Page 271 - Materials Chemistry, Second Edition

Hydropower Life-Cycle Inventories 261

Fig. 3 Process contributions to the most important environmental burdens (Ribeiro and Silva
2010)

generated on the whole period. As mentioned before, this parameter was defined as
100 years. Nevertheless, some simulations were developed changing the time
horizon to 60 years, and afterwards to 200 years.
The results of these tests not only had confirmed the high influence of the time
horizon over the environmental profile but also indicated that if the LCI results do
not vary so much, it was because the greatest part of the environmental loads
comes from a life-cycle phase that is not time-dependent. The obvious conclusion
was that the dam construction occurs on this phase.

4.5.4 Comments regarding the magnitude of the LCI results

A screening on the LCI results showed that the most part of the environmental
burdens would not be significant, if a cutoff criteria had been applied. This pro-
cedure was not adopted on the study due to its objective and resources restrictions,
but it is recommended on LCAs which intends to use this LCI as an electricity
database.
A comparison with LCIs of other electric generation options pointed out that
hydropower seems to present a better environmental performance than others, such
as natural gas thermal plants, but one should consider that there are plenty of social