Microsoft Word - Environmental benefits of recycling 2010 update.doc

Table 41 Influence of the choice of material substitution for recycling in study n°2 (Shonfield, 2008)

Substitutes 100%

virgin plastic

Substitutes 20%

virgin plastic,

40% wood, 40%

concrete

Substitutes 100%

virgin plastic

Substitutes 20%

virgin plastic,

40% wood, 40%

concrete

Global warming potential (kg

eq CO 2 /ton) -620^439 -464^415

Depletion of abiotic

resources (kg eq Sb/ton)

-14 667 -2 547 -13 735 -2496

Energy demand (MJ/ton) -12 897 -7 363 -9 753 -1457

Recycling scenario 1 Recycling scenario 2

The choice of the displaced material and substitution ratio are therefore crucial but do not play a
role in the comparison across the studies analysed here since all the studies have assumed a
substitution of virgin plastic with a ratio of 1 in the case of closed-loop recycling (See Table 40), i.e.
recycled products replace same plastic products produced from virgin raw materials. In study no 1(BIOIS, 2006),
open-loop recycling is taken into account. The PET recycling scenario represents an aggregation of the three
main PET recycling channels: recycling into filling fibres (50%), recycling into PET resin (25%) and regeneration
(25%). However, when compared with the results of the other PET recycling scenarios (from studies 3, 6 and 7),
this different choice of substituted material does not appear to have a strong influence on the conclusions.

Energy valorisation

Energy recovery is mainly associated with incineration but is also often assumed for landfill for the cases
assuming biogas capture. Energy recovery can potentially offset the impacts resulting from the waste
treatment processes and is therefore a parameter that requires special attention.

First, in the case of incineration, the electric and/or thermal conversion efficiency of municipal
incinerators determines to what degree the need to produce electricity or heat from primary fuels is
avoided. The 2006 BAT standard for waste incineration gives efficiencies of 15-30% for incineration plants
generating electricity only. The efficiencies assumed in the selected studies stick to this range as shown in Table
42.

Table 42 Overview of the incinerator efficiencies assumed in the selected studies for plastics. The efficiency figures are based on gross calorific

values (GCV) or net calorific values (NCV). When it is not clear whether the figure is based on GCV or NCV a question mark is added.

Study

number

Energy produced

with incineration

Efficiency

5 electricity 15% (?)

6 electricity 17,8% (?)

2 electricity 23% (NCV)

4 electricity 25% (?)

1 electricity + heat 32% (GCV)

8 electricity + heat 65% (?)

3 heat 90% (NCV)

In study no 2 (Shonfield, 2008) a sensitivity analysis was conducted to test the potential influence of this
parameter. A comparison was conducted between a 30% and a 23% efficient plant. The results showed a 13%
decrease for the contribution to global warming when switching to 30% efficiency but this difference was not
sufficient to change the ranking of incineration compared to the other scenarios. The study therefore
concluded that this parameter is not expected to significantly influence the conclusions.

The second issue that arises is the choice of substituted power or heat which depends on the country
considered as illustrated in Table 43. This issue was also dealt with in study no 2 for incineration. Additional
scenarios for which power production from incineration substitutes for average production from the UK grid
(mainly based on natural gas (39.9%), coal (32.6%) and nuclear (19.1%)), and for production from a coal-fired