Wood in Our Future: The Role of Life-Cycle Analysis Proceedings of a Symposium (1997) / Chapter Skim
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LIFE-CYCLE THINKING FOR WOOD AND PAPER PRODUCTS
LIFE-CYCLE THINKING FOR WOOD AND PAPER PRODUCTS
Pages 11-16
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From page 11... ...
There was relatively little energy recovery from the incineration of paper, so this, too, posed few perceived problems. By treating wood products in this way, the carbon source did not enter into the analysis, and the fate of the carbon after disposal was similarly excluded from the system.
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From page 12... ...
They ranged from the simple sentiment that "omitting makes the numbers lower," through the more sophisticated "the energy is free and should not be included," to the pseudoeconomic "wood is not a commercial fuel and so should not be treated as though it were one." The problem with omitting wood feedstock from calculations is that it leads to the absurd conclusion that some processing steps are net producers of energy. For example, if paper in municipal waste is incinerated and energy is recovered, then the incinerator is a net producer of energy from an energy-free feed.
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From page 13... ...
Paper and board substrates can therefore be regarded as carbohydrates that contain 45 percent carbon by weight. THE CARBON CYCLE A tree absorbs atmospheric CO2, water, and sunlight for conversion to the materials we call wood and bark.
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From page 14... ...
Feedstock energy must be included in energy calculations. It is, however, important to keep its contribution to the overall total energy separate from other contributions in the same way that electrical energy is kept separate from the contribution of fossil fuels.
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From page 15... ...
By including wood feedstock in calculations for integrated pulp and paper plants, total energy might not be reduced compared with nonintegrated plants; indeed, it might actually be increased because of the lower conversion efficiencies of woodfueled boilers. The critical factor is not total energy but the amount of fossil fuel energy that is put into the system.
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From page 16... ...
SUMMARY When dealing with wood products in life-cycle inventories, there are six points to apprehend: analysis. · Carbon dioxide absorption during tree growing should be included in the · Carbon dioxide emissions from wood product incineration must be included in the analysis.
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