A Review of Numerical Modelling of Multi-Scale Wind Turbines and Their Environment <s> Introduction <s> Wind-farms receive public and governmental support as an alternative energy source mitigating air pol- lution. However, they can have adverse effects on wildlife, particularly through collision with turbines. Research on wind-farm effects has focused on estimating mortality rates, behavioural changes or inter- specific differences in vulnerability. Studies dealing with their effects on endangered or rare species pop- ulations are notably scarce. We tested the hypothesis that wind-farms increase extinction probability of long-lived species through increments in mortality rates. For this purpose, we evaluate potential conse- quences of wind-farms on the population dynamics of a globally endangered long-lived raptor in an area where the species maintains its greatest stronghold and wind-farms are rapidly increasing. Nearly one- third of all breeding territories of our model species are in wind-farm risk zones. Our intensive survey shows that wind-farms decrease survival rates of this species differently depending on individual breed- ing status. Consistent with population monitoring, population projections showed that all subpopulations and the meta-population are decreasing. However, population sizes and, therefore, time to extinction sig- nificantly decreased when wind-farm mortality was included in models. Our results represent a qualita- tive warning exercise showing how very low reductions in survival of territorial and non-territorial birds associated with wind-farms can strongly impact population viability of long-lived species. This highlights the need for examining long-term impacts of wind-farms rather than focusing on short-term mortality, as is often promoted by power companies and some wildlife agencies. Unlike other non-natural causes of mortality difficult to eradicate or control, wind-farm fatalities can be lowered by powering down or removing risky turbines and/or farms, and by placing them outside areas critical for endangered birds. 2009 Elsevier Ltd. All rights reserved. <s> BIB001 </s> A Review of Numerical Modelling of Multi-Scale Wind Turbines and Their Environment <s> Introduction <s> Building-integrated micro-wind turbines are promising low-cost renewable energy devices. However, the take-up of micro-wind turbines in high density suburban environments is still very limited due to issues such as: a) low wind speeds; b) high turbulence intensity; and c) the perception of potentially high levels of aerodynamic noise generated by the turbines. The wind flow field above the roof of buildings in this environment is different to that over flat terrain or around isolated buildings. The effect of the local suburban topology on the wind speed and turbulence intensity fields in a given locality is therefore an important determinant of the optimal location of micro-wind turbines. This paper presents a numerical study of above roof wind flow characteristics in three suburban landscapes characterized by houses with different roof profiles, namely: pitched roofs, pyramidal roofs and flat roofs. Computational Fluid Dynamic (CFD) technique has been used to simulate the wind flow in such environments and to find the optimum turbine mounting locations. Results show how the wind flow characteristics are strongly dependent on the profile of the roofs. It is found that turbines mounted on flat roofs are likely to yield higher and more consistent power for the same turbine hub elevation than the other roof profiles. <s> BIB002 </s> A Review of Numerical Modelling of Multi-Scale Wind Turbines and Their Environment <s> Introduction <s> BackgroundWind power has been harnessed as a source of power around the world. Debate is ongoing with respect to the relationship between reported health effects and wind turbines, specifically in terms of audible and inaudible noise. As a result, minimum setback distances have been established world-wide to reduce or avoid potential complaints from, or potential effects to, people living in proximity to wind turbines. People interested in this debate turn to two sources of information to make informed decisions: scientific peer-reviewed studies published in scientific journals and the popular literature and internet.MethodsThe purpose of this paper is to review the peer-reviewed scientific literature, government agency reports, and the most prominent information found in the popular literature. Combinations of key words were entered into the Thomson Reuters Web of KnowledgeSM and the internet search engine Google. The review was conducted in the spirit of the evaluation process outlined in the Cochrane Handbook for Systematic Reviews of Interventions.ResultsConclusions of the peer reviewed literature differ in some ways from those in the popular literature. In peer reviewed studies, wind turbine annoyance has been statistically associated with wind turbine noise, but found to be more strongly related to visual impact, attitude to wind turbines and sensitivity to noise. To date, no peer reviewed articles demonstrate a direct causal link between people living in proximity to modern wind turbines, the noise they emit and resulting physiological health effects. If anything, reported health effects are likely attributed to a number of environmental stressors that result in an annoyed/stressed state in a segment of the population. In the popular literature, self-reported health outcomes are related to distance from turbines and the claim is made that infrasound is the