Volume 2 wind energy 2 16 – environmental social benefits impacts of wind power

Volume 2 wind energy 2 16 – environmental social benefits impacts of wind power Volume 2 wind energy 2 16 – environmental social benefits impacts of wind power Volume 2 wind energy 2 16 – environmental social benefits impacts of wind power Volume 2 wind energy 2 16 – environmental social benefits impacts of wind power Volume 2 wind energy 2 16 – environmental social benefits impacts of wind power

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E Kondili and JK Kaldellis, Technological Education Institute of Piraeus, Athens, Greece

2.16.1 Introduction – Scope and Objectives

2.16.2 Main Environmental Benefits of Wind Power

2.16.2.1 General Considerations

2.16.2.2 Avoided Air Pollution – Reduction of CO2 Emissions

2.16.2.3 Reduction of Water Consumption

2.16.3 Main Social Benefits of Wind Power

2.16.3.1 Fossil Fuel Saving/Substitution

2.16.3.2 Regional Development – New Activities

2.16.3.3 Employment Opportunities and Job Positions in the Wind Power Sector

2.16.4 Environmental Behavior of Wind Energy

2.16.5 Methods and Tools for Environmental Impact Assessment

2.16.6 Noise Impact

2.16.6.1 Qualitative and Quantitative Consideration of Noise Impact

2.16.6.2 Research and Development Relevant to Wind Turbine Noise

2.16.7 Wind Turbines’ Visual Impact and Aesthetics

2.16.7.1 General Considerations on Visual Impact and Aesthetics

2.16.7.2 Shadow Flickering

2.16.8 Impacts in Fauna and Flora and Microclimate

2.16.8.1 Impacts in Flora and Fauna

2.16.8.2 Impacts on the Microclimate

2.16.9 Other Environmental Impacts

2.16.9.1 Interference of a Wind Turbine with Electromagnetic Communication Systems

2.16.9.2 Traffic – Transportation and Access

2.16.9.3 Archaeology and Cultural Heritage

2.16.9.4 Health and Safety

2.16.10 Offshore Environmental Impacts

2.16.10.1 Offshore Noise Impact

2.16.10.2 Construction and Decommissioning Noise

2.16.10.8 Effects of Offshore Wind Energy on the Microclimate

2.16.11 Mitigation Measures – Conclusions

2.16.11.1 The Importance of Wind Farm Siting

2.16.11.2 Mitigation through Technology

2.16.12 Social Acceptability of Wind Power Projects

2.16.12.2 Case Studies for Public Attitude Analysis

2.16.13 The Public Attitude Toward Offshore Wind Parks

2.16.14 Future Trends in Wind Parks’ Social and Environmental Impacts Assessment

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504 Environmental-Social Benefits/Impacts of Wind Power

2.16.1 Introduction – Scope and Objectives

Wind energy is characterized as a clean and environmentally friendly technology, and this is one of the main benefits that makes

it such an attractive and promising energy supply solution For the completeness of wind energy analysis it is considered very critical

to describe concisely other wind energy effects, such as the social and environmental impacts that may incur from the corresponding projects implementation, in parallel to its technological and/or financial implications To that effect, the present chapter deals with

fuels imports reduction, creation of new job positions, and regional development

On the other hand, there are some environmental concerns resulting from wind power plants, such as noise, visual impacts, and

a possible disturbance of wildlife In some cases, these concerns are extensive and affect negatively or even hinder the implementation of the corresponding projects The environmental impact assessment (EIA) of these projects identifies in detail the environmental impacts and suggests their mitigation measures, facilitating in that way their acceptance by local societies Another very interesting issue that is of high priority when examining wind power projects is their social acceptance and the public attitude toward them These issues are also discussed in this chapter

Nowadays, it is a common belief that wind energy has a key role to play in combating climate change by reducing CO2 emissions from power generation Generally, it does not pollute the air-like thermal power plants that rely on combustion of (carbon containing) fossil fuels such as oil, coal, or natural gas Wind turbines do not produce atmospheric emissions that cause acid rain

or greenhouse gases Wind power plants may be built in villages, in remote areas, thus benefiting the economy in the region, employment, and the development of parallel satellite activities It is definitely considered as a green power technology

In the rest of the chapter the main impacts (positive and negative) of wind energy projects on people in surrounding areas are identified and described Offshore wind power plants are a special interesting category with distinct and, in many cases, different environmental impacts, and, therefore, they are described in a separate section

2.16.2 Main Environmental Benefits of Wind Power

Wind energy is one of the cleanest and most environmentally friendly energy sources It has a long-term positive impact on the environment by reducing the threat posed by climate change It emits no greenhouse gases or air pollutants or particles that are carcinogenic and affect human health severely The development of wind power plants creates employment opportunities and new job positions during equipment construction, installation, and operation of the new power plants Also, since wind power plants are located in remote areas, new industries and satellite activities are emerging and regional development is enhanced in order to support the construction and the operation of the new plant during its whole life cycle At the local level, wind energy may also have positive effects on biodiversity and offer an opportunity to practice ecological restoration both onshore and offshore, such as the creation of new vegetation and animal habitats, improved fish stocks, and other marine life

