Abstract
Environmental life cycle assessment (LCA) developed rapidly during the 1990s and has
reached a certain level of harmonisation and standardisation. LCA has mainly been
developed for analysing material products, but can also be applied to services, e.g. treatment
of a particular amount of solid waste. This paper discusses some methodological issues which
come into focus when LCAs are applied to solid waste management systems. The following
five issues are discussed. (1)
Upstream and downstream system boundaries
: where is the
‘cradle’ and where is the ‘grave’ in the analysed system? (2)
Open
-
loop recycling allocation
:
besides taking care of a certain amount of solid waste, many treatment processes also
provide additional functions, e.g. energy or materials which are recycled into other products.
Two important questions which arise are if an allocation between the different functions
should be made (and if so how), or if system boundaries should be expanded to include
several functions. (3)
Multi
-
input allocation
: in waste treatment processes, different materials
and products are usually mixed. In many applications there is a need to allocate environmen-
tal interventions from the treatment processes to the different input materials. The question
is how this should be done. (4)
Time
: emissions from landfills will continue for a long time.
An important issue to resolve is the length of time emissions from the landfill should be
considered. (5)
Life cycle impact assessment
: are there any aspects of solid waste systems (e.g.
the time horizon) that may require specific attention for the impact assessment element of an
LCA? Although the discussion centres around LCA it is expected that many of these issues