Chemists try to turn plant waste to fuel

Chemists try to turn plant waste to fuel


By Lidia Wasowicz


UPI Senior Science Writer


From the Science & Technology Desk


Published 8/28/2002 2:24 PM


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A team of chemical engineers has taken the first step to turning plant wastes into Earth-friendly hydrogen fuel that one day could keep the lights burning and engines running without depleting diminishing reservoirs of precious natural resources.





Hydrogen, the most plentiful element in the universe, already is employed in the chemical-processing, food and fuels industries, but at a cost two or three times that of natural gas. Because hydrogen rarely stands alone, however, harnessing its power means devising ways to break the ties that bind it to a wide variety of chemical compounds. In laboratory experiments, detailed in the British journal Nature, the researchers devised a new way to extract hydrogen from plant and animal matter, collectively known as biomass.





Professor James Dumesic, research scientist Randy Cortright and graduate student Rupali Davda at the University of Wisconsin in Madison developed a platinum-based catalyst, similar to that in automobile catalytic converters, that breaks down glucose — a sugar found in many fruits, animal tissues and fluids — into hydrogen gas, carbon dioxide and methane at a cool 200 degrees Celsius (392 degrees Fahrenheit). This is significantly lower — and more energy-efficient — than the 800 degrees C (1472 degrees F) required to produce hydrogen by traditional high-temperature steam-reforming technologies.





Steam reforming uses thermal energy to separate hydrogen from the carbon components in methane — a colorless, odorless, flammable gas obtained from natural gas — and methanol or wood alcohol. Methanol is used, among other ways, as a solvent for varnishes and lacquers, as antifreeze and as a gasoline extender in the production of gasohol.





“An entire industry has been developed worldwide taking methane and converting it into hydrogen,” said Esteban Chornet, principal engineer at the National Renewable Energy Laboratory in Golden, Colo., and professor of chemical engineering at Sherbrooke University in Quebec, Canada, who reviewed the findings.





“Renewable hydrogen production from biomass is being actively pursued in academic, institutional and industrial laboratories around the world, and the approach put forward (in the new study) represents progress in this direction,” Chornet told United Press International.





The advance should sound an encouraging note with the environmentally minded: hydrogen combustion releases abundant energy and only water as a waste product.





To sweeten the deal, the glucose derives from a non-polluting, plentiful source: plant and animal waste. Glucose is produced profusely from cornstarch — in the form of corn syrup as one example — and also can be made from sugar beets or paper mill sludge, cheese whey, corn stover and other low-cost biomass waste.





“(The findings) provide experimental evidence that simple biomass-derived molecules, such as glucose and glycerol (derived from fats), can be treated to produce hydrogen with reasonable efficiency,” Chornet and Stefan Czernik, senior research scientist at the Colorado lab, concluded in a commentary on the research.





“The authors suggest that, with some additional effort, their technique could also be technologically and commercially viable,” they wrote.





For now, the residue is broken down by bacteria in a process too complex, inefficient and costly on a mass scale to capture much industrial attention, a drawback the researchers are determined to overcome. Dumesic and team have visions of harnessing hydrogen with a more-efficient, less-expensive method than bacterial fermentation, utilizing waste p