[GRRN]

["Jeff Morris" <jeff.morris@zerowaste.com>]

In reply to Priscilla Hayes:

Check out Table 1 in our study "Recycling versus incineration: an energy conservation analysis" published in Journal of Hazardous Materials (Elsevier, Amsterdam), Vol 47, 1996, pp. 277-293. Study is also serialized in my newsletter The Monthly UnEconomist for Feb-Apr 2000. The newsletter (which I'm way behind for putting up new issues right now but have about 6 almost ready to go) is available at no charge through our website www.zerowaste.com once you subscribe by sending us an email from our site and we return your password. 

The wetness of garbage in general is in part responsible for the inefficiency in converting the heat value of materials in garbage into energy in a waste-to-energy incinerator. In fact you only get about 15% of the energy out as electricity versus the heating value of the material that goes in (compared with around 33-35% when you're burning a fossil fuel in a steam electric power plant). 

But as you'll see when you look at Table 1, we couldn't figure out how to assign that wetness factor to particular materials, so food waste is shown as contributing something when its burned. But if one were able to assign the wetness of garbage to particular materials such as food waste, then their heat value would be much lower than shown in the table (while other materials heat value would go up in equal measure).

That doesn't give you an exact answer, but hopefully is some help. You could do an experiment there at Rutgers by getting some food waste (no paper or other non-food items) and getting someone in the engineering department to run a test on how much heat had to be added to burn it all up. Compare that against its material heating value of 6,048 kilojoules per kilogram (source: P.A. Vesilund and A.E.Rimer, Unit Operations in Resource Recovery Engineering, Prentice-Hall, Englewood Cliffs, NJ, 1981.) and you'd have your answer. I'd bet its close to zero or even negative if you try to burn it before its had a chance to sit around and dry out. Please let me know the results if you find someone in Rutgers' engineering dept. to do this experiment. Of course you'll have to do it for different kinds of meals (soup for lunch, etc.) and different types of cuisines. Sounds like a Ph.D. dissertation perhaps!!  

Good luck,
Jeff Morris

Dr. Jeffrey Morris
Sound Resource Management - Bellingham Office
112 Ohio Street, Suite 202
Bellingham, WA 98225

360-738-0255
360-738-0256 fax
www.soundresource.com or www.zerowaste.com
jeff.morris@zerowaste.com

From: Priscilla Hayes <hayes@AESOP.RUTGERS.EDU> 
>To: compost@compostingcouncil.org 
> 
>Does anyone have any information on studies that compare the btu/energy 
>value of food waste in incinerators with other MSW sent there?  I understand 
>that the high moisture content of the food waste makes it burn 
>inefficiently, without producing significant energy. 
> 
>Thank you. 
> 
>PRISCILLA HAYES, COORDINATOR 
>NEW JERSEY SOLID WASTE POLICY GROUP 
>DEPARTMENT OF AGRICULTURAL, FOOD AND RESOURCE ECONOMICS 
>RUTGERS UNIVERSITY--COOK COLLEGE 
>55 DUDLEY ROAD 
>NEW BRUNSWICK, NJ 08901-8520 
> 
>TELEPHONE: (732) 932-9155, ext.233 
> 
>FAX:  (732) 932-8887 
> 
>EMAIL:  hayes@aesop.rutgers.edu 
> 
>PLEASE VISIT OUR WEBSITE: 
> 
>http://aesop.rutgers.edu/~wastemgmt/ 
> 


*****************************************************
    To post to the greenyes list, send a letter to:
greenyes@earthsystems.org
    To unsubscribe, send a message to:
greenyes-request@earthsystems.org with the subject
unsubscribe.  If you have any problems, please
write to www@earthsystems.org.
    The GreenYes Listserv depends on reader support.
Your tax-deductible contribution in any amount can be
made by mail (check) or on the web (credit card) at
our website: http://www.grrn.org. Just click on the
"Support GRRN" button.
    GreenYes is archived at our website. Just click
on the "GreenYes Listserv" button for directions.
******************************************************