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Re: [greenyes] The environmental impacts of recycling glass
Thanks to John Reindl for supplying yet another piece of credible testimony underscoring the limited environmental benefits of recycling glass.

Everyone needs to understand that the environmental benefits quantified below apply only when the glass is recycled back into glass. The much more common practice is to "recycle" glass into drainrock/aggregate substitute at construction sites. This "recycling" application represents a complete write-off of all the energy used to transform the sand into glass in the first place.

Is glass recycling a benefit to the environment or a feel-good exercise at considerable public expense?

Helen.

At 09:05 AM 04/14/2003 -0500, Reindl, John wrote:
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
product:

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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