Table 1 highlights the main environmental and social benefits of wind energy

2.16.2.2 Avoided Air Pollution – Reduction of CO2 Emissions

All electricity generation schemes have a carbon footprint This means that at some points of their construction and operation, CO2 and other greenhouse gases are emitted A carbon footprint is the total amount of CO2 and other greenhouse gases emitted over a

Fossil fuel technologies have the largest carbon footprints since power production is achieved through combustion processes Nonfossil fuel technologies such as renewable energy sources (RES) are often referred as low carbon or carbon

Table 1 Main social and environmental benefits of wind power

Avoided air pollution – reduction of CO2 emissions Reduction of water consumption

Fossil fuels saving/substitution Positive effects on the microclimate of the area New job positions – employment opportunities Regional development

Development and support of domestic construction industry and various satellite activities

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emissions arise in other phases of their life cycle, for example, during raw materials extraction, equipment construction, plant installation, maintenance, and decommissioning, however originating from the embedded energy In any case, their very low carbon footprint compared to the conventional energy sources has been the main advantage for their current development and advancement

Coal burning power plants have the largest footprint of all electricity generation systems Conventional coal combustion

Nearly all the emissions related to wind energy refer to the embedded energy of the various wind park components and occur during the manufacturing and construction phase, arising mainly from the production of steel for the tower of the wind turbine, concrete for the foundations, and materials for the rotor blades These all account for 98% of the total life cycle emissions The emissions generated during the operation of wind turbines arise from routine maintenance inspection trips Onshore wind turbines are accessed by vehicles, while offshore turbines are maintained using special vessels and helicopters The carbon footprint of offshore versus onshore wind energy generation is marginally greater since it requires larger foundations

Figures 1 and 2 indicate the CO2 footprint for various different electricity generation sources As it can be seen from these figures,

2.16.2.3 Reduction of Water Consumption

In an increasingly water-stressed world, water consumption is a very important issue Taking into account the imperative ability considerations, the minimization of the water consumption in power production could be one of the most significant criteria for a process and technology selection in case there are alternative solutions available

sustain-Conventional power plants use large amounts of water for the condensing portion of the thermodynamic cycle For coal power plants, water is also used to clean and process fuel The amount of water used can be millions of liters per day By reducing the usage

of water, it can be preserved and used for other purposes

Table 2 Emissions of pollutants per kWh of produced electricity – benefits of wind power versus coal and natural gas [2]

Emissions per kWh of produced electricity Wind power benefits

wind wind wind coal Lignite NGCC Coal Lignite NGCC

wind Nuclear

Solar

PV

Solar thermal

Biomass CHP

Biomass CHP Carbon dioxide,

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100

90

80

grass (miscanthus) direct combustion

Graph's Data Max Graph's Data Min

range for UK wave energy converters

Figure 1 Carbon footprint (bounds) of various power production technologies [2]

Figure 2 Carbon footprint of various conventional and renewable power production technologies [3]

Figure 3 shows the full-cycle water consumption per unit of electricity for fossil fuels and nuclear power plants, respectively, utilizing once-through (OT), closed-loop (CL), and dry cooling technologies Combined cycle gas turbines (CCGT) have the lowest consumption rates of the three plant types examined, while nuclear power plants and plants with advanced coal technology and carbon capture and sequestration (CCS) present the highest Integrated gasification combined cycle (IGCC) is somewhere in between these technologies as far as water consumption is concerned The averages used are the simple mean of the low and high estimates [6]

exploitation

Renewable sources for electricity have very diverse water consumption issues Wind and solar photovoltaic (PV) use practically no water, while concentrating solar power (CSP) uses steam turbines and therefore has water consumption patterns comparable to or higher than conventional power plants The different ones are geothermal and hydropower, as they both use very large quantities of water, but have definitional issues that make it difficult to compare directly with other sources of electricity

In any case, from all the above it is apparent that wind energy in its life cycle uses very little or no water and it is very advantageous in that respect compared to other power generation technologies

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Min Max

3 2.5

2 1.5

1 0.5

Min

A v er age Max

Steam Turbine (CL)

Steam Turbine (Dry) IGCC

PC (Pulv

eriz

ed Coal)

Adv Coal with CCS

CCGT (O

T)CCGT (CL)CCGT (Dr

y)

Figure 3 Water consumption in electricity generation using different cooling technologies, including water consumed during fuel extraction and processing [6]

Figure 4 Water consumption from renewable energy sources [6]

2.16.3 Main Social Benefits of Wind Power

2.16.3.1 Fossil Fuel Saving/Substitution

One of the main social benefits of the exploitation of wind energy is its contribution in minimizing the operation of thermal power stations; hence, the operation of wind parks substitutes coal and oil-fired or natural gas-based thermal power stations More

