paper can be made from a tree? Or, alternatively, how many trees are needed
to make a given amount of paper?
There is no simple answer to these questions, and all calculations can
be no better than ballpark estimates. Paper is made from a
mix of types of trees. Some are hardwood, some are softwood. In addition,
some are tall, some old, some wide, some young, some thin. Many of the
trees used to make paper are just chips and sawdust. So how
can one talk about a typical tree?
Conservatree has tracked down some ways to make ballpark estimates more
reliable than in the past. Heres some considerations to evaluate.
* Kinds of PaperPaper made in a groundwood process
(e.g. newsprint, telephone directories, base sheet for low-cost coated
magazine and catalog papers) uses trees about twice as efficiently as
paper made in the kraft or freesheet process (e.g.
office and printing papers, letterhead, business cards, copy paper, base
sheet for higher-quality coated magazine and catalog papers, advertising
papers, offset papers).
* Coated or Uncoated?The fiber in a coated paper (most often
used for magazines and catalogs, with a clay coating that may be glossy
or matte, or other finishes) may be only a little more than 50 percent
of the entire sheet, because the clay coating makes up so much of the
weight of the paper. As a ballpark estimate, you can use .64 as the fiber
estimate for coated papers compared to the entire weight of the sheet.
(Fiber estimate calculation by Alliance for Environmental Innovation.)
Claudia Thompson, in her book Recycled Papers: The Essential Guide (Cambridge,
MA: MIT Press, 1992), reports on an estimate calculated by Tom Soder,
then a graduate student in the Pulp and Paper Technology Program at the
University of Maine. He calculated that, based on a mixture of softwoods
and hardwoods 40 feet tall and six to eight inches in diameter, it would
take a rough average of 24 trees to produce a ton of printing and writing
paper, using the kraft chemical (freesheet) pulping process.
If it is assumed that the groundwood process is about twice as efficient
in using trees, then we can estimate that it takes about 12 trees to make
a ton of groundwood and newsprint. (The number will vary somewhat because
there often is more fiber in newsprint than in office paper, and there
are several different ways of making this type of paper.)
* One ton of uncoated virgin (non-recycled) printing and office paper
uses 24 trees.
* One ton of 100-percent virgin (non-recycled) newsprint uses 12 trees.
* A pallet of copier paper (20-lb. sheet weight, or 20#) contains
40 cartons and weighs 1 ton. Therefore, one carton (10 reams) of 100-percent
virgin copier paper uses .6 trees; one tree makes 16.67 reams of copy
paper or 8,333.3 sheets; one ream (500 sheets) uses six percent of a tree
(and those add up quickly!); one ton of coated, higher-end virgin magazine
paper (used for magazines like National Geographic and many others) uses
a little more than 15 trees (15.36); and one ton of coated, lower-end
virgin magazine paper (used for news magazines and most catalogs) uses
nearly eight trees (7.68).
How do you calculate how many trees are saved by using recycled paper?
* Multiply the number of trees needed to make a ton of the kind of paper
youre talking about (groundwood or freesheet).
* Then multiply by the percent recycled content in the paper.
For example, one ton (40 cartons) of 30 percent post-consumer content
copier paper saves 7.2 trees; one ton of 50 percent post-consumer content
copier paper saves 12 trees.
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