Page 254 - Materials Chemistry, Second Edition

244 G. A. da Silva et al.

methodological fullness. In any case, the considerations made by both studies lead
to important conclusions for life-cycle impacts of hydropower and also give some
typical range of values for environmental burdens.
A remarkable project was published on 2000 by the Scientific Certification
System (SCS) of California to the Washington Public Utility District. In this study,
a methodological approach based on LCA, called Life-Cycle Stressor Effect
Assessment was proposed as an alternative for environmental certification of
electricity enterprises (Carringnton 2000). The technique is basically composed by
definition and inventory steps, followed by a peculiar impact assessment, which
makes the difference from traditional LCA. In order to demonstrate the method, a
case study was conducted on Lake Cheelan Hydropower Plant, using some of the
definitions from the Vatenfall’s case (Vattenfall 1999).
In 2001, some attention was given to the theme of energy systems LCI’s, since
its relevance as source of environmental burdens had risen up. To foment the
discussion on this theme, the United States Environmental Protection Agency
(USEPA) promoted a workshop (USEPA 2001), where various experts debated
practical questions regarding electricity data for LCI. Based on different studies,
the experts concluded that each case demands a proper evaluation. However,
depending on the use to which the results of the study are provided, some generic
considerations could be made.
One last remarkable reference was published on 2002 in which some
researchers adopted LCA results obtained from literature, to make a comparison of
various electricity generation options (Gagnon et al. 2002). For each of the elec-
tricity sources, the authors compiled emission values, land use indexes, and the
energy payback ratios, presenting the results as typical values of environmental
performance for hydroelectric projects.

3 Methodology Recommendations for Hydropower
Life-Cycle Inventory Scope Definition Modeling

Even though each hydropower represents a different case, it is possible to con-
solidate some methodological considerations for hydropower LCI development,
based on the experience from literature studies, the Itaipu LCI, and also from two
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conferences on energy LCI s: the first one held in 1992 at Paris, France (OECD
1992); and, the second in 2001 at Cincinnati, United States (USEPA 2001).
The results of these conferences—that are not exclusive to hydropower, but for
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energy LCI s in general terms—revealed that besides the inherent complexity of
electricity generation systems, some specific factors bring additional difficulties to
develop electricity LCI. They are related to geographical extension; the large
seasonal variation of energy supply; significant differences of energy sources and
plant configurations (even when the method of generation is the same); rapid
technological evolution; and long-time scenarios (Krewitt 2001). These factors
lead LCI experts to establish general conventions.