Ewind

u

chemical energy of the fuel to electricity

More specifically, the operation of wind-based power stations first of all reduces the energy imports (oil, natural gas, coal, etc.) for almost all energy-importing industrialized countries contributing to annual exchange loss reduction Note that the imported energy exchange loss is strongly dependent on the unstable and continuous increasing prices of oil and natural gas in the international market In order to avoid any misleading conclusions, the money spent to import the necessary equipment (e.g., wind turbines) is less than the macroeconomic cost resulting from the corresponding fossil fuel imports during two successive years, while the service period of the wind power stations exceeds 20 years

Besides, the exploitation of wind energy improves energy supply security, since it minimizes the significant hidden cost of fossil

energy contributes in reducing the exploitation of fossil fuel reserves, prolonging, in this way, their operational life

2.16.3.2 Regional Development – New Activities

As with most business ventures, wind energy projects create jobs and new activities in the specific areas where they are installed and, more widely, in the whole country where they are implemented

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Repair/O&M 11%

Engineering 3%

Wind Turbine Manufacture 37%

Other Component Manufacture 22%

Developers 16%

Utility 9%

OthersConsultancy

R&D 1%

Figure 5 Direct employment by type of company in the wind energy sector [7]

In general, the main activities associated with the wind energy include the manufacturing of the turbine and all the other necessary equipment, the construction and installation of the plant, its operation and maintenance activities, and other parallel activities such as engineering, consultancy, education, distribution network, and utilities

More specifically, the activities and the relevant employment fields related to wind power plants (Figure 5) include the following:

• Raw materials processing (e.g., metallic, synthetic materials)

• Wind turbine manufacturers

• Major subcomponent manufacturers (metallic and electrical machinery)

• Companies generating and distributing electricity (utilities)

• Wind energy promoters (consultancy and engineering)

• Research and development (R&D) activities in aerodynamics, computational fluid dynamics, and materials

• Engineering companies for the design and development of the wind power plants

• Technicians and specialized personnel for the operation and maintenance of the plant

• Wind energy measurement and forecasting (developers)

• Instrumentation manufacturing and trade (manufacturing other components)

• EIA professionals (consultancy and engineering)

• Education and training services (others)

• Land and site development (developers)

• Activities related to the permission acquirement (consultancy and engineering)

• Specialized financial services (others)

• Legal, health, and safety services (others)

All the above create direct or indirect employment Most of these activities are closely related to the place where the plant is to be installed and this is the reason that regional development is achieved Nevertheless, for the completeness of the subject, it should be mentioned at this point that some job positions may be lost because of the development of a wind power plant replacing partially

or completely a local thermal power station

2.16.3.3 Employment Opportunities and Job Positions in the Wind Power Sector

Wind energy projects generate many new activities and certainly have positive effects on employment [7] The implementation of these projects creates a significant number of specialized jobs (over 104 000 in 2008) [8], especially at a time when other energy sectors are shrinking Wind turbine manufacturers, including major subcontractors (components manufacturers), are responsible

qualified personnel, such as project managers, engineers, and operation and maintenance technicians These job positions need a series of educational, mobility, and dissemination measures to be put into practice

A survey has been carried out to investigate the number of employees working directly in the wind energy sector [8] The survey has been carried out by means of a questionnaire dispatched to around 1100 organizations from 30 countries (the 27 EU member states plus Croatia, Norway, and Turkey) It went to all European Wind Energy Association members and the members of the EU-27 national wind energy associations Supplementary information in order to fill the gaps has been provided from the following:

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Figure 6 Direct jobs in the wind energy sector in the EU member states [7]

• Reviewing the annual reports and websites of the main wind energy companies, notably large wind turbines manufacturers, component manufacturers, developers, and utilities

• Using the results of the studies coming from the countries where the main wind turbine manufacturers are based, that is, Denmark, Germany, and Spain

• Assessing the data compiled by the national wind energy associations

The results of the survey indicate that wind energy companies in the EU currently employ around 104 000 people The growth experienced (226%) between 2003 and 2007 is consistent with the evolution of the installed capacity in Europe (276%)

In this context, a significant proportion of direct wind energy employment is based in three countries, Denmark, Germany, and Spain, whose combined installed capacity also adds up to 70% of the total in the EU (Figure 6) The situation in the eastern European member states varies, with Poland being in a leading position Wind energy employment in these countries will probably rise significantly in the

Nevertheless, the sector is less concentrated now than it was in 2003 when these three countries (Denmark, Germany, and Spain) accounted for 89% of employment and 84% of EU installed capacity This is due to the opening of manufacturing and operation centers in emerging markets and to the local nature of many wind-related activities, such as promotion, operations and maintenance, engineering, and legal services [9]

By type of company, wind turbine and component manufacturers (Figure 5) account for most of the jobs (59%) Within these categories, companies tend to be bigger and thus employ more people

