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August 15, 2011 - Volume 89, Number 33
- p. 12
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Forensic Chemistry: A new method could increase the number of explosives detected by airport screeners.
Trade: U.S. companies complain of market dumping by China.
Layoffs follow similar moves by Amgen, AstraZeneca.
Environment: Ban to halt export of hazardous waste to developing world.
Penrose (Parney) Albright will direct DOE national lab.
Toxic Exposure: Mercury isotopes in human hair illuminate dietary and industrial sources.
Cancer Biochemistry: Mass spectrometry follows the metabolism of very long fatty acids in cancer cells.
First generation: Ethanol and biodiesel are commercially available first-generation biofuels. Ethanol comes from the starches and sugars in food crops such as corn and sugarcane. Sugarcane is a more efficient source than corn and the one on which Brazil, which is second to the U.S. in producing ethanol biofuel, has built its biofuels industry. The U.S. ethanol industry largely rests on corn. First-generation biodiesel mostly comes from rapeseed (canola), but soy and palm also contribute. According to biofuels expert Anselm Eisentraut at the International Energy Agency, ethanol from corn and sugarcane can “be produced at prices competitive with fossil fuels today.”
Second generation: Experts believe cellulosic ethanol made from inedible plant matter, such as switchgrass and wood trimmings, will be the next type of biofuel to enter the market. Its advantage is the feedstocks can be more environmentally friendly and economically sustainable than food-based biofuels. The biggest technical challenge, however, is economically converting molecules in plant cell walls into biofuels. It’s a challenge where “there’s a huge potential for chemical engineers to contribute” to bring down costs of processing, points out Alena Buyx, assistant director of the secretariat at the Nuffield Council on Bioethics, a U.K.-based think tank. Biodiesel also is a second-generation biofuel when it’s produced from plant matter by a variety of methods. The most famous one—Fischer-Tropsch synthesis—converts a mixture of carbon monoxide and hydrogen into liquid hydrocarbons; it was used by the Germans during World War II to produce petroleum substitutes.
Third generation: This generation of biofuels is sometimes referred to as the “advanced” generation. Fuels in this category are generally oils, such as jet fuel, derived from algae and other aquatic species. The hydrocarbon molecules in these fuels often pack more energy per gallon than do first- or second-generation biofuels. Like second-generation biofuels, the third generation of biofuels aims to not compete with food for land; to not harm the environment; to have high energy yields with low inputs of water, land and fertilizer; and to have cost-effective production.
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