wind site assessment

A wind site assessment consists of a combination of processes used to estimate the particular site conditions affecting a wind farm. The accuracy of this estimation is crucial to the long-lasting performance of a wind farm.

The site assessment of a wind project includes the analysis of some variables affecting the performance of the wind turbines, such as the turbulence intensity or the extreme wind gusts, and other topics affecting the populations such as the shadow flicker or the noise affection.

What does a wind site assessment include?

Verification of the suitability of a specific wind turbine model to the local site conditions is of critical importance in the success of a wind project. Nayxa’s teams of experts accumulate a vast experience in the calculation of the effective turbulence intensity, the Vref parameter, inflow angles or temperature patterns.

In order to carry out a good site assessment, it is necessary to have quality inputs. Therefore, it will be fundamental to build high quality topographic and roughness maps. At Nayxa we manually digitalize roughness maps, which reflect with great precision, the existing vegetation around the wind farm project. Topographic and roughness maps have an impact on turbulence, flow inclination and local speed up effects which are key factors in the selection of the most adequate wind turbine model.

Wind farms also affect the population, generating acoustic nuisances, flickering shadows or visual impacts. These affections are specific to each site and project and must be conveniently analyzed prior to the construction of the wind farm. If necessary, corrective strategies must be implemented to avoid problems for the population.

Wind turbine site assessment

A wind farm should perform without much trouble a period between 20 and 30 years. A site assessment analysis aims to extend the useful life of the wind turbines as well as minimize certain maintenance tasks, which translates into clear improvements in the economic models of the projects.

What is a wind turbine site assessment?

A wind turbine site assessment consists of a combination of processes used to analyze some variables affecting the performance of the wind turbines, such as the effective turbulence intensity, the Vref parameter, inflow angles or temperature patterns. All these magnitudes affect the loading of a wind turbine and should be characterize before the installation of a wind farm.

What is the target of a wind turbine site assessment?

The objective of a site assessment is to characterize the specific wind conditions of a site where a wind farm is being planned, in order to select the most suitable wind turbine with the best performance. A quality site assessment allows the wind turbine manufacturer to modify some settings of the selected wind turbine model, in order to extend its useful life.

Important factors in a wind turbine site assessment

In order to carry out a good site assessment, it is necessary to have quality inputs. Therefore, it will be fundamental to build detailed topographic and roughness maps. A quality measurement campaign, with enough measurement points (especially in complex terrain), is essential to be able to carry out an accurate and high-standard wind turbine site assessment.

Roughness maps

The land use or terrain roughness is defined as the set of obstacles and vegetation affecting the wind speed in the surface layer of the atmosphere which directly impacts the operation of wind turbines. The terrain roughness affects the way wind speed changes with height and therefore the energy produced by a wind turbine.

What is a roughness maps?

A roughness map is a set of contour lines or pixel points defining the different types of vegetation or obstacles existing in the area of affection of a wind farm. It is recommended to build roughness maps within a perimeter of 10km around the wind turbine locations and most importantly, that the generated map reflects the real existing vegetation.

What is the mission of a roughness map?

The mission of a roughness map is to define the existing vegetation around a wind farm. The terrain roughness affects important magnitudes such as the wind speed, the turbulence intensity, or the wind shear, among others. All these variables have an impact on the energy produced by a wind farm and on the expected level of loads which are analyzed in the wind turbine site assessment.

Important factors in making a roughness map

Perhaps the most important factor when building a high-quality roughness map is that the map reliably reflects the existing vegetation in our project site. Our experience tells us that only hand-digitized maps meet this condition and that is why at Nayxa only our engineers prepare the roughness maps, leaving aside the automatic algorithms and processes. This has a major impact in the quality of the resulting map.

Shadow flicker

The rotating blades of a wind turbine can cast a moving shadow on locations surrounding a wind farm. These moving shadows are called shadow flicker and can be a nuisance to people at nearby residential areas or public gathering places, such as schools. The impact depends on the wind farm location, time of year and day and the wind turbine characteristics (height, size, and orientation of the rotor blades).

What is a shadow flicker assessment?

A shadow flicker assessment aims to quantify the effect of shadows caused by the rotating blades of wind turbines in potential areas of influence located near the wind farm, such as homes, schools, farms, or recreational areas. The output of this analysis is a daily distribution of hours in which this affection will take place.

What is the goal of a shadow flicker assessment?

The objective of a shadow flicker analysis is to identify spots in the community in which the limits allowed for this type of annoying phenomenon are expected to be exceeded, in order to implement corrective measures to minimize these nuisances. A detailed and professional shadow flicker analysis is recommended due to the potential implications for all the parties.

Important factors in a shadow flicker analysis

Perhaps the most important factor at the time of analyzing the shadow flicker of a wind farm, is that the results reliably reflect the real affection to the population. The amount of shadow flicker determined by the theoretical models should be limited by factors such as cloudiness, site wind rose, presence of obstacles, terrain characteristics or turbine operation. Nayxa’s team of experts can support you in this analysis.

