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Views on Alternative Fuels Differ

May 12, 2009
Are biofuels a boon or a black hole for chemical engineering?
A special issue of Biofuels, Bioproducts and Biorefining focusing on the role of biomass in the United States’ energy future concludes that cellulosic biofuels offer similar, if not lower costs, and very large reductions in greenhouse gas emissions compared to petroleum-derived fuels. The journal hopes that the issue’s content, which includes a comparative analysis of more than a dozen mature technology biomass refining scenarios, will make a major contribution to the ongoing debate on the future potential of biofuels in the USA. Professor Lee Lynd from the Thayer School of Engineering at Dartmouth College, Hanover, N.H., is co-author of five of the eight papers in the special issue. “We conclude that mature biomass refining is highly competitive with the fuels currently available, based on all the factors considered,” he says. “The most promising class of processes we analyzed combined the biological fermentation of carbohydrates to fuels with advanced technologies that thermochemically convert process residues to electrical power and, or, additional liquid fuels. One of our important findings, which contradicts conventional wisdom, is that similar greenhouse gas emission reductions on a per ton biomass basis are anticipated for the production of liquid fuels and electricity via mature technology.” The researchers also found that the mature cellulosic biofuel technologies analyzed potentially can provide efficiencies on a par with petroleum-based fuels; require modest volumes of process water; and achieve production costs consistent with gasoline when oil prices are at about $30 a barrel. Three of the papers are available on the journal’s Web site (http://www.interscience.wiley.com/biofpr). “By making key papers in this series free we hope that this special issue of the journal will provide greater understanding of the exciting possibilities that biofuels can offer and help policy makers to make informed choices," concludes Lynd. Meanwhile, in Ghana attention is now focused on two species of tree. Jatropha curcas and Azadirachta indica, also known as neem, have seeds with high oil content. Researchers at Kansas State University (KSU), Manhattan, Kansas, believe the oil will be of particular help in Ghana, which suffers with a short rainy season, desertification, and constant fuel shortages. Neem seeds were selected following a study by KSU Biology Division scientists, with funding by its African Studies Center. The two trees would be cultivated specifically for biodiesel production on land that is unsuitable for growing food. Wayne Yuan, KSU assistant professor of biological and agricultural engineering, has offered his biodiesel reactor design and conversion expertise when funding becomes available for a proposed biodiesel extraction plant in Ghana. More about the potential for neem seed oil as a biofuel can be found at www.k-state.edu/africanstudies/2009symposium/. However, doubts remain about the efficacy of biofuels. In the April issue of Conservation Biology , a study finds that biofuels could hasten climate change. Headed by research scientist Finn Danielsen, the study says that it will take more than 75 years for carbon emissions saved through the use of biofuels to compensate for carbon lost when biofuel plantations are established on forestlands. If the original habitat was peatland, carbon balance would take more than 600 years to achieve. Conversion of forest to oil palm — a growing source of biofuel — also results in significant impoverishment of both plant and animal communities, says the study. Other tropical crops suitable for biofuel use, like soybean, sugar cane and jatropha, are all likely to have similar impacts on climate and biodiversity, it claims. “The EU and the U.S. should only import and subsidize biofuel from guaranteed sustainable productions and only from countries which can demonstrate that their forests are sustainably managed,” says Danielsen. And Friends of the Earth (FoE), London, published a report on April 15, which suggests that biofuels could have doubled carbon dioxide emissions of fossil fuels they replace — equivalent to putting 500,000 extra cars on the road. Conservative estimates show U.K. mandates for additional biofuels, that came into effect in April 2008, could have caused 1.3 million metric tons of extra carbon dioxide emissions, according to the group. The new figures come on the day the U.K. government increased the amount of biofuels in petrol (gasoline) and diesel from 2.5 to 3.3%. “Until ministers can do their sums properly and prove that growing crops for fuel actually cuts carbon, the government should stop biofuels being added to U.K. petrol and diesel. Trying to cut emissions by adding biofuels to petrol is like trying to cut down on beer by lacing your pints with vodka,” observes Andy Atkins, the group’s executive director. For an update on biofeedstocks, see http://www.ChemicalProcessing.com/articles/2009/094.html.Seán Ottewell is Chemical Processing's Editor at Large. You can e-mail him at[email protected].

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