Employment from the wind energy sector makes up around 7.3% of the total amount of people working in the electricity-generating sector and it should be noted that wind energy currently meets 3.7% of EU electricity demand This shows that wind energy is more labor-intensive than the other electricity-generating technologies

Finally, there is a well-documented trend of energy employment decline in Europe, particularly marked in the coal sector For instance, British coal production and employment have dropped significantly, from 229 000 workers in 1981 to 5500 in 2006 In Germany, it is estimated that jobs in the sector will drop from 265 000 in 1991 to less than 80 000 in 2020 In EU countries, more than 150 000 utility and gas industry jobs disappeared in the second half of the 1990s and it is estimated that another 200 000 jobs will be lost during the first half of the twenty-first century The outcomes set out in the previous paragraphs demonstrate that job losses in the European energy sector are independent of renewable energy deployment and that the renewable energy sector is, in fact, helping to mitigate these negative effects in the power sector

The increase in wind energy installations has led to a multiplication of job offers in all the subsectors, especially in manufacturing and development Actually, one may state that the average new job creation in the European market is approximately two employees per new MW installed, with values exceeding the seven new jobs per MW installed in some specific countries (see also Figure 7) Concerning the qualifications and the profile of the field employees, a shortage in those positions that requires a high degree of expertise and responsibility is identified The positions that are most difficult to fill in are those related to operations and maintenance, project management, and aerodynamics engineering The standardization of qualifications and a better information system could help to ease the situation and facilitate the transfer of workers toward the areas where they are needed

The conclusion is that wind energy represents an attractive source of employment in Europe Since a number of activities (construction, operation and maintenance, legal, and environmental studies) are best dealt with at local level, there will always be a positive correlation between the location of the wind farm and the number of jobs it creates

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yIreland ItalyNether

landsPolandPortugal SpainSw

eden UK

Figure 7 Employment opportunities in the wind energy sector in EU countries per MW of installed capacity [3]

2.16.4 Environmental Behavior of Wind Energy

Although wind energy is possibly the most environmental compatible form of energy, there are some environmental impacts that should be considered when studying the installation of a new wind power plant Most of the environmental impacts can be avoided

or minimized (by careful planning and siting), mitigated, or compensated In fact, wind farm developers are required to undertake

The main environmental impacts of a wind farm are shown in Table 4 In the general case the most serious environmental impacts of wind power plants are related to noise, aesthetics, and their potential effects in the wildlife of the specific geographical area

The European legislation associated with the identification and mitigation of environmental impacts of any development activity is the consolidated version of the Council Directive 97/11/EC [10]

When looking at a potentially suitable site, a study analyzing all relevant environmental and ecological factors should be carried out These form the basis of an EIA that must be submitted alongside a planning application, demonstrating that any potential environmental impact will be mitigated and that the impacts of development are outweighed by the benefits

The various impacts are classified according to the environmental parameters they refer to In addition, the impacts are very

the equipment manufacturing and the plant construction stages The operation of a project has no serious environmental impacts Furthermore, in the general case, the impacts may be characterized as temporary or permanent, reversible or irreversible, and of low

or high significance

A general table of contents of an EIA study as dictated by the current legislation (May 2011) is shown in Figure 8

More specifically, for a wind power plant the EIA must examine the following environmental parameters:

• Noise Noise is considered as one of the most significant environmental impacts of wind power on nearby regions

• Visual impacts – aesthetics It is also a very significant issue related to wind power plants

• Impacts on wildlife Effects on local and emigrating bird life, flora, and fauna

• Landscape and land use The possible need to change the land use and the effects of the wind park on the landscape

• Surface and ground water To assess any likely impacts on water quantity and quality within both the development area and surrounding countryside and ensure these are minimized

• Archaeology – cultural sites Both national and local archaeological groups are consulted to establish if proposed sites are likely to have any significant impacts on heritage sites or archaeological remains

Table 4 Main environmental impacts of wind power plants

Noise Effect on the electromagnetic waves Visual impacts – aesthetics Archaeology and cultural heritage Landscape and land use Transportation issues

Impacts on the wildlife, flora, and fauna Health and safety

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Table of Contents of a typical EIA

(Detailed project description including type of the project, project location, technical specifications, size of

the project/capacity, infrastructure required, networks, technology to be used, utilities required, project

plan, project budget)

CHAPTER 2: PROJECT LOCATION

2.1 Natural Environment (Soil, Topography, Water Resources, Flora, Fauna, Climate)

2.2 Human Environment (Population, Land use, Distances from inhabited areas, Cultural/Historical places,

Other characteristics of the area)

