Chemistry Reference
In-Depth Information
emissions of global warming gases and world
resource depletion can be calculated relatively
easily; however, other impacts, such as acidification
or human toxicity, are more difficult to determine on
the global level so that normalisation still is not a
reliable method for comparing the different envi-
ronmental impacts from a system.
Valuation
is the final and most subjective step of
impact assessment, in which the relative significance
of different impacts is weighted so that they can be
compared among themselves. As a result, different
environmental impacts are reduced to a single envi-
ronmental impact function,
EI
, as a measure of envi-
ronmental performance. This can be represented by
Equation 5.3:
Further details on LCA methodology can be found
in Refs 10 and 11-14.
3 The Applications of LCA
As an environmental management tool, LCA has
several objectives:
• To provide as complete a picture as possible of the
interactions of an activity with the environment
• To identify major environmental impacts and the
life-cycle stages or 'hot spots' contributing to these
impacts
• To compare environmental impacts of alternative
product, processes or activities
• To contribute to the understanding of the overall
and interdependent nature of the environmental
consequences of human activities
• To provide decision-makers with information
on the environmental effects of these activities
and identify opportunities for environmental
improvements.
K
Â
1
EI
=
w
kk
(5.3)
k
=
where
w
k
is the relative importance of impact
E
k
.
A number of techniques have been suggested for
use in valuation. They are based mainly on express-
ing preferences by decision-makers, by 'experts' or
by the public. Some of these methods include multi-
attribute utility theory, analytical hierarchy process,
impact analysis matrix, cost-benefit analysis and
contingent valuation [25]. However, because of a
number of problems and difficulties associated with
using these techniques, there is no consensus at
present on how to aggregate the environmental
impacts into a single environmental impact function.
These objectives have governed the use of LCA in
both corporate and public decision-making arenas,
which to date have included:
• Assessment and comparison of consumer products
• Support of environmental management systems
• Process selection and system optimisation
• Environmental reporting and marketing
• Policy formulation at national and international
levels
Improvement assessment
In the SETAC methodology, Improvement Assess-
ment is the final phase of the LCA methodology and
is aimed at identifying the possibilities for improving
the environmental performance of the system. This
phase can be carried out before an LCA study is com-
pleted because the opportunities for improvements
can be detected at an early stage of carrying out the
study. The redesign of the product or a process as a
result of the Improvement Assessment phase is not
part of the LCA—it is one of its applications.
In the ISO methodology this phase is known as
Interpretation [14]. The Interpretation phase also is
aimed at improvements and innovations, but in
addition it covers the following steps: identification
of major burdens and impacts, identification of stages
in the life-cycle that contribute the most to these
impacts, evaluation of these findings, sensitivity
analysis and final recommendations.
The body of literature on LCA applications is vast and
its review is outside the scope of this chapter. Instead,
some typical examples are chosen here to illustrate
the usefulness of LCA as a tool for identifying
environmentally more sustainable products and
processes.
3.1 Product-oriented LCA
Historically, most of the LCA literature and case
studies have been product-oriented [9,21,25-34].
The early LCA studies, originating in the 1980s,
compared different consumer products, including
beverage packaging, washing machines and deter-
gents. The scope of the studies and number of prod-
ucts analysed expanded in the early 1990s and to
date include LCA studies of products in the follow-
ing industrial sectors: chemical [35-37], gas [38,39],
