3.0 Results of the comparative analysis of the selected publications
3.1 Introduction to the methodology used for results comparison
Throughout this section, results are presented by material for the four indicators previously listed that are
considered to be of major concern. Other indicators, i.e. acidification, photochemical oxidation, eutrophication
and toxicity, were also looked at but in a less detailed manner.
For comparability reasons, the end-of-life options have been compared to each other within one study. The
system boundaries and assumptions are too different between studies to be able to calculate differences between
alternatives across studies. For example, if study no X analyses two types of biopolymers, e.g. PLA and Mater-Bi,
the various end-of-life alternatives for PLA are grouped under Case X[PLA] and the ones for Mater-Bi under Case
X[MB]. If two end-of-life alternatives are compared for PLA and Mater-Bi, the study is then composed of two
cases containing two scenarios each. A detailed description of each case and the results of each scenario are
provided in the relevant Appendix.
In the graphs used to compare the various scenarios, the results are presented in terms of relative difference
between the options being compared. For example, if composting is used as the reference, the relative difference
calculation is as follows:
(Impact from end-of-life option A – Impact from composting)/ Impact from compostingA negative value on the scale means that the results for composting cause more environmental impact than the
other end-of-life option. On the graphs, the size of the bubble is proportional to the number of scenarios coming
up with a value within the same range as another as illustrated in the figure below. The scenarios coming up with
values under -150% or above +150% are placed on the same line at both ends. This type of graph allows for
some global trends to be discerned but does not enable the associated scenarios to be identified. The detailed
results for the different scenarios are presented in tables.
2111(^41)
1
‐175%
‐150%
‐125%
‐100%
‐75%
‐50%
‐25%
0%
25%
50%
75%
100%
125%
150%
175%
Relative difference with recycling according
to the number of cases
%
<‐ 150
%
150%
<‐150%
recycling
preferred to
alternative
alternative
preferred to
recycling
Water consumption
Incineration
with energy
recovery
Landfill Pyrolysis
Impact Indicator
4cases indicate
that recycling is at
least 150% better
than incineration
2 cases indicate
that landfill is 75%
to 100% better
than recycling
Alternative used as a
reference
1 case indicates that
recycling is 75% to
100% better than
pyrolysis
1 case indicates
that recycling is
125% to 150%
better than
inicneration
Figure 2 Guidance for reading the graphs used for the comparative analysis