Page 258 - Materials Chemistry, Second Edition

248 G. A. da Silva et al.

For many authors (OECD 1992; Krewitt 2001; Frischknetcht 2001), the life
cycles of construction materials and civil works, as well as emissions of particulate
matter from earthworks, and GHG emissions from flooded areas, should not be
disregarded. So a complete data collection must be conducted in these life-cycles
processes.
Other important aspect of hydropower modeling for LCI purposes is the allo-
cation procedure. Even though in many cases it could be observed a multiplicity of
usages for the hydropower reservoir—e.g., recreation, fishing, etc.—it is recom-
mended not to adopt any allocation procedure for this case (Curran 2001).
An important alert regarding environmental impacts associated with land
occupation and transformation in hydropower systems should be done. Notwith-
standing social impacts of building a dam and the environmental impacts of
flooding the same area, only primary flows of mass and energy tend to be con-
sidered for this class of LCI. In order to establish an indicator of these social and
environmental impacts, it is suggested to include an accounting of areas with
potential of occupation and transformation. However, the authors are fully aware
that this strategy does not fulfill the need for a broad environmental impact study,
which should evaluate the burdens of the hydropower generation such as people
displacement, ecosystem modifications, agriculturally productive land loss, and so
on. This approach will certainly be one of the main challenges for the LCA
community in the near future.

3.4 Data Sources

International experience reveals that the data collection for LCI of hydropower can
be divided in two steps. The first one is performed in order to quantify the con-
sumptions and emissions—i.e., inputs and outputs flows—associated with building
and maintenance of the power plant. In this case, it is usual to include the amounts
of cement, sand, gravel, iron and steel, water, copper, diesel oil, plus all the
transport operations, and civil work machines employed either in its construction
or operation. This part of the data collection is usually conducted based on primary
data, i.e., collecting information directly from the constructor of the dam and other
manufacturers and suppliers.
In the second step, the life cycle of those materials, products and services is
estimated. In the cases in which there are no databases available, or even if the
existing information is not representative, complementary data should be collected
in technical literature, and a treatment process of the same information must be
performed in order to provide consistency and representativeness for the whole
LCI. Access to this information may be difficult or even impossible and even with
all these precautions one should take care to avoid incorporating uncertainties to
the study.
In all the studies consulted in this literature review, primary data were used on
the power plant demand for material and energy—e.g., consumptions of cement,