Page 274 - Materials Chemistry, Second Edition

L1644_C06.fm Page 247 Monday, October 20, 2003 12:06 PM

Finally, several technical elements are behind the methodology and its flowchart;
here only the main technical elements are outlined. The terminology is based on
Dale and English (1999). Due to the LCA part, a functional unit must be defined
and allocation models must be used in the LCI analysis. In the fate and exposure
analysis, fate and transport models (Gaussian, long-range transport, multimedia) are
applied. In the consequence analysis, dose–response and exposure–response func-
tions are employed. Laboratory exposure and animal tests are often the basis for
dose–response functions and epidemiological studies are the basis for expo-
sure–response functions. In order to make the weighting transparent, decision trees
have been established. Socioeconomic impact assessment is conducted with the
presented different methods to evaluate external costs. ERA uses individual risk- or
population risk based on the lifetime average dose. Accident simulation needs the
help of event and fault trees. Process simulation is, in principle, an engineering
model. Eco-efficiency could be calculated with the net present value of an expected
utility and the uncertainty analysis carried out with MC simulation.

6.8 CASE STUDY: ENVIRONMENTAL DAMAGE
ESTIMATIONS FOR THE WASTE INCINERATION
PROCESS CHAIN
The methodology has successfully been applied to the case study on the process
chain related to waste incineration, with interesting results. The information obtained
by the developed methodology might be crucial in the future for decisions on further
improvement of existing and new waste management systems. The presented algo-
rithm is applied to the life-cycle inventory of the electricity produced by the MSWI
of Tarragona, Spain.

6.8.1 GOAL AND SCOPE DEFINITION
Two operating situations of the MSWI are compared: the situation in 1996 and the
current situation after the installation of an advanced gas removal system (AGRS).
More data on the MSWI are presented in Chapter 1.
The function of the MSWI is to treat the household waste of the surroundings
of Tarragona. However, produced TJ of electricity is chosen as the functional unit,
as was done in the existing LCA study (see Chapter 2). The study comprises in its
system boundaries all the processes from municipal waste disposal in containers to
the landfill of the final waste (Figure 6.18). The midpoint-based weighting method
with single index, eco-indicator 95 (Goedkoop 1995) is used as LCIA method . The
method is based on the characterization factors presented by Heijungs et al. (1992)
and uses equal scores of distances to political targets (for more information see
Chapter 3).
For reasons of resource economy, in the dominance analysis only all processes
with a contribution greater than 10% will be selected for site-specific impact assess-
ment by a particular study. However, the remaining processes with more than 1%
should be evaluated by the transfer of available site-specific damage data or the use

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