Page 274 - Materials Chemistry, Second Edition

264 G. A. da Silva et al.

5 Conclusion and Recommendations

The Itaipu LCI case study brought some information on scope definition and
inventory development that could be useful to future LCA practitioners. This topic
draws conclusions and presents some recommendations.
Regarding the proposed objective, it can be considered that the study achieved
the objective to develop a hydropower LCI representative of Brazilian conditions.
This result is useful as a basis for the extrapolation of the whole Brazilian grid,
following international practice. Nevertheless, the values presented must be taken
with care, given that each hydropower scheme is different from another. Moreover,
it should be noted that the evaluation of environmental and social impacts was not
conducted in this study, given the original objective developing a LCI.
After evaluating the results, it is possible to verify that hydropower LCI results
are very sensitive to the time horizon definition, which leads the authors to con-
clude that the huge contributions for environmental load of hydropower, derives
from the construction phase, confirming a general assumption. Also, it was pos-
sible to find that the most important sources of environmental burdens are as
follows: reservoir filling; steel life-cycle; cement life-cycle; and the operation of
civil work machines.
Regarding the results, it was possible to conclude that some level of cutoff
criteria should be applied, in order to ensure that environmental burdens that are
not representative are excluded from the LCI, avoiding misunderstandings.
Moreover, an extra care must be taken on data collection, in order to ensure quality
in terms of consistency and confidence between the different data sources.
A first conclusion in terms of the magnitude of the values refers to the relevance
of the time horizon and, more than this, the mathematical evidence of the con-
struction phase predominance on the life cycle, as a major source of environmental
load to the LCI. Another important conclusion on this topic is the verification of
the position of Itaipu results within the range of international values for hydro-
power life-cycle consumption and emissions as very favorable, which indicates,
with high probability, the inverse proportion between the magnitude of the
hydropower plant and the environmental load per unit of generated electricity.
In the absence of the impact analysis step of the LCA methodology, a dis-
cussion based on hot spots was performed in order to verify the contribution of
each part of the product system to the whole LCI, as already described.
The analysis—based on Itaipu results and in international experience—reveals
that the most important unit processes of the product system are the following:
reservoir filling, steel life cycle, cement life cycle and civil work machines
operation, besides the energy consumption on the building site operation, specif-
ically on concrete production. In future studies, these processes are not recom-
mended to be excluded, mainly when considering the electromechanical
equipment manufacture, maintenance and substitution within 100 years of
operation.