Page 82 - Materials Chemistry, Second Edition

64 LIFE CYCLE ASSESSMENT HANDBOOK

The extensive databases available within LCA software tools can greatly
streamline the time and effort required to conduct an LCA. However, wide-
spread use of the software and public databases brings with it a new set of
responsibilities and issues for consideration by the practitioner. When con-
structing LCA models with these tools, it is still the responsibility of the prac-
titioner to carefully review the data sets and make adjustments as necessary to
ensure consistency and relevance for the systems that are being modeled. The
practitioner also needs to be aware of underlying differences that may exist in
different data sets that are available. Examples include:

• Differences in energy content of inputs from nature. Some data-
bases use the lower heating value of materials, while others use
higher heating value. It is also important for the practitioner to
ensure that energy flows are linked to data sets corresponding to
the corresponding form or stage of material input (e.g., uranium
has different energy values at different stages of processing).
• Differences in methodology. Data sets may have embedded allo-
cations that may not be consistent with the allocation approach
used for other processes or materials in the system being mod-
eled. Depending on the level of detail available in the data set, it
may or may not be possible to apply a different allocation method.
• Differences in naming conventions. When working within LCA
software, before adding a new substance to a data set, the practi-
tioner should check to make sure that the substance is not already
listed in the database under a different name. Chemical Abstracts
Service (CAS) registry numbers are often the most effective way
to search for substances that may go by multiple names. If new
flows are added, the practitioner must make sure that the added
flows are also added to the appropriate impact categories and
methods within the software tool. Otherwise, the flow may show
up in the inventory but not in the relevant impact results.
• Differences in emissions lists for the same process. For the same
process, data sets from different databases or representing differ-
ent countries may have variations in emissions lists. It is impor-
tant to check whether these variations are associated with actual
process differences or differences in completeness of reporting.
The absence of an emission may not mean that emissions of that
substance are zero but rather that the emission was not reported
in the data sources used to develop the data set. Differences in
completeness can be misleading when they result in apparent
differences in impacts for systems that use similar processes and
materials.
• Regional differences
• Differences in technology. As noted previously, technologies
and technology mixes may differ in various regions of the world.
For example, there are three basic electrolysis technologies for