Green Car Congress: Transportable Pyrolysis Units to Convert Poultry Litter to Bio-Oil

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Transportable Pyrolysis Units to Convert Poultry Litter to Bio-Oil

19 August 2007

Researchers at Virginia Tech are developing transportable pyrolysis units that will convert poultry litter into bio-oil, providing an economical disposal system while reducing environmental effects and biosecurity issues.

Foster Agblevor, associate professor of biological systems engineering, presented the research during the 234th American Chemical Society National Meeting in Boston on August 19-23.

Agblevor is working with poultry growers to test technology that would convert poultry litter to three value-added byproducts: pyrodiesel (bio-oil), producer gas, and fertilizer.

The pyrolysis unit heats the litter until it vaporizes. The vapor is then condensed to produce the bio-oil, and a slow release fertilizer is recovered from the reactor. The gas can then be used to operate the pyrolysis unit, making it a self-sufficient system.

According to Agblevor, bio-oil yields ranged from 30 to 50 percent by weight, depending on the age and the bedding content of the litter. Bedding material that was mostly hardwood shavings yielded bio-oil as high as 62 percent by weight. The higher heating value of the poultry litter bio-oil ranged from 26 to 29 MJ per kilogram while bio-oil from bedding material was only 24 MJ per kilogram. The bio-oils had relatively high nitrogen content ranging from 4% to 7% by weight, very low sulfur content, below 1% by weight, and were very viscous.

The char yield ranged from 30% to 50% by weight, depending on the source, age, and composition of the poultry litter. The char also had a high ash content, ranging from 30% to 60% by weight, depending on the age and source of litter.

More than 5.6 million tons of poultry litter are produced each year in the United States. The litter consists of a mixture of bedding, manure, feathers, and spilled feed. According to Agblevor, current disposal methods, such as land application and feeding to cattle, are under pressure because of pollution of water resources due to leaching and runoff and concern about mad cow disease contamination in the food chain. There are also concerns that poultry litter can harbor such diseases as avian influenza.

Agblevor presented the paper, “Thermochemical conversion: A dual tool for bio-oil production and a solution to environmental waste disposal (FUEL 9),” as part of the session “Characterization of Fossil and Biofuels: Challenges and Progress.”

August 19, 2007 in Brief | Permalink | Comments (5) | TrackBack (0)