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
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