Page 128 - Materials Chemistry, Second Edition

112 3 Life Cycle Inventory Analysis

system expansion in Figure 3.20, the cut can be defined in the process ‘recycling’.
This hasasaconsequence:
1. In system A all loads related to waste disposal are avoided. (The recycled portion
is not assigned as waste.) There are no environmental impacts in connection
with waste disposal.
2. In system B all loads related to raw materials are avoided (the portion used
as secondary raw material has no loads owing to raw material extraction, no
resource consumption, etc.). These loads are completely allocated to system A.
3. The environmental loads for the recycling are allocated to the systems A and B
according to defined rules.

In the sense of a cycle economy 110) the rule is fair, it rewards both systems. The
avoidance of loads are different by nature, but do abide by logic:

• for A, recycling is actually waste avoidance;
• for B, the use of secondary raw material implies saving of primary raw material.
The behaviour is environmentally friendly if the special material supplied by A is
scarce and the upgrading process always included in the recycling step (Rec.), see
Figure 3.20, is not more demanding (energy use, emissions) than the production
of virgin raw material for B.
The greatest advantage of the rule is the ability to make an analysis based on the
knowledge of one system only (the one to be analysed). This can best be explained
by the following:
After use product A is collected and up-graded; the transport to a waste separation
plant is still part of A, as well as returned parts plus useless scraps, which can
be rated as waste of A. All further sub processes are allocated to System B
(transport, cleansing, upgrading if necessary, melting or granulation). This method
was successfully applied by Holley and co-workers in an inventory on beverage
packaging commissioned by UBA Berlin. 111) The secondary raw material is shifted
beyond the system boundary of A, gets temporarily stored and is shifted back from
there into system boundary B. Sorting and cleaning are divided between the two
systems as already indicated. An exact demarcation of systems has to be specified
for the individual case.
The application of the cut-off rule can be critical in cases of the carbon assessments
or determination of carbon footprints: the entire CO release from incineration,
2
for example, plastics, will be allocated to system B. At the same time the carbon
assessment of system A is no longer closed.
The resulting consequences of this simplification on the final results of the study
have to be examined in the context of the sensitivity analysis (see Chapter 5).

110) There is no really good English equivalent for the German word ‘Kreislaufwirtschaft’; a similar
concept is called Industrial ecology which stresses the similarity of an environmental friendly
business with natural ecosystems.
111) G¨ unther and Holley, 1995; Schmitz et al., 1995.