CHAPTER 3: EXISTING ENVIRONMENTAL SITUATION

3.1 Existing pollution sources

3.2 Assessment of environmental pollution before the project

CHAPTER 4: ENVIRONMENTAL PARAMETERS OF THE PROJECT – ENVIRONMENTAL IMPACTS

� Other location, other size, other technology/process, etc

CHAPTER 6: POLLUTION PREVENTION – MITIGATION OF THE ENVIRONMENTAL IMPACTS

CHAPTER 7: CONCLUSIONS

REFERENCES – LITERATURE – ANNEXES

Figure 8 Structure and contents of an Environmental Impact Assessment Study according to the Directive 97/11/EC

2.16.5 Methods and Tools for Environmental Impact Assessment

EIA is a tool for decision-makers to take into account the possible effects of a proposed project on the environment and is also a process for collecting the data related to a project design and project location Various methods and tools have been developed (Figure 9) in order to identify and predict the environmental impacts of a project In general, the tools may be classified into quantitative and qualitative The qualitative tools include the following:

• Checklists

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Scoping and Impact

Evaluation Techniques Identification

Matrices ModelingConsultations &

Questionnaires

Expert Opinion Carrying CapacityChecklists

Analysis Spatial Analysis

Figure 9 Methods and tools in the environmental impact assessment

Knowledge-based systems, referred to as expert systems, and different computer-based systems are an emerging technology in information processing and are becoming increasingly useful tools in different applications areas including EIA studies

The checklists provide a systematic way of ensuring that all likely events resulting from a project are considered Information is presented in a tabular format It is a systematic method; therefore, standard checklists for similar projects may be developed They are very valuable since they present in a simple table all the potential impacts of a project The main drawback is that cause and effect relationships are not specified

Matrices are a more complex form a checklist They link the causes and effects for the specific characteristics of a project and a mark is assigned in each cell indicating how much each project characteristic contributes to a certain impact Therefore, matrices can

be used also quantitatively and can evaluate impacts to some degree They provide a good visual summary of impacts In the matrices, since quantitative information is included, the impacts may be ranked to assist in evaluation

As an example of wind power project checklists, Table 5 shows the environmental impacts of the construction phase of a wind park, while Table 6 shows the corresponding impacts of the operational phase [11] In addition, Table 7 is an example of

Table 5 Checklist for the environmental impacts of the construction phase of a wind park [11]

Environmental parameter Environmental impact Impact characteristics

Earth – soil Soil compaction Permanent, medium significance, certain, negative

Soil fracture, soils admixing Temporary, medium significance, certain, negative Soil erosion Temporary, medium significance, very likely, negative Overlay of soil Permanent, high significance, certain, negative Soil contamination and productivity Temporary, low significance, likely, negative Slope damage Permanent, medium significance, less likely, negative Change of local topography Permanent, medium significance, certain, negative Air quality Air emissions production Temporary, high significance, certain, negative

Dust generation Temporary, low significance, certain, negative Odors generation Temporary, low significance, certain, negative Water resources Groundwater contamination Temporary, low significance, less likely, negative

Surface waters contamination Temporary, low significance, likely, negative Water consumption Temporary, low significance, certain, negative Land use Change of existing land use Permanent, medium significance, certain, negative Flora and fauna Vegetation disturbance Temporary, low significance, very likely, negative

Animals and avian mortality Temporary, low significance, likely, negative Harassment of wildlife and habitats damage Temporary, low significance, very likely, negative Energy Electrical energy consumption Temporary, low significance, certain, negative

Fuels consumption increase Temporary, medium significance, certain, negative Noise Mechanical noise Temporary, high significance, certain, negative Cultural resources Damage of significant archaeological resources Permanent, medium significance, very likely, negative Visual resources Landscape aesthetics disruption/improvement Temporary, low significance, very likely, negative Natural resources Increase of local resources’ exploitation rate Temporary, low significance, very likely, negative Health and safety Accidents Temporary, high significance, very likely, negative

Health issues Temporary, medium significance, less likely, negative Transportation Increase of local traffic Temporary, low significance, very likely, negative

Extension (improvement) of existing transportation Permanent, medium significance, certain, negative/

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Table 6 Checklist for the environmental impacts of the operation phase of a wind park [11]

Environmental parameter Environmental impact Impact characteristics

Earth – soil Soil compaction Permanent, medium significance, certain, negative

Soil erosion Permanent, medium significance, likely, negative Air quality Air emissions production Permanent, low significance, certain, negative

Dust generation Permanent, low significance, certain, negative Odors generation Permanent, low significance, certain, negative Air emissions reduction Permanent, high significance, certain, positive Flora and fauna Harassment of wildlife Permanent, low significance, less likely, negative

Avian mortality Permanent, medium significance, likely, negative Animals and birds emigration Permanent, low significance, likely, negative Energy Fuels consumption reduction Permanent, high significance, certain, positive

Electricity generation Permanent, high significance, certain, positive Noise Mechanical noise Permanent, low significance, certain, negative

Aerodynamic noise Permanent, high significance, certain, negative Visual resources Landscape aesthetics disruption Permanent, high significance, very likely, negative

