A group of researchers in the Thayer School of Engineering at Dartmouth and society Mascoma Corporation of Lebanon, New Hampshire, has discovered a new method for producing large quantities of cellulosic ethanol, a leading candidate to be a safe and sustainable fuels derived from oil for vehicular traffic.

For the first time the group has changed with genetically engineered thermophilic bacteria - that is able to grow under conditions of high temperature - so that the body produces ethanol as the only product of fermentation processes.

"Our discovery represents a possible way to facilitate the conversion of cellulosic biomass unpublished, including those consisting of wood, grass and other waste materials, into ethanol," said Lee Lynd, professor of environmental design of the Thayer School that has developed Methodical and has signed an article in the journal "Proceedings of the National Academy of Science."

"The method we have developed is already profitable in the short term, since the cellular enzymes typically used in the production of ethanol are expensive, but can be increased by using the less expensive modified organisms." According to Lynd, the present is only a first step , A demonstration of feasibility, pending a future development of microbes that produce ethanol from cellulosic biomass without the addition of enzymes.

In the United States all the ethanol used as a gasoline additive derived from corn, despite biomass are widely recognized as raw materials cheaper, but you have a technology economically viable. The cellulosic ethanol is available on a large scale, does not include materials that may be intended for and is economically competitive with oil.

Among the environmental benefits, there is a sustainable carbon cycle: the net contribution to emissions of greenhouse gases in this case is practically zero, from the time that the carbon emitted during the combustion of ethanol is equal to the carbon sequestered during the growth of biomass . In addition, ethanol can be used for feeding of hydrogen fuel cells. (fc)

http://lescienze.espresso.repubblica.it/articolo/articolo/1333175

Vehicles with fuel ethanol (E85) could reduce atmospheric concentrations of two carcinogens such as benzene and butadiene, but increase those of two other toxic compounds such as formaldehyde el'acetaldeide.

Ethanol is considered - especially in the United States - a clean fuel and engines of many innovative projects focusing on the exploitation of this alcohol. But if it were adopted on a large scale in transport, the number of deaths and hospitalizations due to pulmonary diseases increase.

this is the conclusion of a study conducted at Stanford University and published online in the journal Environmental Science & Technology (ES & T) signed by Mark Z. Jacobson, "Effects of Ethanol (E85) versus Gasoline Vehicles on Cancer and Mortality in the United States."
"Ethanol is being promoted as clean and renewable fuel that could help reduce global warming," says Jacobson, professor of civil and environmental engineering. "But our results show that the use of mixtures with a high alcohol content of this poses a health risk as high petrol, which currently has a health impact already quite important."

In the course of the study was used a sophisticated computer model to simulate air quality in 2020, when it is expected that the car all'etanolo are already widely available on the market. Were compared two scenarios: one where the fleet is powered by petrol and the second in which the same fleet is powered by E85, a blend very common with 85 percent ethanol and 15 percent gasoline.

"We found that ethanol-fueled vehicles could reduce atmospheric concentrations of two carcinogens such as benzene and butadiene, but increase those of two other toxic compounds such as formaldehyde el'acetaldeide," concluded Jacobson. "As a result, the risk factors for cancer in the two cases are similar. However, in some parts of the country, the E85 would increase ozone levels. "

Source: http://lescienze.espresso.repubblica.it/articolo/articolo/1300025
http://pubs.acs.org/cgi-bin/sample.cgi/esthag/2007/41/i11/html/es062085v.html

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