Bio-Fuels

"UCLA engineers develop new metabolic pathway to more efficiently convert sugars into biofuels"
2013-10-03 from "SPX" newswire [http://www.biofueldaily.com/reports/UCLA_engineers_develop_new_metabolic_pathway_to_more_efficiently_convert_sugars_into_biofuels_999.html]:
The paper's other author is Tzu-Shyang Lin, who recently received a bachelor's degree from UCLA in chemical engineering.
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 Los Angeles CA -
UCLA chemical engineering researchers have created a new synthetic metabolic pathway for breaking down glucose that could lead to a 50 percent increase in the production of biofuels. The new pathway is intended to replace the natural metabolic pathway known as glycolysis, a series of chemical reactions that nearly all organisms use to convert sugars into the molecular precursors that cells need. Glycolysis converts four of the six carbon atoms found in glucose into two-carbon molecules known acetyl-CoA, a precursor to biofuels like ethanol and butanol, as well as fatty acids, amino acids and pharmaceuticals. However, the two remaining glucose carbons are lost as carbon dioxide.
Glycolysis is currently used in biorefinies to convert sugars derived from plant biomass into biofuels, but the loss of two carbon atoms for every six that are input is seen as a major gap in the efficiency of the process. The UCLA research team's synthetic glycolytic pathway converts all six glucose carbon atoms into three molecules of acetyl-CoA without losing any as carbon dioxide. The research is published online Sept. 29 in the peer-reviewed journal Nature.
The principal investigator on the research is James Liao, UCLA's Ralph M. Parsons Foundation Professor of Chemical Engineering and chair of the chemical and biomolecular engineering department. Igor Bogorad, a graduate student in Liao's laboratory, is the lead author. "This pathway solved one of the most significant limitations in biofuel production and biorefining: losing one-third of carbon from carbohydrate raw materials," Liao said. "This limitation was previously thought to be insurmountable because of the way glycolysis evolved."
This synthetic pathway uses enzymes found in several distinct pathways in nature. The team first tested and confirmed that the new pathway worked in vitro. Then, they genetically engineered E. coli bacteria to use the synthetic pathway and demonstrated complete carbon conservation. The resulting acetyl-CoA molecules can be used to produce a desired chemical with higher carbon efficiency. The researchers dubbed their new hybrid pathway non-oxidative glycolysis, or NOG. "This is a fundamentally new cycle," Bogorad said. "We rerouted the most central metabolic pathway and found a way to increase the production of acetyl-CoA. Instead of losing carbon atoms to CO2, you can now conserve them and improve your yields and produce even more product."
The researchers also noted that this new synthetic pathway could be used with many kinds of sugars, which in each case have different numbers of carbon atoms per molecule, and no carbon would be wasted. "For biorefining, a 50 percent improvement in yield would be a huge increase," Bogorad said. "NOG can be a nice platform with different sugars for a 100 percent conversion to acetyl-CoA. We envision that NOG will have wide-reaching applications and will open up many new possibilities because of the way we can conserve carbon." The researchers also suggest this new pathway could be used in biofuel production using photosynthetic microbes.


"Solving ethanol's corrosion problem may help speed the biofuel to market" 
2013-10-03 from "SPX" newswire [http://www.biofueldaily.com/reports/Solving_ethanols_corrosion_problem_may_help_speed_the_biofuel_to_market_999.html]:
The paper, "Effect of Oxygen on Ethanol SCC Susceptibility, Part 2: Dissolution-Based Cracking Mechanism," written by Liu Cao, G.S. Frankel, and N. Sridhar, appears in NACE International's journal, CORROSION, Sep. 2013, Vol. 69, No. 9, pp. 851-862.
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Houston, TX  -
If we're to meet a goal set by the U.S. Environmental Protection Agency's Renewable Fuels Standard to use 36 billion gallons per year of biofuels-mostly ethanol-the nation must expand its infrastructure for transporting and storing ethanol. Currently, ethanol is transported via trucks, trains, and barges. For the large volumes required in the future, transportation by pipeline is considered to be the most efficient method to get it to customers. The integrity and safety of pipelines and storage tanks is crucial, because ethanol is both flammable and, at certain concentrations, can cause adverse environmental impacts.
"One of the most important concerns with regard to the integrity of pipelines and tanks is the propensity of ethanol at concentrations above 20 volume percent in gasoline to cause cracking of steel," explains Narasi Sridhar, vice president, director of the materials program at Det Norske Veritas. "This phenomenon is called stress corrosion cracking."
The Pipeline Research Council International, a consortium of pipeline companies, and the U.S. Department of Transportation's Pipeline and Hazardous Materials Safety Administration funded intense research to find the cause of cracking of steel in ethanol from 2005 through 2012. "We found that dissolved oxygen in ethanol causes cracking and if oxygen can be removed, cracking can be prevented. This and other engineering measures can form the basis for safe transport of ethanol," says Sridhar.
The fundamental mechanism of how oxygen causes cracking of steel is described in a paper by Liu et al., published in CORROSION journal. This paper is significant because it was extremely difficult to tease apart the fundamental processes occurring in ethanol due to its low electrical conductivity. By developing novel techniques, the researchers found that oxygen has two effects that conspire to cause the cracking of steel.
"The first effect is that oxygen protects most of the steel surface. It may seem counterintuitive that protection can lead to cracking of steel, but by protecting most of the steel surface oxygen channels all the degradation to occur on isolated areas of steel that is highly stressed. Such focused degradation results in rapid penetration of steel," says Sridhar. "The other effect of oxygen is that it pushes the corrosion processes to occur faster in the unprotected portion of the steel. Corrosion is an electrochemical process in which two electrons are emitted into the steel for every atom of iron corroding. Oxygen absorbs the electrons emitted by steel corrosion and propels the steel to corrode faster."
The practical implication of this paper is that it's now possible to prevent stress corrosion cracking without resorting to completely removing oxygen from ethanol, which is expensive to do. Sacrificial metals, for example, can be used to prevent cracking. Inhibitors can also be used to prevent cracking by reforming the protective film on steel faster.