Page 218 - Materials Chemistry, Second Edition

206 E. Martínez Cámara et al.

• Freshwater aquatic ecotoxicity: this category is linked to the effects of emissions
into the air, soil, and water on freshwater ecosystems.
• Global warming (GWP100): this category is linked to the effects of greenhouse
gas emissions on human health and the environment.
• Human toxicity: this category is linked to exposure to toxic substances and their
effects on human health.
• Marine aquatic ecotoxicity: this category is linked to the effects of emissions on
marine ecosystems.
• Ozone layer depletion (ODP): this category is linked to the proportion of UV-B
radiation that reaches the surface of the Earth.
• Photochemical oxidation: this category is linked to reagents, mainly ozone,
whose appearance in the environment may have effects on human health and
ecosystems and may damage crops.
• Terrestrial ecotoxicity: this category is linked to the effects of emissions on
land-based ecosystems.

4 Analysis of Results and Future Trends

The results for the production of 1 kWh of electricity via wind power are shown in
Table 3, broken down into the various impact categories studied in the LCA and at
the characterization stage. The intention is to prevent the potential subjectivity
associated with other phases of the LCA and to facilitate the comparison of results
with other LCA in the fields of renewable and conventional energy sources.
For example, a comparison with the environmental impact associated with
electricity generation according to the Spanish energy mix for the year 2000 shows
that the figures obtained here are between 89 and 99 % lower, according to the
impact category considered. In the specific case of CO 2 emissions associated
directly with climate change (see the Global Warming category), the figure for 1
kWh of electricity generated via wind power is 98 % lower than the figure for the
Spanish energy mix.
Another interesting result can be provided by an examination of how long wind
turbines need to operate to offset their environmental impact from the time of their
manufacture through their operational lifetime and maintenance to their decom-
missioning, and the processing of the resulting waste. Taking as the starting point
for this analysis the fact that the energy generated by a wind turbine avoids the
need for an equivalent amount of energy to be produced via conventional sources,
another comparison with the Spanish energy mix can be made. The Spanish energy
mix is used for the purposes of comparison because the turbine studied is located
in Spain and the manufacturer is Spanish, but the results can be extrapolated to any
other country or location. Under this premise, the environmental impact caused by
the turbine is offset in between 53 and 784 days, depending on the impact category
considered.