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News and Trends
(full access to journal article may require payment or subscription) Researchers from the University of Massachusetts (United States) report the use of "Expert Elicitation" for analyzing the relationship between "US Government Research & Development funding and the likelihood of achieving advances in cellulosic biofuel technologies". Expert Elicitation has been defined as a "systematic process of formalizing and quantifying (in terms of probabilities) experts' judgments about uncertain quantities". It finds use as a support tool in decision making and regulatory analyses. Six distinct technology paths for the conversion of cellulosic biofuels into three different end-products (ethanol, biodiesel, or biogasoline) were considered. These paths included two selective thermal processing paths (pyrolysis, liquefaction), two hydrolysis paths (aqueous processing, fermentation) and two gasification paths (syngas conversion to ethanol, syngas conversion to biodiesel). Technological endpoints included cost, capacity and efficiency. Results showed that despite disagreements among experts, the "patterns of disagreement" suggested some distinct strategies. Selective thermal processing paths (for bio-oil production from cellulosic feestocks) had generally the "highest expected benefits per dollar funding". This was attributed to the high favorable endpoints of bio-oils and highest probabilities of success. Moderate investments in the hydrolysis paths were also found to be efficient. The full results of the study are published in the journal, Energy (URL above). Related information on Expert Elicitation: http://www.nusap.net/downloads/reports/Expert_Elicitation.pdf. http://www.udel.edu/udaily/2011/apr/rosenthal-greenhouse-gas-042611.html Joel Rosenthal, a chemist at the University of Delaware (United States), was awarded the Ralph E. Powe Junior Faculty Enhancement Award to pursue the novel research on the catalytic conversion of carbon dioxide into biofuel precursors and useful chemicals. The award was given by the Oak Ridge Associated Universities (ORAU), a consortium of 98 Ph.D.-granting universities. According to the University of Delaware news release, "Rosenthal and his team are designing electrocatalysts from metals, such as nickel and palladium. that will freely give away electrons when they react with carbon dioxide, thus chemically reducing this greenhouse gas into energy-rich carbon monoxide or methanol". This can be considered as a chemical route for the conversion of carbon dioxide into materials for biofuel production. The photosynthetic route through the use of plants is also another route for production of biofuel materials. According to Rosenthal, "carbon monoxide is an important precursor to liquid hydrocarbons in the energy arena, in addition to its applications as an industrial chemical for producing plastics to detergents to the acetic acid used in food preservation, drug manufacturing and other fields". Energy Crops and Feedstocks for Biofuels Production
Scientists from the Research Center for Sustainable Development in Industry and Energy and the Department of Chemical Engineering, Industrial University of Santander (Colombia) attempted to implement "design and process integration to compare several biorefinery topologies using the typical mass flow rate of residual biomass produced by the sugar industry". They considered four technological routes for the generation of ethanol from sugarcane bagasse, and simulated each of these processes by ASPEN PLUSTM software, using the typical mass flow rate of residual biomass produced by the sugar industry. A basis of 1200 ton per day production was used. Their results showed that the production route involving organic solvent treatment of the biomass, followed by simultaneous saccharification and co-fermentation (SSCF) gave the highest ethanol yield. The high ethanol yields were attributed to near-complete hydrolysis of hemicellulose, the high yield of xylose, and lignin solubilisation. On the other hand, the process route involving catalyzed steam explosion, followed by SSCF gave the lowest ethanol yield, due to poor lignin solubilisation. Heat integration methodologies were found necessary to improve energy efficiency in the processes. The full paper is published in the journal, Chemical Engineering Research and Design (URL above). Biofuels Processing
http://www.biotechnologyforbiofuels.com/content/4/1/10/abstract Scientists from the Department of Chemical Engineering, Lund University (Sweden) mention that mixing is an important consideration in the scale up of the enzymatic hydrolysis step in the conversion of lignocellulosic biomass for ethanol production. Enzymatic hydrolysis is the conversion of carbohydrate polymers in the pretreated lignocellulosic biomass (mainly cellulose and hemicelluloses) into (ethanol-fermentable) sugars by the use of enzymes. Pretreated biomass with a high water-insoluble-solids (WIS) content is preferred during enzymatic hydrolysis, because it usually results in higher ethanol yields after fermentation. However, a high WIS increases viscosity of the reaction system during enzymatic hydrolysis and can increase mixing power requirements. This would result in a higher energy cost . The University of Lund scientists investigated the relationship between mixing intensity and enzymatic hydrolysis performance of steam-exploded spruce in stirred tank reactors. Spruce trees are coniferous trees belonging to the genus Picea, and have been traditionally cultivated for paper and construction uses. These trees have also been considered as a potential biofuel feedstocks. The researchers confirmed the strong effect of mixing enzymatic hydrolysis, and interplays with both enzyme loading and hydrolysis residence time. This interplay can be harnessed to obtain a high degree of reaction performance. The full-results of the study are published in the open access journal, Biotechnology for Biofuels (URL above). Biofuels Policy and Economics
(full access to journal article may require payment or subscription) Interesting insights into the "evolving technological interdependence for China's emerging biofuel industry" have been reported recently by Mei-Chih Hua of the National Tsinghua University (Taiwan) and Fred Phillips of the Alliant International University (United States). The full paper is published in the journal, Technological Forecasting & Social Change (URL above). The researchers applied "two-stage interactive data collection methods" and used the European Patent Office worldwide patent database for their study. They found that technological developments in China's biofuel industry was dependent on fields related to food or non-alcoholic beverages before the year 2000, and this shifted to the biochemical field (microorganisms, enzymes) beyond the year 2000. They see China's biofuel technology as one that is "largely based on the evolutionary strength of the foodstuff and chemical fields". Development of biofuel technology was also observed to be led by Chinese universities, rather than by public research institutes. Based on patent map and technology trajectory analyses, China's biofuel technology is found to be "application-oriented and highly intertwined with the pharmaceutical industry" since the year 2000.
http://pubs.acs.org/doi/abs/10.1021/es102597f Researchers from the Massachusetts Institute of Technology (MIT) report that in the Life Cycle Analysis (LCA) of biofuels, "changing key parameters can dramatically change the total greenhouse gas emissions from a given biofuel". LCA is a tool that is commonly used for the assessment of net energy yields and greenhouse gas emissions of a particular biofuel, as it goes through cultivation, processing and eventual use (combustion) as a biofuel product. Their study showed that "variability in life cycle analysis (LCA) is inherent due to both inexact LCA procedures and variation of numerical inputs". Using examples from the production of biofuels from 14 different feedstocks, they were able to show the magnitudes and types of variabilities in their corresponding LCA's. Sources of variability have been attributed to three categories: (1) pathway specific, (2) coproduct usage and (3) allocation/land use change. Subjective biases in the methodologies for coproduct usage and allocation, for example, are an important sources of variability. These can be minimized, according to the researchers, through the "application of a consistent analysis methodology across all fuel options". They also recommend that "LCA results should be presented as a range instead of a point value". The full study is published in the Environmental Science and Technology journal (URL above). |
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