Page 109 - Materials Chemistry, Second Edition

Life Cycle Assessment: Principles, Practice and Prospects
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would extend around this process alone. Assessment of water impacts would result in all the
water used in the butter manufacture being allocated to a unit of butter production. In this
example, wastewater is reused in a downstream process (because the butter process does not
‘deplete’ the water severely) and so the system boundary can be expanded to include the
mushroom cultivation which is using the wastewater from the butter manufacture. The
expanded system boundary allows the total water consumed to be allocated to both co-prod-
ucts (butter and mushrooms), and this more accurately reflects the actual consumption of the
water resource.
Neither of these options deals with the location-specific issues of water use and nutrient
flows. While no firm proposals have been put forward, differentiating water use within differ-
ent archetypical climates would be an advance on the straight addition of water use. The
impacts then of water extraction in water-limited environments could be assessed differently
to water use in non water-limited environments. A measure could therefore consider water use
in terms of the catchment area required to yield the water used. This would link water use to
water availability; however, this method would also require some default assumptions about
water use from larger regions or from unknown origins.

8.3 Assessing the life cycle impacts of synthetic water systems
Drought in large parts of populated Australia has led to scrutiny and introspection of water
supply and consumption systems and their purposes. As water users and suppliers seek to plan
within the physical limits of existing water resources, efforts have been made to seek alterna-
tive supply options and reduce demand. As a result, a myriad of water saving options have been
developed, each theoretically capable of partly addressing water shortage, all other things
remaining equal. With a wide range of options available, choosing the most appropriate options
has proved difficult. Without selection criteria, it is difficult to decide which system to apply to
the ‘water problem’. LCA and Life Cycle Costing (LCC) have emerged as useful techniques to
aid the choice.
In addressing water ‘scarcity’, an underlying theme is to make water supplies more ‘sustain-
able’. Scarcity and sustainability are, of course, relative and related terms when used in this
context. Solutions to water scarcity are typically presented as technically feasible initiatives
selected purely on economic grounds, in the same way that many other capital investment
projects are assessed, although many water practitioners, perhaps aware of the tight connec-
tions between water supply systems and the natural water cycle, have sought to incorporate
sustainability into the decision-making framework. LCA has been chosen by some practition-
ers as a proxy for environmental sustainability, and in some cases this has led to a reassessment
of the technical feasibility of the water option being considered.
The natural ‘water system’ is essentially cyclic and driven by gravity and solar power, yet
there are numerous options for interfering with the habit of water molecules as they make their
way around the various natural flows and stock points. Hence, the technology options for sup-
plying and treating water vary and LCAs of these also vary. In essence, however, the analysis of
a water supply or treatment system typically involves developing an inventory of impacts asso-
ciated with the construction and disposal of the water system infrastructure, and an inventory
of impacts associated with operation over its life. In combination, the infrastructure impact
and the operational impact represent the total life cycle impact of the water system. Flow of
water through the environment makes it difficult to understand completely the operational
impacts. For this reason, many water LCAs attempt to capture extended consequential effects
through expanded systems boundaries. It is therefore common for an LCA of a synthetic water
system to include the downstream impacts on water treatment and stormwater systems, and in
some cases supply systems.

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