Landscape aesthetics improvement Permanent, high significance, very likely, positive Shadow flickering Permanent, low significance, very likely, negative Flashing Permanent, medium significance, very likely,

negative Health and safety Accidents Permanent, medium significance, very likely,

negative Health issues (air emissions) Permanent, high significance, certain, positive Health issues (radiation) Permanent, low significance, less likely, positive Agricultural crops and livestock Disturbance of agricultural activities Permanent, low significance, likely, negative

Disturbance of livestock activities Permanent, low significance, likely, negative Local society, economy, and Arising of objections toward the wind park’s Permanent, low significance, likely, negative

Electricity security of supply Permanent, medium significance, certain, positive Local grid power quality issues Permanent, high significance, certain, negative Employment offer Permanent, low significance, certain, positive Reduction of the electricity tariffs Permanent, medium significance, likely, positive Promotion and development of local area Permanent, medium significance, very likely,

positive

(low) to 5 (high) [11]

2.16.6 Noise Impact

2.16.6.1 Qualitative and Quantitative Consideration of Noise Impact

One of the most noticeable impacts a wind turbine places upon the environment is noise emission In some cases the impact of noise emission has the potential (mainly in densely populated areas) to lower property values within a varying radius of the plant and is said to be one of the biggest disadvantages of a wind turbine This one along with the visual impact are the concerns often raised by members of the public, see, for example, Figures 10 and 11 concerning the public attitude toward the noise and visual impact in a Greek region where almost 120 MW of wind power operate since the beginning of the previous decade

The noise impact depends mainly on the average annual wind speed (i.e., the higher the wind speed, the greater the noise output can be) and the size of the blades Actually, wind noise is assumed analogous to the fourth to sixth power of the blades (tip) speed

noise emitted from a wind turbine [13] On the other hand, it is well known that the energy yield of a wind turbine is directly

is required in order to maximize the energy yield of a wind turbine Otherwise, the wind turbine would not operate efficiently In

where the machine operates at low rotational speed, reducing the noise emission and the power output as well On top of that, the energy in sound waves (and thus the sound intensity) in a homogeneous and obstacle-free flow field drops with the square of the distance from the sound source

In general, wind turbines generate noise as every machine does The noise from the wind turbine is divided into two major categories depending on the noise source, that is, the mechanical and the aerodynamic noise [14] Particularly,

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Example of an environmental impacts matrix of a wind park [11]

Activity

Removal of

construction, Setup of and Towers–turbines housing and Interconnection high-voltage and Wind equipment, Environmental Measurements site Delivery of temporary foundation assembly and substation from turbines power improvement farm’s Maintenance and power Site parameter Impact procedure demarcation equipment facilities works installation construction to substation network works operation needs lines remediation

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Noise Impact of Wind Parks in S Euboea

14%

Negligible Effects 39%

Covered by Surroundings 30%

Figure 10 Social evaluation of noise impact of wind parks in a selected Greek region where more than 120 MW of wind power are operating [12]

Visual Acceptance of Wind Parks in S Euboea

Figure 11 Social evaluation of visual impact of wind parks in a selected Greek region where more than 120 MW of wind power are operating [12]

• Mechanical noise is caused by rotating machinery such as the gearbox, electrical generator, and bearings (tonal sound) Normal wear and tear, poor component designs, or lack of preventative maintenance may all affect the amount of mechanical noise produced

• Aerodynamic noise is caused by the interaction of the turbine blades with the wind flow field Such a noise tends to increase significantly with the speed of the rotor as already mentioned For blade noise, lower blade tip speed results in lower noise levels,

Modern wind turbines produce little or no noise at all in comparison to their predecessors and to their rated power This is due to the fact that wind manufacturers realized quickly that the noise problem should be dealt with and started producing quieter machines after serious research efforts As a result, the noise from the gearbox and the blades has been reduced by careful attention

to the design and manufacture of the components and also the generator noise has been minimized with good sound insulation

Efforts have also been made for the reduction of the aerodynamic noise by:

• Decreasing rotational speed at the tip

• Using pitch control of upwind turbines in order to permit the rotation of the blades along their long axis, thus remarkably controlling the wind flow field around the airfoils

At any given location the noise varies considerably depending on the layout of the wind farm, the particular model of the turbines installed, the topography or shape of the land, the speed and the direction of the wind, and the background noise Wind turbine noise is characterized as very directional

The unit used to describe the intensity of sound is the decibel (dB) Audible sounds range from 0 dB (threshold of hearing) to

denoted as dB(A), approximates the range of human hearing by filtering out lower frequency noises, which are not as damaging as the higher frequencies It is used in most noise ordinances and standards

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Table 8 Sound levels of different sources/activities [9, 14]

To provide a frame of reference, rustling leaves have a decibel level of 10 dB(A); suburban expressway at 90 m, 60 dB(A); large truck pass-by at 15 m, 90 dB(A); and aircraft takeoff, 120 dB(A) Sound levels from various human activities is given in Table 8 Rationally, wind farms are always located where the wind speed is higher than average, and the background noise of the wind tends to cover any sounds that might be produced by operating wind turbines Background sound levels depend greatly on the location and presence of roads, trees, and other sound sources Typical background sound levels range from 35 dB(A) (quiet) to

50 dB(A) (urban setting)

emission source and eqn [3] can be used to add the turbine sound level to the background sound level to obtain the overall sound level [15]

center (m)

turbine level background level !

