Re: [GRRN] Wood needed to make a ton of paper

Robert Kawaratani (
Sat, 27 Feb 1999 22:32:57 +0900

What type of paper and what type of wood are we assuming?

With a little help from the Encyclopedia Britannica cd-rom version:

1. Yield per ton dry weight of wood varies from 40 to 95% depending upon the
type of paper and wood.
2. A standard cord of wood is 128 cubic feet
3. A tree with a usable height of 40 feet and a circumference of 75 inches
will contain about one cord of wood.
4. Douglas Fir has an average density of 28 pounds per cubic feet (I assume
this is wet weight)
5. Dry weight is about 50% of wet weight

Newsprint and other mechanical pulp papers are high yield but require
greater inputs of electricity and fossil fuel while bleached copy paper and
toilet paper are at the low yield end but derive much of the energy for
producing the paper from the part of the wood that does not become paper.

Rougly speaking, a cord of wood based on the above assumptions would weigh
about 3600 pounds and assuming 40% yield, would produce about 720 pounds of
paper. 2.8 cords of wood would be required to produce that ton of paper.
Assuming 95% yield, 1.2 cords of wood would be required.

Note, I've made some simplifying assumptions such as ignoring bark which
would increase the amount of cords required per ton of paper. Also, in the
real world, many mills use a high fraction of lumber production residuals
(saw dust, etc.) in the production of paper so saying that it takes x
number of trees to make a ton of paper may not be a reasonable reflection of
the fiber balance for a given region or country. Cindy's 17 trees per ton of
paper might be reasonable if we're assuming the use of fast growing trees on
a 10 to 20 year crop cycle with harvesting at a smal size but would be not
be reasonable if we're assuming big trees like the ones in Helen's part of
Canada. However, big trees are usually harvested to produce lumber and the
resulting residuals are used for producing paper or other products.

You might address the question to the American Paper and Pulp Association
who could give you an answer based on field data as opposed to the back of
the envelope calculation I've performed above. Also, if there any mistakes
in my assumptions or logic, please let me know.