causative factor for the reported effects, even though sound pressure levels are not measured.ConclusionsWhat both types of studies have in common is the conclusion that wind turbines can be a source of annoyance for some people. The difference between both types is the reason for annoyance. While it is acknowledged that noise from wind turbines can be annoying to some and associated with some reported health effects (e.g., sleep disturbance), especially when found at sound pressure levels greater than 40 db(A), given that annoyance appears to be more strongly related to visual cues and attitude than to noise itself, self reported health effects of people living near wind turbines are more likely attributed to physical manifestation from an annoyed state than from wind turbines themselves. In other words, it appears that it is the change in the environment that is associated with reported health effects and not a turbine-specific variable like audible noise or infrasound. Regardless of its cause, a certain level of annoyance in a population can be expected (as with any number of projects that change the local environment) and the acceptable level is a policy decision to be made by elected officials and their government representatives where the benefits of wind power are weighted against their cons. Assessing the effects of wind turbines on human health is an emerging field and conducting further research into the effects of wind turbines (and environmental changes) on human health, emotional and physical, is warranted. <s> BIB003 </s> A Review of Numerical Modelling of Multi-Scale Wind Turbines and Their Environment <s> Introduction <s> The urban terrain and the associated morphological complexities therein, present significant challenges for the deployment of small wind turbines. In particular, a considerable amount of uncertainty is attributable to the lack of understanding concerning how turbulence within urban environments affects turbine productivity. Current wind turbine power output measurements (particularly for small/micro wind turbines) are based on an average wind speed over an observation period; with limited accountability of the variability of wind speed within the observation time frame. This paper however, presents two models that can instead accurately consider such wind speed variation and how it affects the turbine, based solely on the observed mean wind speed and standard deviation within successive (10 min) time intervals. These models are predicated on an appreciation of the industry standard metric, turbulence intensity (TI), in conjunction with the power curve of a 2.5 kW wind turbine. Simple ‘look-up’ tables collating how the turbine's power curve is affected by varying TI are used so that a novel methodology for estimating the turbine's electrical performance is achievable. Ultimately, the two models presented afford an opportunity to provide an indicative real-world wind speed distribution based on the two standard measurements. The first approach is an adaptation of a model originally derived to quantify the degradation of power performance of wind farm turbines, using a Gaussian probability distribution to simulate turbulence (and more specifically, turbulence intensity (TI)). Such Gaussian modelling has potential however, for disproportionately high and asymptotic TI, associated, for example, with gusting within low mean wind speed observation windows. Furthermore, the approach requires an accurate turbine power curve. The second approach overcomes these limitations through the novel application of the Weibull Distribution, a widely accepted means to probabilistically describe wind speed. Both models are tested at an urban and suburban location in Dublin City, Ireland, where sonic anemometry is positioned at approximately 1.5 times the average height of buildings at the respective locations. Both observation sites represent two distinct urban landscapes. The instrumentation is positioned specific to their surrounding locations and, record the three dimensional wind vectors at a temporal resolution of 10 Hz. The hypotheses presented here consider an idealised electrical performance of the turbine, with results suggesting that both approaches can replicate very accurately this idealised basis. <s> BIB004 </s> A Review of Numerical Modelling of Multi-Scale Wind Turbines and Their Environment <s> Introduction <s> Noise concerns frequently pose a barrier to widespread implementation of wind turbines and while the perception of noise from large turbines has been investigated, there is a relative gap in the research for small and micro wind turbines. This paper presents findings from interdisciplinary research linking noise measurements from small wind installations with an investigation into the effect of individual personality traits and noise perception. A survey distributed to households living close to one of 12 micro or small turbine sites, coupled with environmental noise measurements was analysed. The survey showed that the most commonly perceived noises are ‘swooshing’ and ‘humming’, the presence of which may be inferred from the measured frequency spectra. Exploration of survey results showed individuals with a more negative attitude to wind turbines perceive more noise from a turbine located close to their dwelling and those perceiving more noise report increased levels of general symptoms. Individuals' personality also affected attitudes to wind turbines, noise perception from small and micro turbines and symptom reporting. <s> BIB005 </s> A Review of Numerical Modelling of Multi-Scale Wind Turbines and Their Environment <s> Introduction <s> This paper evaluates the life cycle environmental sustainability of micro-wind turbines in the UK in comparison with grid electricity and solar PV (photovoltaics). The results suggests that per kWh electricity generated, the majority of environmental impacts from the wind turbines are lower than from grid electricity, ranging from 26% lower terrestrial toxicity to 92% lower global warming. However, depletion of abiotic elements, fresh-water and human toxicities are 82%, 74% and 53% higher than for grid electricity, respectively. The wind turbines are more environmentally sustainable than solar PV for seven out of 11 impacts, ranging from 7.5% lower eutrophication to 85% lower ozone layer depletion. However, depletion of fossil resources, fresh-water, human and terrestrial toxicities are higher for the wind turbine than for the PV, ranging from 5% for the former to 87% for the latter. UK-wide deployment of micro-wind turbines would save between 0.6 and 1% of GHG (greenhouse gas) emissions on 2009 levels. Therefore, the potential of micro-wind turbines to contribute towards UK's climate change targets is limited. <s> BIB006 </s> A Review of Numerical Modelling of Multi-Scale Wind Turbines and Their Environment <s> Introduction <s> This work was supported by the Engineering and Physical Sciences Research Council and Quiet Revolution Ltd. <s> BIB007 </s> A Review of Numerical Modelling of Multi-Scale Wind Turbines and Their Environment <s> Introduction <s> This article examines the efficiency of wind energy production. Using non-convex efficiency analysis, we quantify production losses for 19 wind turbines in four wind parks across Germany. In a second stage regression, we adapt the linear regression results of Kneip, Simar, and Wilson (2014) to explain electricity losses by means of a bias-corrected truncated regression analysis. The results show that electricity losses amount to 27% of the maximal producible electricity. Most of these losses are from changing wind conditions, while 6% are from turbine errors. <s> BIB008 </s> A Review of Numerical Modelling of Multi-Scale Wind Turbines and Their Environment <s> Introduction <s> Abstract To create a clean energy environment for the future found to be as one of the great challenges of our time. As conventional sources (i.e. oil, coal, Fossil Fuels) of energy depleting very rapidly and will be finished in near future, it is very essential to look for renewable energy sources. To incorporate this challenge in India a systematic new energy plan was developed in 2006 i.e. Ministry of New and Renewable Energy (MNRE). Harvard University study, published in the Proceedings of the National Academy of Sciences of the United States 2009, had calculated that the future world’s wind power potential to be 40 times greater than current power consumption. The most important component of wind energy converter is rotor, which rotate and produces electricity. The objective of this project is to design a rotor blade for Reynolds number 100,000. Design procedure consists of selection of suitable air foil (for small scale Horizontal Axis Wind Turbine), determination of twist and chord along the blade radius, and modelling is done on Creo-Parametric 5.0. Aerodynamic analysis is performed through Blade Element Momentum (BEM) theory which gives optimize torque and power. Performance is analysed for wind velocity 4-7 m/s at different tip speed ratio (TSR). Performance is validated with the help of CFD (ANSYS 14.0). After analysis, it is found that the power developed is 250W with coefficient of power 35.687%. <s> BIB009 </s> A Review of Numerical Modelling of Multi-Scale Wind Turbines and Their Environment <s> Introduction <s> A wind turbine is a very well-known archetype of energy conversion system working at non-stationary regimes. Despite this, a deep mechanical comprehension of wind turbines operating in complicated conditions is still challenging, especially as regards the analysis of experimental data. In particular, wind turbines in complex terrain represent a very valuable testing ground because of the possible combination of wake effects among nearby turbines and flow accelerations caused by the terrain morphology. For these reasons, in this work, a cluster of four full-scale wind turbines from a very complex site is studied. The object of investigation is vibrations, at the level of the structure (tower) and drive-train. Data collected by the on-board condition monitoring system are analyzed and interpreted in light of the knowledge of wind conditions and operating parameters collected by the Supervisory Control And Data Acquisition (SCADA). A free flow Computational Fluid Dynamics (CFD) simulation is also performed, and it allows one to better interpret the vibration analysis. The main outcome is the interpretation of how wakes and flow turbulences appear in the vibration signals, both at the structural level and at the drive-train level. Therefore, this wind to gear approach builds a connection between flow phenomena and mechanical phenomena in the form of vibrations, representing a precious tool for assessing loads in different working conditions. <s> BIB010 </s> A Review of Numerical Modelling of Multi-Scale Wind Turbines and Their Environment <s> Introduction <s> The increasing focus on the installation of sustainable energy systems has resulted in a wide range of micro wind turbine systems being introduced in the market. Although the majority of the commercially installed wind turbines are the horizontal axis ones, vertical axis turbines are considered as a promising technology for the future. It is generally known that the environmental impacts generated in the operational stage of wind turbines are significantly lower than the ones, generated by the fossil fuels based systems. The use of the Life Cycle Assessment (LCA) enables to assess the environmental impacts of a product or a process, taking into consideration also raw material extraction, manufacturing, distribution, and disposal stages of life cycle. The contribution of these stages is often critical for the environmental impacts of the bioenergy systems. This study contributes to the existing knowledge by presenting the detailed LCA of electricity produced in micro wind turbines with the vertical axis. For the impact assessment, two methods were selected: the CML-IA and Thermo-Ecological Cost in the whole life cycle (TEC-LC). Firstly, the environmental impacts of electricity generated by wind turbines with 1 and 3 kW nominal power were evaluated and compared with each other and with the impacts of the grid electricity produced in the Italian energy mix. Next, the sensitivity of the impact results on the wind characteristics variability was investigated. Results showed that the 3 kW turbine has, in general, lower values of the environmental impact indicators per unit of produced energy than the 1 kW turbine from 27% lower Global Warming Potential (GWP) to 75% lower Abiotic Depletion (ADP). The impacts per unit of produced energy in the analysed micro wind turbines are lower than the corresponding impacts for the grid electricity generated in the Italian energy mix for nine impact indicators out of twelve. It was also observed that wind distribution parameters strongly influence the environmental impacts of the electricity produced by the considered turbines, leading to values higher than those obtained for Italian energy mix for low wind average speed and, even more, for low variances of the average wind speed. <s> BIB011 </s> A Review of Numerical Modelling of Multi-Scale Wind Turbines and Their Environment <s> Introduction <s> Abstract As a renewable energy source, wind power has received growing attentions, but mostly been utilized in wind power farms or high-rise buildings where the wind with high speed is available. Few studies focus on the micro-wind utilization in low-rise buildings due to the bottleneck that the wind speed cannot meet the minimal speed requirement of small wind turbines. This paper aims to identify the optimal building design which could enable the harvesting of the maximal micro-wind power around low-rise residential buildings. Based on the comparison among different building shapes and the computational fluid dynamics (CFD) analysis via software Phoenics , this paper identified that the building shape of “composite prism” could enable the harvesting of the most micro-wind power. The identified building shape was then tested in a simulated environment of a residential community in Pingtan Island, China. The local wind conditions, long-term community planning, and the requirement of comfort level were all considered in the simulation model. The result shows that the potential of utilizing wind energy in low-rise residential buildings is huge by adopting the proposed building shape of “composite prism”. The finding has significant implications for renewable energy utilization in built environment. <s> BIB012 </s> A Review of Numerical Modelling of Multi-Scale Wind Turbines and Their Environment <s> Introduction <s> Low-powered devices are ubiquitous in this modern age especially their application in the urban and built environment. The myriad of low-energy applications extend from wireless sensors, data loggers, transmitters and other small-scale electronics. These devices which operate in the microWatt to milliWatt power range and will play a significant role in the future of smart cities providing power for extended operation with little or no battery dependence. Low energy harvesters such as the aero-elastic belt are suitable for integration with wireless sensors and other small-scale electronic devices and therefore there is a need for studying its optimal installation conditions. In this work, a case study presenting the Computational Fluid Dynamics modelling of a building integrated with aero-elastic belts (electromagnetic transduction type) was presented. The simulation used a gable-roof type building model with a 27° pitch obtained from the literature. The atmospheric boundary layer flow was employed for the simulation of the incident wind. The work investigates the effect of various wind speeds and aero-elastic belt locations on the performance of the device giving insight on the potential for integration of the harvester into the built environment. ::: ::: The apex of the roof of the building yielded the highest power output for the aero-elastic belt due to flow speed-up maximisation in this region. This location produced the largest power output under the 45° angle of approach, generating an estimated 62.4 mW of power under accelerated wind in belt position of up to 6.2 m/s. For wind velocity of 10 m/s, wind in this position accelerated up to approximately 14.4 m/s which is a 37.5% speed-up at the particular height. This occurred for an oncoming wind 30° relative to the building facade. For velocity equal to 4.7 m/s under 0° wind direction, airflows in facade edges were the fastest at 5.4 m/s indicating a 15% speed-up along the edges of the building. <s> BIB013 </s> A Review of Numerical Modelling of Multi-Scale Wind Turbines and Their Environment <s> Introduction <s> With the ubiquity of low-powered technologies and devices in the urban environment operating in every area of human activity, the development and integration of a low-energy harvester suitable for smart cities applications is indispensable. The multitude of low-energy applications extend from wireless sensors, data loggers, transmitters and other small-scale electronics. These devices function in the microWatt-milliWatt power range and will play a significant role in the future of smart cities providing power for extended operation with little or no battery dependence. This study thus aims to investigate the potential built environment integration and energy harvesting capabilities of the Wind-Induced Flutter Energy Harvester (WIFEH) – a microgenerator aimed to provide energy for low-powered applications. Low-energy harvesters such as the WIFEH are suitable for integration with wireless sensors and other small-scale electronic devices; however, there is a lack in study on this type of technology’s building integration capabilities. Hence, there is a need for investigating its potential and optimal installation conditions. ::: ::: This work presents the experimental investigation of the WIFEH inside a wind tunnel and a case study using Computational Fluid Dynamics (CFD) modelling of a building integrated with a WIFEH system. The experiments tested the WIFEH under various wind tunnel airflow speeds ranging from 2.3 to 10 m/s to evaluate the induced electromotive force generation capability of the device. The simulation used a gable-roof type building model with a 27° pitch obtained from the literature. The atmospheric boundary layer (ABL) flow was used for the simulation of the approach wind. The work investigates the effect of various wind speeds and WIFEH locations on the performance of the device giving insight on the potential for integration of the harvester into the built environment. The WIFEH was able to generate an RMS voltage of 3 V, peak-to-peak voltage of 8.72 V and short-circuit current of 1 mA when subjected to airflow of 2.3 m/s. With an increase of wind velocity to 5 m/s and subsequent membrane retensioning, the RMS and peak-to-peak voltages and short-circuit current also increase to 4.88 V, 18.2 V, and 3.75 mA, respectively. For the CFD modelling integrating the WIFEH into a building, the apex of the roof of the building yielded the highest power output for the device due to flow speed-up maximisation in this region. This location produced the largest power output under the 45° angle of approach, generating an estimated 62.4 mW of power under accelerated wind in device position of up to 6.2 m/s. For wind velocity (UH) of 10 m/s, wind in this position accelerated up to approximately 14.4 m/s which is a 37.5% speed-up at the particular height. This occurred for an oncoming wind 30° relative to the building facade. For UH equal to 4.7 m/s under 0° wind direction, airflows in facade edges were the fastest at 5.4 m/s indicating a 15% speed-up along the edges of the building. <s> BIB014
Over the last decade, the production of renewable energy has rapidly increased and this development is expected to continue. Wind energy generation contributed a great share to this expansion and has attracted institutional investors. Wind resource is one of the most used sources of energy and about 50 GW have been installed in the year 2014  . The global warming effect, increasing price of fossil products, instability of the energy market, and desire for clean-smart cities are the main drivers for increasing awareness in renewable technologies. Creating an environment which is clean and sustainable for the future is one of the greatest challenges of our time. As conventional sources like coal, oil, and other fossil fuels are limited and continue to be depleted, it is very important to search for renewable energy sources and develop technologies BIB009 . Researchers continue to develop and optimise wind turbines to eliminate the drawbacks associated with these devices. Due to all of these issues, the trend of increasing production from wind power resulted in wind farm constructions in locations with highly complex orography and, therefore, predicting its performance using simplified and linear models may not be adequate or accurate enough. The installation of wind turbines in complex terrain landscapes represents a major challenge due to the combination of uncertain wind resources and the flow accelerations from the surrounding terrain and wake effects from other turbines BIB010 . Another example is the installation of wind turbines in buildings or building-integrated wind turbines (BIWT), where the wind resource and condition are uncertain due to the surrounding buildings. The profitability of energy production from wind resource is dependent on the turbine productivity, price of energy and generation costs, taking into account the total cost over the entire lifetime BIB008  . Micro-siting or the selection of the most efficient and effective type of wind turbine and exact location are very important factors that should be considered during the planning stage of a wind energy project. A lot of present tools/methods are not sufficient to completely predict the wind flow multifaceted and complex settings where the estimation of acceleration-deceleration wind effects is challenging. The error associated with the energy data presents a growing issue as the accuracy concerning the quantity of the energy which could be commercialised is even greater. Recent studies have shown that the integration of numerical Computational Fluid Dynamics (CFD) modelling with other tools such as wind tunnel or field measurements could provide a solution for the assessment of wind power in complex conditions BIB004 7] . Complex conditions, specifically in urban areas, presents substantial challenges for the integration of wind turbines. Also, there is lack of understanding and uncertainty concerning the impact of turbulence on the effectiveness of wind turbines in urban areas. Figure 1 shows the different sizes and capacities of wind turbines [7] . A number of exhaustive studies have been made in small and medium scale wind turbine blades and most of them have used CFD and traditional BEM or blade element momentum to design the blades and compute the forces that act on it. Many studies on searching the optimum chord lengths have been prepared using different evolutionary optimising strategies. Issues including high turbulence, low wind velocity, and frequent direction of the wind change can affect the performance of HAWT or Horizontal-Axis Wind Turbine. Some VAWT or Vertical-Axis Wind Turbine designs can operate well in complex operating conditions however many possess low power coefficient  9] . Computation 2017, 5, x FOR PEER REVIEW 2 of 37 continue to develop and optimise wind turbines to eliminate the drawbacks associated with these devices. Due to all of these issues, the trend of increasing production from wind power resulted in wind farm constructions in locations with highly complex orography and, therefore, predicting its performance using simplified and linear models may not be adequate or accurate enough. The installation of wind turbines in complex terrain landscapes represents a major challenge due to the combination of uncertain wind resources and the flow accelerations from the surrounding terrain and wake effects from other turbines BIB010 . Another example is the installation of wind turbines in buildings or building-integrated wind turbines (BIWT), where the wind resource and condition are uncertain due to the surrounding buildings. The profitability of energy production from wind resource is dependent on the turbine productivity, price of energy and generation costs, taking into account the total cost over the entire lifetime BIB008  . Micro-siting or the selection of the most efficient and effective type of wind turbine and exact location are very important factors that should be considered during the planning stage of a wind energy project. A lot of present tools/methods are not sufficient to completely predict the wind flow multifaceted and complex settings where the estimation of acceleration-deceleration wind effects is challenging. The error associated with the energy data presents a growing issue as the accuracy concerning the quantity of the energy which could be commercialised is even greater. Recent studies have shown that the integration of numerical Computational Fluid Dynamics (CFD) modelling with other tools such as wind tunnel or field measurements could provide a solution for the assessment of wind power in complex conditions BIB004 7] . Complex conditions, specifically in urban areas, presents substantial challenges for the integration of wind turbines. Also, there is lack of understanding and uncertainty concerning the impact of turbulence on the effectiveness of wind turbines in urban areas. Figure 1 shows the different sizes and capacities of wind turbines [7] . A number of exhaustive studies have been made in small and medium scale wind turbine blades and most of them have used CFD and traditional BEM or blade element momentum to design the blades and compute the forces that act on it. Many studies on searching the optimum chord lengths have been prepared using different evolutionary optimising strategies. Issues including high turbulence, low wind velocity, and frequent direction of the wind change can affect the performance of HAWT or Horizontal-Axis Wind Turbine. Some VAWT or Vertical-Axis Wind Turbine designs can operate well in complex operating conditions however many possess low power coefficient  9] . Buildings or roofs integrated with micro-wind turbines are also creating great attention for decentralised power production and promising low cost renewable energy devices in populated areas, but, there is an uncertainty concerning the viability of these wind turbines. In high density urban/suburban areas, the installation of wind turbines is fairly limited because of problems including high turbulence intensity, low wind speeds, and possibly of greater levels of noise Buildings or roofs integrated with micro-wind turbines are also creating great attention for decentralised power production and promising low cost renewable energy devices in populated areas, but, there is an uncertainty concerning the viability of these wind turbines. In high density urban/suburban areas, the installation of wind turbines is fairly limited because of problems including high turbulence intensity, low wind speeds, and possibly of greater levels of noise produced by the turbine. In order to make use of the application of micro-small renewable-energy production, Computation 2018, 6, 24 3 of 37 particularly smaller turbines, allowing for tower heights that permits max utilisation of the accessible wind resource is important BIB002 . Between the different classifications of wind systems, small-scale VAWT showed the greatest potential for the generation of power in off-grid locations BIB007 . But the wind turbines are mostly being utilised in wind power farms or high-rise buildings where the wind with high speed is available. Few studies focus on the micro-wind utilisation in low-rise buildings due to the bottleneck i.e., wind speed cannot meet the minimal speed requirement of small wind turbines. Recently, the optimisation of wind farms using CFD has received much attention in literature. For uniform terrains, the wind farm layout optimisation has been addressed through many works using various strategies; but currently, optimising the layout of wind farm on non-uniform/complex terrains is a challenge because of the absence of accurate and computationally tractable wake models for the assessment of the layout of wind farm. CFD modelling solutions such as actuator-disk and -line were established to predict the interaction with non-uniform terrains and phenomena of wake though these methods are computationally expensive particularly during the process of optimisation. There is an ongoing debate on the health effects of wind turbines, especially in terms of aerodynamic noise, coming from the rotational motion of the blades of these devices. Therefore, set-back distances have been reported globally in order to avoid or minimise possible criticisms or impacts from the population located nearby the turbines BIB003 . The noise coming from the wind turbine has been an issue for years which resulted in barrier to widespread the use of wind turbines BIB005 . It is one of the most typical obstacles to the application of wind turbines, it is necessary to design the wind turbine rotors as quiet as possible. Currently, there is limited work available to examine the sources of noise for these devices, in particular, smaller wind turbines. The noise can create a negative influence on people nearby wind turbine  . In addition, these devices can also have adversative impact on animals, specifically by collision with the turbine blades BIB011 . Large scale wind turbines were found to affect the local climatic conditions and the atmosphere, while smaller wind turbines can provide a good possibility for providing power that could be sufficient for local demands without changing the local conditions. The growing attention on the installation of sustainable energy systems has led to a wide range of micro-wind turbine methods introduced in the market. Though most of the commercially used wind turbines are the HAWT, vertical axis is recognised to have a potential technology for the future. The application of micro-small-scale wind turbine is increasing with also the legislation and support encouraging further development BIB006 . It is known that the environmental impacts produced in the operational process of wind turbines are lower compared to the ones produced by fossil fuels-based systems BIB001 , however, the overall contribution of smaller wind turbines may be limited. The environmental effects of small-micro turbines and their capability to contribute to climate change targets in the UK was examined by  . Installation of small wind turbines in the domestic sector would only save around 0.6-1% of greenhouse emissions of 2009. So, its potential to contribute to the climate change targets of the UK is limited. CFD modelling has been used by several researchers to predict the wind energy systems' performance over the last few decades. With the growing computing capacity of modern computers, CFD modelling has developed to a substantial tool to numerically assess the wind conditions within the investigated site or environment BIB012 BIB013 BIB014 . Current developments in wind turbine using CFD simulation have shown progress from flow modelling of flow around two-dimensional aerofoils to ABL or atmospheric boundary layer flow by arrangements of turbines or wind farms. The velocity profile of the wind depends on the boundary layer based on a complex terrain layout that varies significantly on the roughness of surface and local Reynolds number. Accuracy of CFD simulations of wind flow is important for choosing wind farm locations and the design of suitable wind turbines. The rising computational resource and power in the past few years permitted the CFD simulation of the sites containing the wind turbines. To respond to the challenges associated with the modelling of wind turbines in various scales, this study will review the state of the art and most recent literature (2010-2018) on the CFD modelling of wind turbine energy systems. Different types of wind turbine categories will be investigated: micro To respond to the challenges associated with the modelling of wind turbines in various scales, this study will review the state of the art and most recent literature (2010-2018) on the CFD modelling of wind turbine energy systems. Different types of wind turbine categories will be investigated: micro to small-scale, building mounted, and large-scale wind turbines based on the analysis of performance of these devices using CFD simulations. To identify articles for this review, a computerised literature search using terms such as "Wind Turbine", "Micro to Small Wind Turbine", "Building Mounted with Wind Turbine", "Wind Turbine installed in Wind Farm", and "CFD" in the Sciencedirect, Researchgate, and Springer database for publications available to date. These databases include scientific books, journals, articles, and papers from conference proceedings. Several publications were removed due to duplicates or unrelated to the CFD simulation. Moreover, only articles that were written in English were selected.