Noise analysis

The rotating blades of a wind turbine create an acoustic impact on locations surrounding a wind farm. This affection, apart from being a risk to health problems, constitutes a nuisance to people at nearby residential areas or public gathering places, such as schools. It is a permanent impact under turbine operation, and it depends on the wind turbine characteristics (height, size, and operation mode of the wind turbine) and distance to the Community.

What is a noise analysis?

A noise analysis aims to quantify the effect of the acoustic noise caused mainly by the rotating blades of wind turbines in possible areas of influence located near the wind farm, such as homes, schools, farms, or recreational areas. International and / or national regulations should be respected since noise disturbances cause serious health problems to the population.

What is the mission of a noise analysis?

The objective of a noise analysis is to identify spots in the community in which the limits allowed for this type of annoying phenomenon are expected to be exceeded, in order to implement corrective measures to minimize these nuisances. A detailed and professional noise analysis is recommended due to the potential implications for all the parties.

Important factors in making a noise analysis

When carrying out the analysis of the acoustic impact of a wind farm, it is necessary to have quality inputs, as well as reliable software, which are capable of building accurate predictions. The experience of the engineer is also very important due to the sensitivity of the results and their potential effects and implications.

How is a wind site assessment done at Nayxa?

Nayxa Energy Services accumulates more than 15 years of experience in wind site assessment. We incorporate the know-how we acquire from each project into our work procedures in order to improve continuously our methodology and quality. (Experience and Know-How).

Our team of engineers have been analyzing the wind site assessment of multiple projects since 2009. We have faced multiple challenges under all sort of climates at different geographical regions which have strengthened our know-how and therefore improve the reliability of our results and advising.

Our services in wind site assessment

If you are passionate about the wind resource assessment, do not hesitate to contact us, we will be happy to hear from you.

Wind turbine site assessment

Nayxa has carried out more than 150 site assessment studies for different wind turbine manufacturers under all types of weather conditions. From our experience, we are aware of the importance of performing an accurate effective turbulence intensity calculation, as well as designing shutdown strategies that minimize production losses.

Manual production of high-resolution roughness maps.

Nayxa has been involved in projects where the international bases of land use are not capable of faithfully reproducing the real existing vegetation. This can give rise to errors in the modeling and in the results of different variables such as the energy yield, the vertical profile, or the turbulence intensity. Hand-digitized maps constitute an alternative with more accuracy and resolution than automatically generated roughness maps.

Shadow flicker assessment and noise studies.

At Nayxa we are aware of the importance of shadow flicker and noise analysis results, both for wind farm developers and for the affected population. That is why we carry out very precise calculations with the aim of reflecting, as far as possible, the reality of the problem and we help all parties to find the optimal solution. We also help all the parties to implement corrective strategies.

Consultancy service in Due Diligence processes of wind assets

In a due diligence process of a wind asset, both aspects related to the wind resource assessment (wind measurement campaign, wind farm design, energy yield …) and the site assessment (analysis of the effective turbulence intensity, loads on the wind turbines or effects on the population such as visual impacts, shadow flicker or noise disturbances) should be carefully analyzed in order to emit a verdict on the benefits versus handicaps of the project.

Maps of wind speed anomalies (wind index) and special projects

At Nayxa we can help you if you have a special project related to wind resource assessment or site assessment. As a result of our continuous research, products such as the wind anomaly maps, (wind index), have emerged, which provide us, at any geographical level, with an indicator of wind productivity in a given period of time with respect to the historical level.

FAQ About the wind site assessment

The purpose of a wind site assessment is to estimate the particular site conditions affecting a wind farm. Verification of the suitability of a specific wind turbine model to the local site conditions is of critical importance in the success of a wind project. Potential nuisances to the population such as shadow flicker or acoustic impacts should also be analyzed.

The site assessment of a wind project includes the analysis of some variables affecting the performance of the wind turbines, such as the turbulence intensity, extreme wind gusts or inflow angles, and other topics affecting the populations such as the shadow flicker, visual impacts, or noise nuisances.

Life expectancy of wind turbines is analyzed in the site suitability report of a wind farm, which is the output of a wind turbine site assessment. The accuracy of this process plays a fundamental role in the success of the project and in its economic model. Other aspects such as shadow flicker or acoustic impacts are equally important to avoid nuisances and health problems to the population.

A roughness map is a set of contour lines or pixel points defining the different types of vegetation or obstacles existing in the area of affection of a wind farm. The most important factor when building a quality roughness map is that the map reliably reflects the existing vegetation in our project site. Our experience tells us that only hand-digitized maps meet this condition and that is why at Nayxa only our engineers prepare the roughness maps, leaving aside the automatic algorithms and processes.

A shadow flicker analysis aims to quantify the effect of shadows caused by the rotating blades of wind turbines in potential areas of influence located near the wind farm, such as homes, schools, farms, or recreational areas. The impact depends on the wind farm location, time of year and day and the wind turbine characteristics (height, size, and orientation of the rotor blades).

If you are interested in requesting a request to carry out wind measurement campaigns in your wind energy project, do not hesitate to contact our team.

You can contact us at +34 91 241 15 97​, send an email to info@nayxa.com or you can leave your data in the contact form here