monsaccharides to ethanol. Pretreatment has been identified as a crucial process among these three processes, because it determines how much of the carbohydrates are available for enzymatic saccharification and fermentation. Pretreatment methods include additions of acid, alkali and oxidizing agents, in combination with heat. The pH, temperature, and reaction time usually determine the performance of a particular pretreatment in terms of the subsequent monoscaccharide yields. The Danish researchers conducted statistical experimental designs in order to investigate the interplay of pH, temperature and time during wheat straw pretreatment. They found that at temperatures below 140 degrees Celsius and a reaction time of about 10 minutes, alkaline pretreatment pH was better in preparing for enzymatic release of both xylose and glucose than acid pretreatment pH. Acid pretreatment was found to cause the solubilization of the hemicellulose fraction of the biomass, and liberates the 5-carbon monoscaccharides (xylose) into the liquid fraction; this reduces the available carbohydrates for ethanol processing in the pretreated solid biomass. The full study is published in the free access journal, Biotechnology for Biofuels (URL above). Biofuels Policy and Economicshttp://www.springerlink.com/content/b5w1r274627152r6/ Biofuels development has become a national policy agenda in many countries, with the hope of a promise to bring better energy security, and better environmental quality through the reduction of greenhouse gas (GHG) emissions. The reduction in GHG emissions from the use of transport biofuels could be possible, as long as this is not counteracted by the increase in emissions during the the production and processing of the biomass to biofuels. According to recent estimates, about 28% of the total greenhouse gas emissions are contributed from agriculture and land use change. After years of having biofuels at the forefront of national policy, can biofuels be really considered as an "advantageous energy source"? A recent review by researchers from the French National Institute for Agricultural Research (INRA) attempted to answer the question. In their review paper, they first presented various biofuels in terms of state-of-the-art production technologies, plus production/consumption rates. Then they described the political and economic frameworks which promote biofuels development, but fail to convince the stakeholders about the sustainability of biofuels. Finally, they address the issue of "biofuel quality" with focuses on greenhouse gas emissions and the potential of biofuels to mitigate climate change. Among the highlights of the review are: (1) the contribution of biofuels in the total energy consumption mix will be limited by scarcity of available land, unless new technologies can improve cost-effectiveness in biomass production yields, (2) bioenergy chains are location-specific; some may work in some locations, some may not. The maximum benefits of biofuels can be derived only if "the best appropriated bioenergy chain mix is chosen in accordance with local conditions", (3) harmonization of biofuel policies at an international level is important, in order to ensure "the overall complementarity of bioenergy chains, to provide a coherent framework for the markets and to control the sustainability of the systems", (4) carbon dioxide (or carbon-) sequestration would have a mitigating effect on the "significant part of global greenhouse gas emissions cannot be avoided". The full paper is published in the journal, Agronomy for Sustainable Development (URL above). http://www.sciencedirect.com/science/article/pii/S096195341000379X Researchers from the School of Chemistry and Chemical Engineering, South China University of Technology (China) report the use of "Emergy Analysis", for the assessment of the sustainability of cassava-based fuel ethanol (CFE) production in China. Emergy Analysis is considered to be a "valid approach to quantify both environmental and environmental costs" associated with a product, such as CFE. It could also help in the understanding of sustainability in a special way. "Emergy" (spelled with an "m") is described as a measure of the energy (of one kind) used in the past to make a product or service. According to Howard Odum (URL to paper in related information below), "emergy" is a measure of energy used in the past and thus is different from a measure of energy now. The unit of emergy (past available energy use) is the emjoule. The unit of "emjoule" is distinguished from the unit of "joule", which is used for available energy remaining. The Chinese researchers mentioned that "emergy analysis considers both energy quality and energy used in the past, and compensates for the inability of money to value non-market inputs in an objective manner". Thus it can be considered as a common unit that allows all resources to be compared on a fair basis. Emergy indices for the CFE production system (in terms of transformity, emergy yield ratio (EYR), environmental loading ratio (ELR), renewable energy ratio (RER), and emergy sustainability index (ESR)) indicate that cassava ethanol has a better sustainability compared to wheat-ethanol or corn-ethanol. From the perspective of sustainability, the researchers concluded that "CFE is a good alternative to substitute for oil". The full paper is published in the journal, Biomass and Bioenergy (URL above). Related information of "Emergy Analysis" "Emergy Evaluation", by Howard Odum http://www.oilcrisis.com/emergy/EmergyEvaluation.pdf |
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