Microsoft Word - Environmental benefits of recycling 2010 update.doc

11

31

22

12 11

11

2

22

‐175%

‐150%

‐125%

‐100%

‐75%

‐50%

‐25%

0%

25%

50%

75%

100%

125%

150%

175%

Relative difference with composting according

to the number of cases

>150

%

<‐ 150

%

>150%

<‐150%

composting

preferred to

alternative

alternative

preferred to

composting

Climate change

Recycling Incineration

with energy

recovery

Incineration

without energy

recovery

Landfill Anaerobic

digestion

Study n°2

Study n°2

Study n°4

Figure 32 Influence of the assumptions regarding energy recovery on the composting performances in studies n°2 and 4

Avoided production/use of material

Some end-of-life alternatives lead to the production of secondary products that bring credits to the
system. For example, in studies 2, 3 and 4, the compost is used as soil conditioner and plant growing medium
instead of peat or inorganic fertilisers as shown in Table 64. On the contrary, in the composting scenarios in
studies 1, 6 and 7, there is no product substitution assumed for the compost produced. For anaerobic digestion,
assessed in studies 3 and 7, the digestate that is produced can also be valorised. This is the case for study no 3
in which the digestate is assumed to replace both mineral fertilisers and peat. However, there is no clear
evidence of the influence of these parameters on the results for anaerobic digestion and composting. It is instead
the assumptions around the degradation rates or energy recovery that predominate.

Table 64 Substituted products for composting and anaerobic digestion for biopolymers

Study

number

Substituted material by

compost

Substituted material by

digestate

1 No substitution /

2 Inorganic fertilisers /

3 mineral fertilisers and peat mineral fertilisers and peat

4 peat /

5 //

6 No substitution /

7 No substitution No substitution

The good performance of recycling is also explained by this parameter. For instance, in scenario 2 [MB] for
recycling, the relative difference between recycling and composting exceeds 9000% in favour of recycling for
climate change. This can be explained by the fact that in this scenario, the recycling of the biopolymer (Mater-Bi)
avoids some production of virgin Mater-Bi which is responsible for high greenhouse gases emissions.