The progress of the life cycle assessment (LCA) started in the 1980s, according to Davidsson et al. (2012), and became increasingly common during the 1990s when scientific publications began to reach wider audiences. As the concept of LCA evolved, many different methods and guidelines came on stream. There are recent developments which are very well described by (Finnveden et al., 2009; Guinée et al., 2011). According to Guinée (2001), LCA can be defined as “the compilation and evaluation of the inputs, outputs and potential environmental impact of a product system throughout the life cycle”. It can be said that life cycle assessments generally follow the same four basic steps: goals and scope, life cycle inventory, impact assessment, and interpretation.
There are several definitions of life cycle analysis (LCA). Al-Behadili and El-Osta (2015) defined it as the medium of measuring environmental factors that impact on a product's life cycle; from inception to decommissioning (i.e., from raw material
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extraction to materials processing, manufacture, distribution, use, repair and maintenance, and disposal). They stated that it is generally accepted that wind energy is one of the cleanest and most sustainable forms of energy generation, yet does create minuscule environmental pollution throughout the phases of its life cycle, such as during manufacturing and dismantling of the wind turbines.
In terms of life cycle inventory (LCI), entries and outputs of the whole life cycle are estimated in accordance with the chosen system boundaries and methods. There are several different ways to do this, and choices in methodology can have a large impact on final results. Ekvall and Weidema (2004) suggested two broad categories; attribution LCI, and consequential LCI. In terms of attribution LCI, this is described as the physical inflows that are associated with the environmental impact in and out of the life cycle system limits. By contrast, consequential LCI is a system which generates information about the outcome of actions made by describing how the physical flows which are relevant to environmental impact will change with certain variables in the life cycle. It is necessary at this stage to make the point that there is not always a clear practical distinction between attribution and consequential LCI. Following that is life cycle impact assessment (LCIA), where the results from the inventory are translated into environmentally relevant information (Baumann and Tillman, 2004). Martínez et al. (2009) have compared several methods to perform an LCIA. At times, attempts are being made to express the impact on a base and common scale through weighting or further evaluating the results of LCIA. This can never be based solely on purely objective factors, as subjective values always must be introduced (Baumann and Tillman, 2004). For this reason, LCA may not necessarily be a method that fulfils the standards of strict natural science. This should be taken with caution and handled with regards to the interpretation of the results.
Tremeac and Meunier (2009) analysed the life cycle of 4.5MW and 250W wind turbines. In the study, they compared two wind turbines of 4.5MW and 250W in order to estimate the environmental impact. All phases of the life cycle were analysed; which included manufacturing, transports, installation, maintenance, disassembly, and disposal. They found that to provide an optimum environmental solution, significant factors include:
1) High efficiency turbines should be implemented in a high wind speed region 2) Transportation components should not spend too much energy
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3) Recycling during decommissioning should be performed correctly
The researchers stated that there are two aspects which are considered important and are to be taken into consideration in regards to the deployment of wind turbines and their management:
- Component transportation must be as limited as possible. Factories should be distributed on the earth’s surface in correlation with wind farms to be built. When, nevertheless, large distance transportation is necessary, boat or train should be preferred to truck.
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Recycling during decommissioning is an important step, and not to be underestimated, in order to achieve good environmental impact figures.
Martínez et al. (2009) studied a life cycle assessment of a multi-megawatt wind turbine. They investigated the emissions produced while the wind turbine was in operation; furthermore, the contamination and environmental impact resulting from their manufacture and the future dismantling of the turbines at the end of their working life was studied. They particularly looked at the application of the ISO 14040 standard in order to carry out an LCA study quantifying the overall impact of a wind turbine and each of its components. The researchers studied the wind turbine from inception to decommission with regard to the manufacture of its key components (through the incorporation of cut-off criteria), transportation to the wind farm, subsequent installation, start-up, maintenance, and final dismantling and stripping down into waste materials and their treatment. It was found that the cement foundation is the component which most significantly affects the environment because of the impact on the inorganic respiration (IR) category, which is one of the categories from the Eco-Indicators guideline.
In a similar study by Martínez et al. (2010), which investigated the four phases of life cycle analysis (LCA) of a system: maintenance, manufacturing, dismantling, and recycling using the Eco-indicator 99 life cycle analysis (LCA) method, examined the significant options available in the development of the wind farm. From the derived outcomes, it is reasonable to assert that it is necessary to more precisely analyse and define the average of major corrections that a turbine may encounter throughout its 20 year life, as, without a doubt, the decisions taken at the maintenance phase of the turbine have a significant effect on the outcome of the LCA. Another problem that
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significantly affects the final results of the LCA study of wind turbine megawatts in question are is the issue of recycling and reusing components and materials. A clear example is the impact of materials such as fibreglass blades for wind power when not recycled but sent directly to landfill.
Life cycle impact assessment (LCIA) has been established to estimate potential environmental burdens, according to (Klöpffer and Grahl, 2014). Although it is not statistical and mathematical in nature, it represents what would be referred to as a ‘balance of probabilities’. It is important to note that LCA is not essentially geared to estimate the impact of extremely unlikely, catastrophic events, such as the effect of an earthquake on a costal nuclear station. The authors begin Part 4 by reviewing mandatory and optional elements of LCIA as per the ISO standards. They then define mid-point and damage categories.
Al-Behadili and El-Osta (2015) analysed and evaluated life cycle analysis (LCA) by examining the impact of the commissioning of a wind farm in Dernah, east of Libya, by considering the whole life cycle of the project. They concluded that the energy payback period is just under 6 months (5.7 months), and the corresponding pay back ratio is given as 42.1, which is found to substantiate results found in similar studies. It is found that the electricity generated by one wind turbine is given as 1.65 MW (TWT 1.65/82). This wind farm is expected to diffuse approximately 10.42, 0.02713, 0.03823, 0.0001474, 0.0001065, 0.0003469 and 0.0112237 grams per kWh CO2, SO2, NOx, N2O, CH4, NMVOC and CO respectively. This study found that wind energy produces the lowest CO2 emission per kWh of electricity (10.4 g/kWh) generated in comparison to non-renewable sources such as fossil fuel. It was found that when there is recycling of the wind turbine material the specific emission of CO2 is 4.65 g/kWh of energy generated. Furthermore, the amount of fuel savings is given as 85,700 m3 per year or 79,013,800 kg fuel per year, which is now translated to ($2.8 million/year £2.11million/year /0.85 million KD/year)(which is more than (($66 million/ £50 million/ 20 KD million) over the lifetime of the wind farm) if the local subsidised price of heavy fuel oil is considered. The savings could reach a value as high as ($63,404,570/year/ £47,883,131/year /19,156,423KD)(($1.3 million/£0.98million /0.39million KD) over the entire lifetime of the wind farm) if the international prices of heavy fuel oil are considered.
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