Life cycle analysis and assessment
The concept of conducting a detailed examination of the life cycle of a product
or a process is a relatively recent one which emerged in response to increased
environmental awareness on the part of the general public, industry and
governments.
The immediate precursors of life cycle analysis and assessment (LCAs) were the
global modelling studies and energy audits of the late 1960s and early 1970s.
These attempted to assess the resource cost and environmental implications of
different patterns of human behaviour.
LCAs were an obvious extension, and became vital to support the development of
eco-labelling schemes which are operating or planned in a number of countries
around the world. In order for eco-labels to be granted to chosen products, the
awarding authority needs to be able to evaluate the manufacturing processes
involved, the energy consumption in manufacture and use, and the amount and
type of waste generated.
To accurately assess the burdens placed on the environment by the manufacture
of an item, the following of a procedure or the use of a certain process, two
main stages are involved. The first stage is the collection of data, and the
second is the interpretation of that data.
A number of different terms have been coined to describe the processes. One of
the first terms used was Life Cycle Analysis, but more recently two
terms have come to largely replace that one: Life Cycle Inventory (LCI)
and Life Cycle Assessment (LCA). These better reflect the different
stages of the process. Other terms such as Cradle to Grave Analysis,
Eco-balancing, and Material Flow Analysis are also used.
Whichever name is used to describe it, LCA is a potentially powerful tool which
can assist regulators to formulate environmental legislation, help
manufacturers analyse their processes and improve their products, and perhaps
enable consumers to make more informed choices. Like most tools, it must be
correctly used, however. A tendency for LCAs to be used to 'prove' the
superiority of one product over another has brought the concept into disrepute
in some areas.
What is a Life Cycle Analysis?
Taking as an example the case of a manufactured product, an LCA involves
making detailed measurements during the manufacture of the product, from the
mining of the raw materials used in its production and distribution, through to
its use, possible re-use or recycling, and its eventual disposal.
LCAs enable a manufacturer to quantify how much energy and raw materials are
used, and how much solid, liquid and gaseous waste is generated, at each stage
of the product's life.
Such a study would normally ignore second generation impacts, such as the
energy required to fire the bricks used to build the kilns used to manufacture
the raw material.
However, deciding which is the 'cradle' and which the 'grave' for
such studies has been one of the points of contention in the relatively new
science of LCAs, and in order for LCAs to have value there must be
standardisation of methodologies, and consensus as to where to set the limits.
Much of the focus worldwide to date has been on agreeing the methods and
boundaries to be used when making such analyses, and it seems that agreement
may have now been reached.
While carrying out an LCA is a lengthy and very detailed exercise, the data
collection stage is - in theory at least - relatively uncomplicated, provided
the boundary of the study has been clearly defined, the methodology is
rigorously applied, and reliable, high-quality data is available. Those of
course are fairly large provisos.
Interpretation
While such a record is helpful and informative, on its own it is not
sufficient. Having first compiled the detailed inventory, the next stage should
be to evaluate the findings.
This second stage - life cycle assessment - is more difficult, since it
requires interpretation of the data, and value judgements to be made.
A Life Cycle Inventory will reveal - for example - how many kilos of pulp, how
much electricity, and how many gallons of water, are involved in producing a
quantity of paper. Only by then assessing those statistics can a conclusion be
reached about the product's environmental impact overall. This includes the
necessity to make judgements based on the assembled figures, in order to assess
the likely significance of the various impacts.
Problems
It is here that many of the problems begin. Decisions, without scientific
basis, such as whether three tonnes of emitted sulphur is more or less harmful
than the emission of just a few pounds of a more toxic pollutant, are
necessarily subjective.
- How can one compare heavy energy demand with heavy water use: which
imposes greater environmental burden?
- How should the use of non-renewable mineral resources like oil or gas (the
ingredients of plastics) be compared with the production of softwoods for
paper?
- How should the combined impacts of the landfilling of wastes (air and
groundwater pollution, transport impacts etc) be compared with those produced
by the burning of wastes for energy production (predominantly emissions to
air)?
Some studies attempt to aggregate the various impacts into clearly defined
categories, for example, the possible impact on the ozone layer, or the
contribution to acid rain.
Others go still further and try to add the aggregated figures to arrive at a
single 'score' for the product or process being evaluated. It is doubtful
whether such simplification will be of general benefit.
