Page 169 - Materials Chemistry, Second Edition

3.7 Illustration of the Inventory Phase by an Example 153

The modelling of the power plants was based on measured values, which
were made available to IFEU by operators of German power plants. This data
was supplemented by published values. 193) It was also intended to map a
regional state of the art of power plants.

3.7.3
Elaboration of a Differentiated System Flow Chart with Reference Flows

As a next step, the system flow chart can be provided based on a thorough analysis of
the product system and the structuring of the unit processes identified. Figures 3.30
and 3.31 show such differentiated system flow charts including the mass flows
calculated in the LCI and based on the reference flow data (see Table 3.8) for the
carton (Figure 3.30) and the PET system (Figure 3.31).
For the calculation of the LCI, the system flow chart must be refined to an
extent as to illustrate all considered unit processes and their interdependencies.
The degree of refinement depends on the data available (see Section 3.1.3.1);
Figures 3.32 and 3.33 show two examples as to how such refinements of system
flow chart may look.

3.7.4
Allocation

Since allocations are always based on conventions, the transparent description of
allocation rules is of great importance for the credibility and understanding of the
study (see Section 3.3). In this exemplary study the allocation rules are described
on process level, on system level, and with respect to waste treatment.

3.7.4.1 Definition of Allocation Rules on Process Level

Multi-output Processes Beverage raw carton and the necessary fibrous
materials are predominantly manufactured by integrated plants of the paper
industry. A product range of a set of paper or cardboard products, with
different fibre compositions, is usually covered. This and the networking of
the energy supply of all fibre lines make the allocation of energy consumption
and energy sources to individual product and fibre lines even more difficult.In
the available data records the appropriate allocations are accomplished by
the plant operators themselves. The data records made available are purely
inventory data. The original data and applied allocation procedures were not
available to the contractors.

193) Fritsche et al., 2001; Ecoinvent Centre, 2003.