Large variations exist between paper grades in e.g. electricity
and heat use during production, fibre furnish, filler content and
recyclability. These parameters were found to influence energy
use over the life-cycle. The process energy needed for pulp and
paper production varies by more than a factor of 4 between
paper grades (8–34 GJ/t), due to variations in quality demands.
Differences in biomass input (0–32 GJ/t) and bio-energy output
(0–38 GJ/t) between grades are related to differences in virgin or
recovered fibre input. The impact of these differences depends further
on the modelling approach chosen (e.g. system boundaries
and allocation method). We found that grades with a high recycling
rate and/or low filler use, have the highest energy value at the
end-of-life (27–34 GJ/t). Even though the energy use of filler
production is smaller than that of fibre extraction, the life-cycle impact
of filler use is larger. Recycling was found to reduce life-cycle energy
intensity of all grades.