quality demands. Biomass energy in is only related to paper grades
that (at least for some part) use virgin fibres (see Table 1). Corrugated
board and greyboard are produced from 100% recovered
fibres and therefore no biomass energy is allocated to these grades.
Only the grades that are (partly) produced from chemical pulp (i.e.
printing and writing paper and sanitary paper) show substantial
bio-energy output. For the other grades, the share of bio-energy
(from mechanical pulp or from recovered paper rejects) is so small
that it is hardly visible in Fig. 8. End-of-life energy indicates the
energy value of the paper grade at the end of its life-cycle. In our
study, two end-of-life options for fibres are modelled: (1) recycling
or (2)MSWincineration. If the fibre is recycled, the end-of-life
energy of the fibre is assumed to equal the feedstock energy needed
to produce the same amount of fibres from chemical pulp. If the
fibre is not recycled, it is assumed to be incinerated for energy.
From an energy point of view, recycling of the fibre is a more valuable
end-of-life option as the energy content of pulpwood replaced
is higher than the energy generated by MSW incineration. Not all
paper grades, however, consist solely of fibres. Insomepaper grades
the amount of fillers can be up to 50% (Table 3). Fillers do not contribute
to energy generation in MSW incineration. Moreover fillers
cannot be recycled in the process. Therefore, we have not allocated
an end-of-life energy value to fillers. In Fig. 8, it can be seen that
the grades with a high recycling rate and/or low filler use, have the
highest energy value at the end-of-life. Sanitary paper has a low
end-of-life energy value as it is not recycled nor incinerated. Printing
and writing paper has a high recycling rate (80%), however the
amount of fillers is high, which explains its lower end-of-life energy
value as compared to e.g. newsprint that has the same recycling
rate.