Reliable methods for aggregating figures generated by LCA, and using them to
compare the life cycle impacts of different products, do not yet exist.
However, a great deal of work is currently being conducted on this aspect of
LCAs to arrive at a standardised method of interpreting the collected data.
Contradictions
Many LCAs have reached different and sometimes contradictory conclusions about
similar products.
Comparisons are rarely easy because of the different assumptions that are used,
for example in the case of food packaging, about the size and form of
container, the production and distribution system used, and the forms and type
of energy assumed.
To compare two items which are identically sized, identically distributed, and
recycled at the same rate is relatively simple, but even that requires
assumptions to be made. For example, whether deliveries were made in a 9-tonne
truck, or a larger one, whether it used diesel or petrol, and ran on congested
city centre roads where fuel efficiencies are lower, or on country roads or
motorways where fuel efficiencies might be better.
Comparisons of products which are dissimilar in most respects can only be made
by making even more judgements and assumptions.
Preserving the confidentiality of commercially-sensitive raw data without
reducing the credibility of LCAs is also a major problem. Another is the
understandable reluctance of companies to publish information which may
indicate that their own product is somehow inferior to that of a competitor. It
is not surprising that many of the studies which are published, and not simply
used internally, endorse the views of their sponsors.
Recycling
Recycling introduces a further real difficulty into the calculations. In the
case of materials like steel and aluminium which can technically be recycled an
indefinite number of times (with some melt losses), there is no longer a
'grave'. And in the case of pa-per, which can theoretically be reprocessed four
or five times before fibres are too short to have viable strength, should
calculations assume that it will be recycled four times, or not? What
return rates, for example, should be assumed for factory-refillable
containers?
For both refillable containers and materials sent for recycling, the transport
distance in each specific case is a major influence in the environmental
impacts associated with the process.
An LCA which concludes that recycling of low-value renewable materials in one
city is environmentally preferable may not hold good for a different, more
remote city where reprocessing facilities incur large transport impacts.
LCA in waste management
LCA has begun to be used to evaluate a city or region's future waste
management options. The LCA, or environmental assessment, covers the
environmental and resource impacts of alternative disposal processes, as well
as those other processes which are affected by disposal strategies such as
different types of collection schemes for recyclables, changed transport
patterns and so on.
The complexity of the task, and the number of assumptions which must be made,
is shown by the simplified diagram (above) showing some of the
different routes which waste might take, and some of the environmental impacts
incurred along the way. Those shown are far from exhaustive.
Why perform LCAs?
LCAs might be conducted by an industry sector to enable it to identify areas
where improvements can be made, in environmental terms. Alternatively the LCA
may be inten-ded to provide environmental data for the public or for
government. In recent years, a number of major companies have cited LCAs in
their marketing and advertising, to support claims that their products are
'environmentally friendly' or even 'environmentally superior' to
those of their rivals. Many of these claims have been successfully challenged
by environmental groups.
All products have some impact on the environment. Since some products use more
resources, cause more pollution or generate more waste than others, the aim is
to identify those which are most harmful.
Even for those products whose environmental burdens are relatively low, the LCA
should help to identify those stages in production processes and in use which
cause or have the potential to cause pollution, and those which have a heavy
material or energy demand.
Breaking down the manufacturing process into such fine detail can also be an
aid to identifying the use of scarce resources, showing where a more
sustainable product could be substituted.
Inconclusive
In most situations it is impossible to prove conclusively using LCAs that any
one product or any one process is better in general terms than any other, since
many parameters cannot be simplified to the degree necessary to reach such a
conclusion.
It seems likely that, in the case of manufactured goods, the most important
time for LCA information to be taken into consideration is at the design stage
of new products. Where LCA is used to evaluate procedures rather than products,
the information can help ensure appropriate choices are made.
Tool
Life Cycle Analysis must be used cautiously, and in the interpretation of the
inventory, care must be taken with subjective judgements.
When first conceived, it was predicted that LCA would enable definitive
judgements to be made. That misplaced belief has now been discredited. In
combination with the trend towards more open disclosure of environmental
information by companies, and the desire by consumers to be guided towards the
least harmful purchases, the LCA is a vital tool.
Source
World Resource Foundation