Figure 12 shows noise measurements taken at various distances from the wind turbine for various magnitudes of the background noise, included in the figure As expected, the background noise becomes prevalent as the distance increases, while the turbine noise

is discrete only in distances close to the turbine [15]

Noise impacts can also result from project construction and maintenance These are generally of relatively short duration and occurrence, but can include equipment operation, blasting, and noise associated with traffic into and out of the facility

Figure 12 Noise emission as a function of the distance from the wind turbine [15]

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Mechanical noise can be minimized at the design stage (e.g., side toothed gear wheels), or by acoustic insulation on the inside of the turbine housing Mechanical noise can also be reduced during operation by acoustic insulation curtains and anti-vibration support footings On the other hand, aerodynamic noise can be reduced by careful design of the blades by the manufacturers who can minimize this type of noise by better understanding the flow field pattern around the rotor of the machine

Wind direction has the tendency to increase noise level relative to the turbine and the receiving point The highest noise level can

be found at the bottom of the wind turbine situated with the wind direction from the plant toward the receiving point Noise of greatest concern can be generally classified as being of one of these three types:

Wind energy developers are required to meet local standards for acceptable sound levels; for example, in Germany, this level is

at higher speeds, noise produced by turbines can be (but is not always) masked by ambient noise

Noise emission measurements potentially are subject to serious problems to be overcome In addition, methods for assessing noise levels produced by wind turbines located in various terrains, such as mountainous regions, need further development Figure 13 shows a qualitative comparison of wind turbine and background noise as a function of the wind speed at 10 m height

opportunity of better investigating the real noise impact of the surroundings In this context, real-world noise measurements have significant value; for example, in a study by Kaldellis et al [14] measurements have been made and the results are compared with the theoretical (based on analytical methods) ones As can be shown from Figure 14, the experimental results are less than 50 dB(A), while the background noise in this specific area is almost 10 dB(A) lower than the noise emitted when the wind turbines operate Besides, the experimental measurements are fairly well harmonized with the theoretical ones (see also Figure 15)

Different types of wind turbines have different noise characteristics As mentioned earlier, modern upwind turbines are less noisy than downwind turbines Variable-speed turbines (where rotor speeds are lower at low wind speeds) create less noise at lower wind speeds when ambient noise is also low compared to constant-speed turbines Direct-drive machines, which have no gearbox or high-speed mechanical components, are normally quieter Various measures to reduce noise have been implemented in the design of modern turbines As wind turbines have become more efficient, more of the wind is converted into rotational torque and less into acoustic noise

In the design and the planning stage of a wind farm, semi-empirical prediction models and software tools are used to predict noise emissions Today, noise impact prediction is supported by the use of appropriate software The performance of a background noise survey around the site will help identify the dwellings that are most sensitive with respect to noise and the wind speed at which the greatest noise impact from the development will occur Special attention should be paid in analyzing the noise propagation pattern for all the basic wind directions, taking also into consideration the corresponding downwind geomorphology and topography Appropriate analytical methods can support the relevant surveys and advise on all stages of the process Acceptability standards for noise vary by nation, state, and locality They can also vary depending on time of day, since nighttime standards are generally stricter

Figure 13 Qualitative comparison of wind turbine noise and background noise as a function of wind speed at 10 m height [16]

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Wind Speed at 10m height (m/s)

Measurement Point: 100 m

Figure 14 Noise level measurements for different wind speed values [14]

Point 1-Near

Wind Speed at 10 m A (m/s)

Figure 15 Experimental measurements in comparison with the calculations using ISO-9613-2 and Danish Rules 2007 model [14]

2.16.6.2 Research and Development Relevant to Wind Turbine Noise

Acoustics researchers are investigating the causes of wind turbine noise with the aim of making them quieter Computer models are developed to predict the noise output from wind farms so that the effectiveness of potential noise-reducing designs and control methods to be accurately and quickly assessed

In fact, the noise generated from wind turbines is the same sort of noise generated at the edge of aircraft wings and is caused as the turbulent air flows over the sharp edge of the blade However, it is not known how the flow turbulence and the blade edge, or boundary layer, interact and how that makes the noise louder When this fundamental mechanism is understood, then ways of controlling and reducing the noise can be looked at, through perhaps changing the shape of the rotor blades (without reducing the machine efficiency) or using active control devices at the blade edges to disrupt the pattern of turbulence [16]

