Paper recycling: a discussion of methodological approaches

Over the last decades increased use of waste paper as a source of fibre for the pulp and paper production process has meant that the industry has undergone significant changes in material and energy use. However, this means use of technologies that do not generate a significant amount of biomass for energy recovery, and thus requires that more energy is purchased by the industry. If waste paper is incinerated instead of repulped, energy purchases by society can be reduced, which will have a positive effect on CO2 emissions. In this article, we argue that an analysis of these effects requires a systems analytical approach including the different production lines, fibre flows and alternative uses of the fibre rather than a life cycle analysis with allocation methods. In the latter case, one often looks at just one production process and uses allocation methods for in- and outflow from or to other processes. We show that allocation methods sometimes used in life cycle analyses do not give a good approximation. Thus, it is recommended that allocation be avoided by, for example, expanding the system. If allocation cannot be avoided, the allocation should be based on the way in which the inputs and outputs are changed by quantitative changes in the products or functions delivered by the system. (C) 2000 Elsevier Science B.V. All rights reserved.