*4.2. Social Perception*

In addition to technological, economic, and legal issues, social perception is an important aspect of development, evolution, and expansion of wind energy. A review of the literature in this area is included in [24]. The authors point out that despite the widespread support for the idea of renewable energy, local acceptance is at a very low level. This is a significant barrier to the development of this branch of energy. The article analyzes specific case studies in various regions of Europe described in the literature. Comparative and both qualitative and quantitative analyses were carried out. It was indicated that an important factor in the development of renewable energy is gaining social trust. It is necessary to implement information strategies based on high quality technical, economic, legal, social, environmental and health data.

#### *4.3. Impact on the Natural Environment*

The impact of wind energy on the ecosystem is subject to constant research and monitoring. One problem is the noise generated by wind turbines. This issue concerns not only the acoustic waves generated in the air but also the underwater noise produced by offshore wind farms. The article [25] discusses the most important problems related to this issue. Based on the collected literature, the results of measurements made in various locations were reviewed. This allowed for the analysis and comparison of noise parameters generated by offshore turbines. The noise level was analyzed depending on the type and number of turbines, size, wind velocity, and distance from the noise source. Based on the survey of measurements, it has been found that the level of low frequency underwater noise produced by turbines is approximately 10 to 20 dB lower than that generated by other facilities such as large cargo ships. While the noise level is relatively high near the turbines themselves, it decreases quickly with distance. The size of the turbines or the velocity of the wind have less influence here. Currently, turbine noise has a significant environmental impact in areas where the levels of other sources are low. However, the constant development of offshore wind energy will result in the intensification of underwater noise and the necessity to take action to reduce the noise impact on the environment.

One of the very important issues related to wind energy is the impact on the natural environment. One of the aspects of this topic is the mortality of flying fauna, i.e., birds and bats. This issue is studied and monitored in many areas of the world. The article [26] reviews this subject in Latin America. This is particularly interesting because most of the research is focused on Europe and North America. The authors of the article draw attention to the lack of reviews in Latin America so far and are trying to fill this gap. It is important because Latin America is potentially a region of rapid and intensive development of wind energy in the coming years. The research conducted so far in this area indicates that sparrows constitute the largest number of victims among the birds, while there are no endangered species. However, one endangered species was reported among bats. The available amount of information in this area is limited; therefore, it is difficult to make an unambiguous and complete assessment of this phenomenon. However, it is necessary to develop and intensify activities related to reducing the possibility of collisions between animals and wind turbines. It would be helpful to use the experience from other areas of the world where research in this field is more advanced.

#### *4.4. Economic Issues and Indicators*

The departure from traditional methods of electricity production based on the combustion of fossil resources has become a civilization necessity. Therefore, various methods of generating energy are being developed. It becomes imperative to compare and economically evaluate various energy sources. Levelized costs of electricity are a widely used indicator for comparing the costs of energy production. Along with the development of wind power and other modern energy technologies, it was necessary to adapt the methods of determining this indicator to the properties of these technologies. The article [27] reviews these methods as applied to renewable energy. Economic considerations related to investments, operations, performance, and risks are included here. The uncertainty in determining economic indicators was analyzed. On the basis of the literature review, the authors of the work [27] indicate the problems that should be taken into account when determining economic indicators for renewable energy sources. These include variable efficiency, location and seasonal conditions, cooperation with the grid, and renewable energy policies. The authors point out the need to take into account the uncertainty of data and parameters in the modeling of economic indicators.

An important exploitation indicator is also life cycle assessments. A systematic review of the methods for determining this indicator, based on the literature, is included in [28]. The review covers all major methods of electricity generation, including those based on the combustion of fossil fuels, nuclear energy, and renewable energy. The authors indicate

that despite the development of methods for determining life cycle assessments, there are still many unresolved problems that require further development. This applies to the improvement of data processing methods, standardization, and the wide use of results by decision makers.
