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[greenyes] The environmental impacts of recycling glass
Hi all ~

I have seen various computer models that tally up the environmental impacts
of recycling glass. The latest -- and very clearly stated -- is in the 2001
edition of "Integrated Solid Waste Management: A Life Cycle Inventory", by
Forbes McDougall, et. al. 

On pages 441-442, Table 22.3 compares about 50 parameters, and I would be
glad to copy and either mail or fax the tables to people.

Here are some of the data, expressed on a metric ton basis of finished

   Parameter			Virgin 		Recycled

Engery (GJoules)	 	14.5		    11.04

Carbon dioxide		 	145,600	  	   57,000

NOx			  	1500		      2880

Suspended solids - water	7760		        796

Chlorides -water			 99,900		     8,410

Total organics - water		    68.5                      80.7

On the energy issue, a gigajoule is a billion joules and there are 1054
joules in a BTU. Thus, making a metric ton of glass from recycled material
saves about 3.3 million BTUs, or 3 million BTUs per US ton, according to
this source. In comparison, according to data in the March/April 1981 issue
of BioCycle, an article by Jerry Powell puts the savings at 2.95 million
BTUs a ton, although the article has alternative estimates of 1.3 to 2.5
million BTUs. In the same article, it is noted that a gallon of gasoline has
128,000 BTUs. 

The data do not include the impacts of collection, processing or
transportation, which is included in other sections of the book. 

Other LCA models also exist, including one by Argonne National Labs, which
looked at the distance to which cullet can be transported before the energy
of transportation exceeds the energy savings. If  I can find the data of
these other studies, I will let people know.

It should be noted that on a per ton basis, the energy savings from glass
are less than the savings from all other products listed in the above book.
The book listed above does not evaluate the relative importance of the
various environmental impacts nor does it look at a possible economic value
for the individual impacts, as is done in environmental valuation studies.

John Reindl, Recycling Manager
Dane County, WI 

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