[Gasification] Pyrolysing compost to make fuel

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Iowa  State Researchers Convert Farm Waste To Bio-Oil  8/1/2006   
Nevada, IA - Samy Sadaka reached into a garbage bag, picked up a  mixture of 
cow manure and corn stalks, let it run through his fingers and  invited a 
visitor to do the same.  
It wasn't that bad.  
That mix of manure and corn stalks had spent 27 days breaking down in a  
special drying process. The end result looked like brown yard mulch with  lots of 
thin fibers. There wasn't much smell. And it was dry to the touch.   
"That's about 20 percent moisture," said Drew Simonsen, an Iowa State  
University sophomore from Quimby who's working on the research project led  by 
Sadaka, an associate scientist for Iowa State's Center for Sustainable  
Environmental Technologies.  
Other Iowa State researchers working on the project are Robert Burns,  an 
associate professor of agricultural and biosystems engineering; Mark  Hanna, an 
Extension agricultural engineer; Robert C. Brown, director of  the Center for 
Sustainable Environmental Technologies and Bergles  Professor in Thermal 
Science; and Hee-Kwon Ahn, a postdoctoral researcher  for the department of 
agricultural and biosystems engineering.  
The project is being supported by $190,000 in grants from the Iowa  
Biotechnology Byproducts Consortium.  
The researchers are working to take wastes from Iowa farms -- manure  and 
corn stalks -- and turn them into a bio-oil that could be used for  boiler fuel 
and perhaps transportation fuel.  
"The way I see manure, it's not waste anymore," Sadaka said. "It is  
bio-oil."  
But it takes a few steps to make that transformation.  
First, the manure needs to be dried so it can be burned. Sadaka's idea  for 
low-cost and low-odor drying is to mix the manure with corn stalks,  put the 
mix in a big drum, use a small blower to keep the air circulating  and use an 
auger to turn the mixture once a day. Within about five days,  bacteria and 
fungi working to decompose the mix have naturally raised the  temperature to about 
150 degrees Fahrenheit. Within another 20 days or so  the moisture content is 
down from 60 percent to about 20 percent. Sadaka  calls the process 
bio-drying.  
That makes it possible to move to the next step: rapidly heating the  mixture 
in a bubbling, fluidized bed reactor that has no oxygen. It's a  process 
called fast pyrolysis. The process thermochemically breaks the  molecular bonds in 
the mixture. It produces charcoal that can be used to  enrich soil. And it 
produces vapors that are condensed to a thick, dark  bio-oil.  
Preliminary tests indicate every kilogram of dried mixture produces .2  to .5 
kilograms of bio-oil depending on the operating conditions.  
Sadaka said the energy content of dry manure is 12 to 18 gigajoules per  ton. 
Canada's Office of Energy Efficiency says one gigajoule of  electricity will 
keep a 60-watt bulb continuously burning for six months.  Sadaka figures if 
half the animal manure in the country were processed  into bio-oil, that would 
produce the equivalent of 45 million tons of oil.   
Sadaka is experimenting with the process in 900-liter drums at the Iowa  
Energy Center's Biomass Energy Conversion Center in Nevada. So far, he has  dried 
a mixture of cow manure and corn stalks. Next he'll test the process  with 
poultry manure. And then he'll try pig manure.  
This fall he'll work with Dave Struthers, a Story County farmer whose  family 
runs a 1,000-sow, farrow-to-finish farm east of Collins, to try the  
bio-drying process on a farm.  
Struthers said the farm's pigs live in hoop buildings and their manure  is 
mixed with bedding material. That mixture is applied to the surface of  crop 
ground as fertilizer.  
He's working with Sadaka to convert some of the farm's manure into  bio-oil 
because he supports alternatives to petroleum.  
"And there may be more value in using manure as a fuel source than a  
fertilizer source," Struthers said.  
Sadaka is convinced this process can help solve some of Iowa's  challenges 
with agricultural wastes while producing renewable energy. "My  goal," he said, 
"is to keep on demonstrating this for all the farmers  around."  
SOURCE: Iowa State  University