compared to the total impact when applying the reference waste
composition. Positive percentage changes in the figure indicate
an improvement in impact.
The resource depletion impact category is an aggregation of the
use of fossil fuels, metals and renewable resources. Use of gravel,
sand, clay and limestone are not included. There are two important
processes for the resource depletion impact category in this study:
replacement of electricity production by the heat produced in the
incinerator and the substitution of virgin aluminium production.
The total resource depletion impact for the reference scenario is
negative, indicating a net saving in resources. As we can see in
Fig. 3, the scenarios with large amounts of waste with high heating
value going to the incinerator and increased weight of metals to
recycling will improve the system (paper low, plastic high, plastic
low, food low, glass high and metal high). With a ±15% change in
each component of the waste, the variation in outcome in Case 1
(constant sorting efficiency) is between 10% more and 3% less savings
than the reference scenario, and in Case 2 (varying sorting efficiency)
between 3% more and 4% less savings. In the Case 2
scenarios the quantities of waste going to the incinerator and the
source-separated metals are known, and changes in waste composition
is therefore of less importance to the total impact from the
system.
The global warming category aggregates the greenhouse gas
emissions into CO2-equivalents in a 100 year perspective. For the
reference scenario the total saved impact on global warming was