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It is widely recognised that the energy sector has a negative influence on the environment. All the processes involved in the whole energy chain (raw materials procurement, conversion to electricity, and its use) generate environmental burdens that affect the atmosphere, the water, the soil and living organisms. Environmental burdens can be defined as everything producing an impact on the public, the environment, or the ecosystems. The most important burdens derived from the production and uses of energy are: greenhouse gases; particles and other pollutants released into the atmosphere; liquid wastes discharges on water and/or soil; and solid wastes.
However, not all the energy sources have the same negative environmental effects or natural resources depletion capability. Fossil fuel energies exhaust natural resources and are mostly responsible for environmental impacts. On the contrary, renewable energies in general, and wind energy in particular, produce few environmental impacts, significantly lower than those produced by conventional energies.
Ecosystems are extremely complex entities including all living organisms in an area (biotic factors) together with its physical environment (abiotic factors) that function as a unit. Thus, the specific impact of a precise substance on the various components of the ecosystem is particularly difficult to assess, as all potential relationships should be addressed. This is the role of impact assessments: the identification and quantification of the effects produced by pollutants or burdens on different elements of the ecosystem. It is important because only those impacts that can be quantified can be compared and reduced.
Results from an environmental impact assessment could be used to reduce the environmental impacts in energy systems cycles. Also, those results should allow the design of more sustainable energy technologies, and provide clear and consistent data in order to define more environmentally respectful national and international policies. For all these reasons, the use of suitable methodologies capable of quantifying in a clear and comparable way the environmental impacts becomes essential.
This chapter describes the LCA methodology for the emissions and environmental impacts assessment and, based on relevant European studies, shows the emissions and environmental impacts derived from the electricity production from onshore and offshore wind farms throughout the whole life cycle. Also, the avoided emissions and environmental impacts occurred by wind electricity compared to the other fossil electricity generation technologies have been displayed.
Life Cycle Assessment (LCA) is an objective process to evaluate the environmental burdens associated with a product, process, or activity by identifying energy and materials used and wastes released to the environment, and to evaluate and implement opportunities to affect environmental improvements.
The assessment includes the entire life cycle of the product, process or activity, encompassing, extracting and processing raw materials; manufacturing, transportation and distribution; use, re-use, maintenance; recycling, and final disposal (the so called "cradle to grave" concept).
According to the ISO 14040 and 14044 standards, a Life Cycle Assessment is carried out in four phases:
Figure 1.1. Conceptual framework on LCA, Source: ISO 14040
In the phase dealing with the "Goal and scope definition", the aim, the breadth and the depth of the study are established.
The "Inventory analysis" (also called Life Cycle Inventory - LCI), is the phase of life cycle assessment involving the compilation and quantification of inputs and outputs, for a given product system throughout its life cycle. LCI establishes demarcation between what is included in the product system and what is excluded. In LCI, each product/material/service should be followed until it has been translated into elementary flows (emissions, natural resource extractions, land use…).
The third phase "Life Cycle Impact Assessment" aims to understand and evaluate the magnitude and significance of the potential environmental impacts of a product system. This phase is further divided into four steps. The first two steps are termed "Classification and characterisation" and impact potentials are calculated based on the LCI results. The next steps are "Normalisation and weighting", but these are both voluntary according to the ISO standard. Normalisation provides a basis for comparing different types of environmental impact categories (all impacts get the same unit). Weighting implies assigning a weighting factor to each impact category depending on the relative importance.
The two first steps (classification and characterisation) are quantitative steps based on scientific knowledge of the relevant environmental processes. On the contrary, normalisation and valuation are not technical, scientific or objective processes, but may be assisted by applying scientifically-based analytical techniques.
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