2.16.7 Wind Turbines ’ Visual Impact and Aesthetics

2.16.7.1 General Considerations on Visual Impact and Aesthetics

Windmills have been in operation during the last 1000 years all over Europe However, recently, due to the significant number and size of wind turbines installed, the matter of landscape aesthetics has been revived Actually, wind turbines have been subject to

exploit wind conditions

In this context, visual impacts are often among the major objections to the development of wind power systems, and a question that should not be ignored when trying to identify their location It is obvious that the reaction to the sight of a wind farm is highly

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Landscape Environment Human/Societal

Subjective Aesthetic Impact

Figure 16 Landscape and aesthetic impact: the three landscape domains

subjective Many people believe that they are a welcome symbol of clean energy, whereas others find them disturbing additions to the landscape Thus, although a wind plant is clearly a man-made structure, what it represents may be seen either as a positive or negative addition to the landscape More precisely, landscape perceptions and visual impacts are key environmental issues in determining wind farm applications, as landscape and visual impacts are, by nature, subjective and changing over time and location

components can be measured more easily as they are related to physical properties The aesthetic/human appraisal is much more complex since it depends on subjective landscape perception Figure 16 shows the major landscape domains

As far as the landscape components are concerned, in general, the visibility of a particular wind energy system will depend on many factors, including tower height, proximity to neighbors and roadways, local terrain and tree coverage, color or contrast, size, shadow flickering, the time when the turbine is moving or is stationary, the local turbine history, public acceptance, and knowledge

of renewable energy technologies Whatever the surrounding environment is, the developer should try to reduce the visual impact as much as possible

Table 9 is a synthesis of the various factors affecting seriously the visual impacts of a wind park

There is no doubt that the visual impacts decrease with the distance The affected areas are called zones and may be defined as indicated in Table 10

There are various methods for assessing the aesthetic impacts and many research works have been carried out either for the

information technology (IT) tools More specifically, a 3D analysis of the wind farm and its surrounding area is carried out to

Table 9 Various factors affecting the visual impacts of a wind park

Number of turbines Local terrain and tree coverage Size of the turbines Shadow flickering

Tower height Time that the turbine is stationery or moving Color and contrast of the turbines Access and site tracks

Form and appearance of the turbines Substation buildings Surface elevation and topography Grid connection Type of landscape Anemometer masts Proximity to neighbors and roadways Transmission lines

Table 10 Definition of zones according to the distance from the wind turbines [9]

Distance (depending on visibility and

Zone weather conditions) Characteristics – visibility

III 2–8 km (in good weather conditions) Noticeable, turbines clearly visible but not intrusive Turbines appear small in overall view

IV Over 7 km Element within distant landscape The apparent size of the turbines is very small, as any other

element in the landscape

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Diagonal

Diagonal Longitudinal

Diagonal

Longitudinal

Front Wind Farm Area Front

Figure 17 Points of view of a wind park [17]

obtain simulated images describing regions that are potentially affected Subsequently, a visual impact evaluation matrix applied over the neighboring villages is obtained The method uses geographical information systems (GIS) and computer-aided design (CAD) systems Figure 17 shows various views of a typical wind farm as elaborated for the method [17]

The basic objective of the method is to develop quantitative indexes for the rational evaluation of the visual impacts of a wind park The method has been applied by Tsoutsos et al [18] for the visual assessment of a wind park in the Greek island of Crete The basic steps that have been followed include the recording of the main parameters that affect the visibility of the wind turbines Also, the visibility of some points of interest around the wind park is investigated Accordingly, the calculation of properly defined coefficients to be used in the impact estimation is made, and finally, the total evaluation of the installation visual impact is performed

The process of recording the necessary coefficients for a typical medium-sized wind park located between two remote villages is shown in Figure 18

photographs and interviews to develop an objective indicator The indicator combines measures of visibility, color, fractality, and continuity that can be taken from photographs Value functions are constructed for each variable and incorporated into the indicator This indicator has been used to calculate the objective aesthetic impact of five wind farms Comparison of the indicator results with a population survey shows that the indicator correctly represents the order of impact as perceived by the population sample, and is thus an appropriate objective measure of aesthetic impact of wind farms

surveys to develop the proposed analysis are used The importance of parameters such as distance, contrast, and motion in the visual impact assessment with the use of photographs, computer simulations, and interviews is mentioned by Bishop and Miller [21] According to the results of this work, the visual impacts are reduced as the distance increases from the wind park These methodologies are useful for the assessment of the visual impact of a single technology (e.g., wind farms) on the local scale (a single project)

Subsequently, in the work of Molina-Ruiz et al [22] the use of IT tools is examined (Geographical Information Systems and Multi-Criteria Decision Analysis) to facilitate the visual impact evaluation Accordingly, Rodrigues et al [23] suggested a method for the global assessment of the visual impact on the landscape of renewable energy A number of quantitative indexes for the visual impact (objective) and the visual perspective (subjective) estimations are introduced For the visual impact index estimation, a process for determining whether a location is visually affected by a wind park or not is presented (Figure 19)

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