|
|||
 |
|||
 |
|||
|
|||
News and Trendshttp://www.sciencemag.org/cgi/content/full/314/5805/1598 A research team at the University of Minnesota has released a new study after its publication on the life-cycle accounting assessments of corn ethanol and soybean biodiesel as viable fuel alternatives (Biofuels Supplement 2006 November 24). In the new study, “Low Input High Diversity” (LIHD) plants have been identified as a third major class of biomass sources for biofuel production. (The first two major classes are (a) monoculture crops on like corn, soybean, sweet sorghum, etc, and (b) waste biomass like straw, baggasse, corn stover, etc). Published in the 2006 December issue of the journal Science, the study shows that biofuels produced from LIHD native grassland perennials provide the following benefits: (1) more usable energy and net energy gain per hectare compared to corn ethanol, (2) net carbon-negative biofuel product (i.e., reduces greenhouse gases), in contrast with corn ethanol and soybean biodiesel which are “carbon-sources” (net increase in greenhouse gases, but lower than fossil fuels), (3) reduction of agricultural inputs (i.e., agrochemicals) compared with food-based biofuels, (4) utilization of abandoned, non-productive lands, thereby avoiding competition for fertile lands normally used for food production. The paper provides quantitative data related to the above benefits.
(Abstract of research article and link to conditional access to full paper: http://www.sciencemag.org/cgi/content/abstract/314/5805/1565?maxtoshow=&HITS=10&hits=10&RESULTFORMAT= Related articles: Scientists from the Massachusetts Institute of Technology (MIT) have reported the successful engineering of a high-ethanol fermenting yeast (Saccharomyces cerevisiae) with improved glucose/ethanol tolerance, by a technique called “global transcription machinery engineering (gTME)”. Reported in the September issue of Science, the authors described global transcription machinery engineering (gTME) as “an approach for reprogramming gene transcription to elicit cellular traits (phenotypes) that are important for technological applications”. By using this approach, the researchers obtained a high-ethanol tolerant yeast strain which could ferment glucose to ethanol that is 50% higher than normal yeast. The method, the authors report, can “provide a route to complex phenotypes that are not readily accessible by traditional methods”. Energy Crops and Feedstocks for Biofuels Production
Research article: http://www.ars.usda.gov/is/pr/2006/061101.htm?pf=1 Related articles: Pennycress (Thlaspi arvense) is an annual winter weed in soybean fields that farmers in the Midwestern United States find little use of. However, this plant may soon be of value, due to research efforts at the U.S. Department of Agriculture, Agriculture Research Service (ARS) Center for Agricultural Utilization Research (NCAUR). The research team, headed by Terry Isbell, reports the following characteristics of pennycress seeds which make it a potential source for biodiesel: (a) an oil content of 36% to 40%, and (b) a long chain fatty acid profile comparable to well known biodiesel sources like soybean or sunflower oils. By treating pennycress as another crop rather than a weed, the researchers noted that farmers would be able to produce fuel in the winter from pennycress and food in the summer from soybeans. Isbell and his team are doing pilot scale conversion of pennycress oil to biodiesel and will subsequently analyze the characteristics of the fuel product.
Research article: http://mic.sgmjournals.org/cgi/content/full/152/9/2529 German scientists have metabolically engineered E. coli so that it can produce biodiesel in the form of fatty acid ethyl esters (FAEE). They expressed in E. coli, the genes for ethanol formation (derived from Zymomonas mobilis) and subsequent esterification of the ethanol with acyl groups of coenzyme A thioesters of fatty acids (from Acinetobacter baylyi ). The biodiesel product, called “microdiesel” could be produced by aerobic fermentation of the engineered E. coli in the presence of glucose and oleic acid. The main component of the FFAEs is ethyl oleate, with ethyl palmitate and ethyl palmitoleate as minor side products. In fed batch fermentations, a microdiesel concentration of 1.28 grams per liter FAEE was obtained. The FAEE constituted about 26% of the cell dry. Biofuels Processinghttp://aiche.confex.com/aiche/2006/techprogram/P58945.HTM Scientists from the University of Mississippi explored the pretreatment of corn stover (lignin depolymerization) prior to ethanol fermentation by bacterial conditioning. (Bacterial conditioning can be considered as partial degradation of lignocellulosics in corn stover by the addition of bacteria with lignolytic/cellulolytic activity. This would make the ethanol fermentation step easier). The bacterial conditioning agents were inocula prepared from guts of insects that are known to digest wood. Inocula were obtained from cultures from dissected guts of termites, beetles, etc. From weight loss experiments during solid substrate fermentations (SSF), four out of 14 sources that were obtained from midgut were found to show weight loss in the pretreated corn stover; negligible weight loss was observed in untreated corn stover. Further studies are reported to be done to characterize bacterial flora in the insect guts and to determine their response to operating conditions like pH and temperature..
Research article: http://www.ccee.iastate.edu/research/projects/projectid/1140535067 The conventional dry milling process of corn does not often convert all of the starch to available sugars which can then be fermented to ethanol. In order to improve ethanol yields, a team of scientists at the Iowa State University, led by David Grewell, are integrating ultrasonics into dry corn milling. Ultrasound (high frequency sound waves) is applied to the corn mash and cavitation (rapid collapse of gas bubbles) in the liquid causes the break-up of corn particles into much finer sizes. This exposes more of the starch to the enzymes responsible for the degradation of the starch to simple sugars. The increase in the conversion of starch to simple sugars results in increased activity of ethanol fermentation. Laboratory experiments have shown that after ultrasonic treatment, the original corn particle size was reduced 50-fold. Reduction in corn particle size exposes more surface area for enzymatic attack, resulting in a 30% increase in the rate of sugars (enzymatically) released from the corn starch. A patent application for the technology has been filed.. Biofuels Policy and Economicshttp://www.nexant.com/news/index.html Nexant, Inc. has published a study (based on technoeconomic modeling), which looks into the “current, emerging, and future technologies” in biofuels. Some of its findings and conclusions are: (1) biodiesel (as fatty acid methyl ester) is seen as a “transition technology”, which would substitute only a small fraction of the global demand for diesel, (2) the next phase in bioethanol development would be ethanol fermentation of substrates obtained from hydrolysis of biomass feedstocks, (3) biofuels production from themochemical processing will be a major technology player for producing “gasoline and diesel range biofuels”.. http://biopact.com/2006/07/look-at-africas-biofuels-potential.html A summary of two reports related to the analysis of Africa’s biofuels potential can be read at the Biopact website. Biopact is an organization of European and African citizens whose efforts are channelled toward the establishment of a “mutually beneficial 'energy relationship' based on biofuels and bioenergy”. The summary is based on the analysis by the Copernicus Institute at the University of Utrecht. The calculation of the biofuel potential was based on some factors such as “demographic trends, the demand for food, fiber and wood products, and changes in land-use patterns.” Among the findings of the report were: (a) sub-Saharan Africa has the largest energy potential (estimated maximum is about 410 x 1018 joules of energy), (b) under a high productivity scenario, the biofuel production potential of the planet is said to be several times larger than the total amount of energy that can be obtained from both fossil fuels and nuclear power, (c) Africa still stands to become a large biofuels producer, even when the worst-case climate change predictions are taken into account |
|||
