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City trash plus farm leftovers
may yield clean energy
Monday, October 13, 2008
ALBANY, NY - Tomorrow`s household garbage might be blended with after-harvest leftovers from fields, orchards, and vineyards to make ethanol and other kinds of bioenergy, say scientists at the Agricultural Research Service Western Regional Research Center in Albany.
In most instances, agricultural wastes like rice straw, almond hulls, and the oversize outer leaves of iceberg lettuce will have to be pretreated before being used as a bioenergy resource. That`s according to Kevin Holtman, an ARS research chemist who`s working out the details of the garbage-to-gas approach.
The garbage, known as "municipal solid waste," or "MSW," would also be pretreated, he says.
The garbage would be processed in a jumbo-size autoclave, a device that acts something like a giant pressure cooker to convert the MSW into grey, lightweight clumps. The pretreated agricultural wastes and autoclaved MSW would then be transferred to a biofermenter. Yeasts and enzymes would be added, to make ethanol.
Mr. Holtman and colleagues David Bozzi, an engineering technician, and Diana Franqui, a microbiologist, are determining the best ways to use just water and heat, instead of hazardous chemicals, to pretreat the farm wastes, thus keeping the biorefining process environmentally friendly.
The team, part of the Bioproduct Chemistry and Engineering Research Unit at the Albany research center, is collaborating in the research and development venture with Comprehensive Resources, Recovery and Reuse Inc. of Reno, Nev., and with the Salinas Valley Solid Waste Authority.
Plans call for expanding the pilot facility at the landfill, where the autoclave is now installed, into a complete biorefinery.
"We`ll use new and off-the-shelf technologies to show that our system is flexible enough to incorporate a wide variety of waste streams, from season to season, harvest to harvest, year to year," says Mr. Holtman. "And even though the price and availability of the ag waste stream may vary, the MSW stream is endless and is a solid economic foundation to keep a biorefinery running.
"MSW is produced year round and is already collected and transported near population centers," he points out. "That means the biorefinery won`t be based on the tight economics associated with traditional crop-to-ethanol operations."
Besides producing biofuels, the biorefinery would also reduce the volume at landfills and minimize the need for new ones.
© 2008 Central Valley Business Times
Source: Central Valley Business Times
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