Page 209 - Materials Chemistry, Second Edition

EXERGY ANALYSIS AND ITS CONNECTION TO LIFE CYCLE ASSESSMENT 195

8.4.3 ExLCA Methodology and Approach
The frameworks of ExLCA (see Figure 8.3) and LCA are similar. The main steps
of ExLCA, and their similarities and differences from the main steps of LCA,
are as follows:

• The goal and scope definition step for ExLCA is identical with
that for LCA, which is described in section 8.2.1.
• The inventory analysis of ExLCA is more detailed than that for
LCA. Figure 8.3 shows the general flow diagram for ExLCA. A
complete flow diagram for the mass and energy flows involved
in each of the life cycle stages is required in ExLCA. Therefore, all
inputs and outputs must be identified and quantified. The mate-
rial and energy balances have to be closed, which is not always
the case in LCA (Hermann, 2006). Sometimes, a more simplified
black box approach is preferred for ExLCA, in which only the
inputs and outputs of the life cycle steps are taken into account.

Inputs for each stage Raw material acquisition Outputs for each stage

-► Intended products
Materials ► H
Energy ► Co-products and
energy
EXERGY -► -*· Emissions
Manufacturing
EXERGY
4

Use/reuse/maintenance

4

Recycling/waste
management

1 i
Figure 8.3 General framework for ExLCA, in the form of a flow diagram showing how the
inputs and outputs of matter, energy and exergy are considered for all steps in the life cycle of
a product or process.