cities in Norway so far, and was not included in the assessments of
the waste system. However, we included food waste sorting in the
comparative assessment of alternative scenarios performed subsequently.
All the source-separated recyclables were sent to Material
Recovery Facilities (MRFs). Paper was sorted in three fractions plus
residues, plastic in two fractions plus residues, and glass and metals
in three fractions without residues. All the waste fractions were
followed to their end destination, meaning that avoided environmental
impact from substitution of virgin materials was included.
Mixed waste was incinerated with heat recovery. The destination
of the incinerator residues, such as fly ash and bottom ash, was
not included; neither was metal extraction from the bottom ash.
Transportation was included in the model, but with fixed distances
of 20 km for transport from collection to the sorting facilities
or the incinerator, and of 100 km for transport from the
sorting facilities to the recycling centres. The collection vehicles
were assumed to be the same for all fractions. Similarly it was assumed
that the same type of truck was used for the long distance
transport of all fractions. This approximation was used in order to
make the results as generally applicable as possible. In any case,
transportation has been shown to have very little influence on
the performance of waste systems as long as the waste is not transported
for very long distances (Salhofer et al., 2007). The Nordic
electricity mix was used as the energy source for all processes taking
place in Norway. For processes carried out in Europe, such as
plastic recycling, an EU-mix was applied. For this we used an average
approach, assuming that changes in the waste system will not
affect the use of marginal energy in the countries involved. The approach
taken to energy in waste management LCAs is subject to
on-going discussion. While the ILCD Handbook (EU JRC, 2010) recommends
the use of average technology assumptions when
performing attributional LCA, and the use of marginal technology
assumptions for consequential LCA only, no recommendations
are widely agreed upon or followed (Bernstad et al., 2011; Fruergaard
et al., 2009). Contribution to this discussion is not included in
the scope of this study.