Chemistry Reference
In-Depth Information
'. . . a compilation and evaluation of the inputs,
outputs and the potential environmental impacts
of a product system throughout its life cycle'.
Economy
Compared with other environmental manage-
ment tools, LCA is probably not much different in
what it is trying to achieve, i.e. to identify opportu-
nities for reducing the environmental impacts of a
system. However, the main difference lies in the way
the system boundaries are defined: in conventional
environmental systems analysis, such as environ-
mental impact assessment, the system boundary is
drawn around a manufacturing site or a plant,
whereas in LCA the boundary is set to encompass
the following life-cycle stages:
LCA
*
SA*
SA*
Materials,
energy
Goods and
services
Wastes
Society
Environment
• Extraction and processing of raw materials
• Manufacturing
• Transportation and distribution
• Use, reuse and maintenance
• Recycling
• Final disposal
Fig. 5.1
Positioning LCA within the context of sustainable
development (SA
=
sustainable activity).
As illustrated in Fig. 5.2, the life-cycle of a product
starts from the extraction and processing of raw
materials, which then are transported to the manu-
facturing site to produce a product. The product
then is transported to the user and at the end of its
useful life is either recycled or is disposed of in a
landfill. In all of these stages, materials and energy
are consumed and wastes and emissions generated.
By taking into account the whole life-cycle of an
activity along the supply chain, LCA enables the
identification of the most significant impacts and
stages in the life-cycle that need to be targeted for
improvements. Such a holistic approach avoids shift-
ing of the environmental burdens from one stage to
another, as often may be the case in conventional
environmental systems analysis where the system
boundary is drawn too narrowly.
Both SETAC [10] and ISO [11-14] define four
phases within the LCA methodological framework,
with small differences between the two methodolo-
gies, as outlined in Table 5.1. Although it is expected
that the ISO methodology eventually will supersede
the SETAC methodology, the latter still remains
more widely used by LCA practitioners. Thus, the
following discussion refers to the SETAC methodol-
ogy with an explanation of the differences between
the two methodologies, where appropriate.
2.1 Methodological framework
Two major international bodies have been involved
in developing the LCA methodology: the Society for
Environmental Toxicology and Chemistry (SETAC)
and the International Standardization Organization
(ISO). Much of the pioneering work was done by
SETAC in the first half of the 1990s, and further
methodological developments by ISO have followed
on from that work. This is probably the reason why
the two methodologies have converged and the dif-
ferences between them are in detail only. The early
SETAC definition of LCA, which is still widely
quoted, reads [9,10]:
'Life Cycle Assessment is a process to evaluate the
environmental burdens associated with a product,
process, or activity by identifying and quantifying
energy and materials used and wastes released to
the environment; to assess the impact of those
energy and material uses and releases to the envi-
ronment; and to identify and evaluate opportuni-
ties to effect environmental improvements. The
assessment includes the entire life cycle of the
product, process or activity.'
A much more succinct but otherwise similar ISO
definition defines LCA as [11]:
