Urban Wind Power Research Articles

Assessment of urban wind energy resource in Hong Kong based on multi-instrument observations

Urban wind power is an appealing alternative for electricity supply. Comprehensive urban wind resource assessment is a prerequisite for cost-efficient deployment of wind turbines. Based on observations from multiple instruments, including a Doppler lidar (light detection and ranging) system, a microwave radiometer, and a cup anemometer/wind vane set, this study investigates the temporal (interannual, seasonal, and diurnal) variations of wind resources at various heights in a metropolitan city, Hong Kong. The long-term statistical distributions of wind speed, wind shear coefficient, and air density are analyzed, and their variations with height, wind direction, season, and time of day are thoroughly examined. Moreover, the wind power density and capacity factor of prototype wind turbines are estimated. It is observed that the statistical distributions of wind speed and air density are best represented by the Kappa and Normal-Weibull mixture distributions, respectively. There is a significant diurnal variation of wind shear coefficient, from 0.1 in the daytime to 0.4 at night. Moreover, a moderate potential for wind energy harvesting with wind power density of 110 W/m2 is found at the height of 120 m. This is the first known study that jointly uses lidar, microwave radiometer, and anemometer/wind vane for urban wind resource assessment. These instruments enable the investigation of the temporal variations of wind shear coefficient, air density, and wind power density at multiple heights, which were rarely examined in urban wind energy studies before.

Effect of wind-based climate-responsive design on city breathability of a compact high-rise city

As urban development advances, there is an increasing interest in compact cities as the most sustainable form. To suggest a pronounced connection between dense urban morphology and wind environments, this study adopts the new approach of wind-based climate-responsive design to investigate the influences of urban density, building corner modification, and wind direction on urban ventilation outcomes for the enhancement of city breathability. The airflow rates are estimated using a high-rise building array layout to optimize urban penetrability for enhancing breathability. The results of the CFD parametric study indicate that compact urban layouts with larger λp values experience good infiltration rates, ensuring wind comfort at the pedestrian level. Conversely, sparse urban forms with reduced λp values can achieve better permeation outcomes, resulting in elevated wind speeds at the middle level and near the roof of buildings, as well as higher airflow rates through the urban canyon layer. Additionally, the implementation of round corners reduces average wind speeds at the pedestrian level by 39% and increases wind speeds above the middle level of high-rise buildings by 20%, as compared to those of sharp corners. These findings offer valuable insights for high-rise building planning strategies, serving as both immediate and long-term solutions to realize the sustainable objectives of wind-based climate-responsive design in compact cities. Present research has offered the multifaceted trends of wind energy assessments on the realization of urban wind power. This paper also provides a theoretical framework that can assist urban designers in implementing the wind-based climate-responsive designs and enhancing living environments in contemporary compact cities.

Effect of void space arrangement on wind power potential and pressure coefficient distributions for high-rise void buildings

High-rise void building complexes can augment the permeation of airflows over buildings, and thereby strengthen urban wind energy harvesting for realization of the sustainable development goals (SDGs). This paper considers the wind over a typical 2×2 compact high-rise building array with the openings to analyze the wind power potential at varying void sizes, locations of voids, and direction of incoming wind. The predicted mean wind speeds and turbulence intensities are compared against the measured data with 4 generic high-rise building models having voids in an atmospheric boundary layer wind tunnel for validation of the computational model. Based on the comparative results from four common Reynolds-averaged Navier-Stokes (RANS) turbulence models including the standard, realizable, renormalization group (RNG) k-ε, and shear-stress transport (SST) k-ω models as well as the Reynolds stress model (RSM), the RSM approach can provide the most accurate predictions of streamwise mean velocity and turbulence intensity. The present study then conducts CFD simulations to explore the effects of opening configuration and wind direction on the wind field around high-rise void buildings. Considering the variations of void sizes of 10 × 10 m2, 12.5 × 12.5 m2, 15 × 15 m2, void heights of z/H = 0.25, 0.5, 0.75 and wind directions of 0°, 45°, respectively, the simulated results indicate elevated wind power densities with acceptable turbulence intensities over the upstream gap passage and void channels to achieve prospective urban wind power harvest and mitigate wind load on structures of high-rise void buildings.

Smart Urban Wind Power Forecasting: Integrating Weibull Distribution, Recurrent Neural Networks, and Numerical Weather Prediction

The design, operational planning, and integration of wind power plants with other renewables and the grid face challenges attributed to the intermittent nature of wind power generation. Addressing this issue necessitates the development of a smart wind power (and in particular wind speed) forecasting approach. This is a complex task due to substantial fluctuations in wind speed. To overcome the inherent stochastic nature of wind speed and mitigate related challenges, traditionally, numerical weather prediction (NWP) models are employed for wind speed forecasting. However, the applicability of NWP models is limited to short-term forecasting due to their computational constraints. In this study, a hybrid AI-based approach is proposed to improve forecast accuracy over a 48 h horizon for the city of Montreal. The results demonstrate that by integrating the probability distribution of wind speed with a deep learning model, the forecasted values align closely with the observed values in terms of seasonality and trend, exhibiting enhanced accuracy. Evaluation metrics reveal a substantial reduction in the root mean squared error (13–31%) across three prediction horizons (summer, fall, and winter) compared to a single long, short-term memory model. Furthermore, integrating the improved model with the numerical weather prediction model yields increased accuracy and decreased error compared to the LSTM–Weibull model.

Research on Safety Risk Assessment Method of Wind Power Enterprises Based on Hybrid Analytic Hierarchy Process

With the increase in urban demand for wind power, wind power has become one of the main energy sources for urban production and life. There are many hidden dangers of safety production in urban wind power enterprises in China. Therefore, it is particularly necessary to study the risk evaluation model of urban wind power enterprises. However, the previous evaluation methods seldom consider the impact of risk factors. Aiming at this problem, this paper proposes a fuzzy hybrid AHP evaluation method. Firstly, combined with AHP and network AHP, a hybrid hierarchical structure model of risk evaluation indicators is established, which improves the influence relationship between risk indicators in the index hierarchy model. Secondly, combined with the fuzzy evaluation method, the experimental analysis proves that the model has certain accuracy in the process of practical application.

Estimating Urban Wind Speeds and Wind Power Potentials Based on Machine Learning with City Fast Fluid Dynamics Training Data

Wind power is known as a major renewable and eco-friendly power generation source. As a clean and cost-effective energy source, wind power utilization has grown rapidly worldwide. A roof-mounted wind turbine is a wind power system that lowers energy transmission costs and benefits from wind power potential in urban areas. However, predicting wind power potential is a complex problem because of unpredictable wind patterns, particularly in urban areas. In this study, by using computational fluid dynamics (CFD) and the concept of nondimensionality, with the help of machine learning techniques, we demonstrate a new method for predicting the wind power potential of a cluster of roof-mounted wind turbines over an actual urban area in Montreal, Canada. CFD simulations are achieved using city fast fluid dynamics (CityFFD), developed for urban microclimate simulations. The random forest model trains data generated by CityFFD for wind prediction. The accuracy of CityFFD is investigated by modeling an actual urban area and comparing the numerical data with measured data from a local weather station. The proposed technique is demonstrated by estimating the wind power potential in the downtown area with more than 250 buildings for a long-term period (2020–2049).

Study on the operation of small rooftop wind turbines and its effect on the wind environment in blocks

Rooftop wind turbine is a typical utilization form of urban wind power. However, knowledge gaps still exist in the understanding on the wind resources of an urban district, the operation of small rooftop turbines and its effect on the block wind environment. To add new knowledge on this subject, the operation of rooftop wind turbines in an urban district is numerically studied via large-eddy simulation. The turbines are modeled by the actuator disk model and the urban district is represented by 16 idealized cube-shaped buildings. We find that flow above the urban district shows an obvious speedup due to the crowding-out effect of the urban district, and the turbulence intensity is dramatically enhanced. Above the first two rows of buildings, flow adjusts intensely and quickly evolves to a quasi-fully developed regime downstream. Due to the flow characteristics above the rooftop, the relative power increment of the rooftop turbines increases first and then decreases with the hub height, the power and the load fluctuations of the turbines are significantly aggrandized near the rooftop and diminished far away from the rooftop. For the small turbines investigated in this study, the impacts of small rooftop turbines on the wind environment are almost negligible in the blocks.

Effects of a rooftop wind turbine on the dispersion of air pollutant behind a cube-shaped building

The concentration distribution of urban air pollutants is closely related to people's health. As an important utilization form of urban wind power, rooftop wind turbines have been widely used in cities. The wake effect of the rooftop wind turbines will change the flow behind buildings and then affect the pollutant dispersion. To this end, the pollutant dispersion behind the building is studied via the computational fluid dynamics method. The actuator disk model and idealized cube are adopted to model the wind turbine and the building, respectively. The study shows that the rooftop wind turbine can reduce the pollutant mass fraction near the ground and the pedestrian level. Due to the wake effect of the rooftop wind turbine, the turbulent fluctuation behind the building is weakened, and the spanwise pollutant dispersion is suppressed. Besides, the rooftop wind turbine weakens the downwash movement of the building, which enhances the vertical pollutant dispersion.

Economic benefits assessment of urban wind power central heating demonstration project considering the quantification of environmental benefits: A case from northern China

Electric heating can effectively control the winter haze and promote renewable energy accommodation, which has significant environmental and social benefits. However, due to the low investment enthusiasm of heating enterprises, the government provides huge subsidies to maintain the operation of electric heating. Based on this background, the environmental benefits of electric heating projects are quantified, and the economic and environmental benefits of urban wind power central heating projects are analyzed and evaluated from the perspective of the life cycle. Then, taking a wind power central heating project in northern China as an example, a more comprehensive, scientific, and accurate evaluation of the wind power central heating project has been carried out. The results show that the electric heating project has great environmental benefits, but the direct economic benefits are poor, which is mainly caused by its high initial investment and high electricity price. Finally, specific suggestions are put forward for the poor economic efficiency of wind power central heating projects. The research results can provide a reference for further perfecting the transaction mechanism of wind power centralized heating, formulating clean heating development policies, and promoting the development of clean heating in northern China.

Numerical assessments of wind power potential and installation arrangements in realistic highly urbanized areas

Various wind resource assessment (WRA) methods have been applied to explore the feasibility of installing wind turbines for urban wind energy harvest. Nevertheless, there are only limited computational fluid dynamics (CFD) studies available to consider WRA around high-rise buildings in realistic urbanized areas. This paper presents a numerical assessment of urban wind energy potential, specifically pursuing to overcome the limitations of former studies by addressing the following points: i) conducting a large-scale wind power estimation by employing the meticulous topography in realistic compact high-rise urban area; ii) validating CFD simulations with the on-site measurements in two seasons; iii) obtaining the annual mean wind speed, wind power density and turbulence intensity between the existing high-rise building features, including building geometry, roof geometry, presence or absence of upstream obstacles, arrangements of integrated building complex and parallel high-rise buildings; iv) investigating the local installation locations of wind turbines and the distances from rooftop sidewalls or lowest mounting heights above rooftops with high power densities and acceptable turbulence intensities for wind energy harvest. The results of this wind resource assessment suggest an effective strategy of turbine installation for implementing urban wind power potential in a realistic compact high-rise urban area.

Study on interaction between the wind-turbine wake and the urban district model by large eddy simulation

Urban wind power shows a great potential and plays a significant role for a sustainable city. As a fundamental issue, the interaction between the wind-turbine wake and a building array is studied here via large eddy simulation. The standard actuator disc model is used to model the wind turbine, and 16 cube-shaped buildings are used to represent the urban district. It is found that due to the blocking effect of the downstream urban district, a high-pressure region is formed upstream, which dramatically changes the trajectory of the wind-turbine wake and results in a fast wake recovery. In addition, the wind-turbine wake suppresses the vertical momentum flux and thereby reduces the wind speed in the streamwise streets. At the top region of the urban block below the trajectory of the turbine wake, the turbulence intensity substantially increases at the entrance region of the building array, while the overall turbulence intensity is considerably reduced at the bottom of the block.

An Original Approach Combining CFD, Linearized Models, and Deformation of Trees for Urban Wind Power Assessment

Wind energy is relevant to self-sufficiency in urban areas, but the accuracy of wind assessment is a barrier to allowing wind energy development. The aim of this work is to test the performance of the Griggs-Putnam Index of Deformity of trees (G-PID) over urban areas as an alternative method for assessing wind conditions. G-PID has been widely used in open terrains, but this work is the first attempt to apply it in urban areas. The results were compared with CFD simulations (ENVI-met), and finally, with the linear model WAsP to inspect if deformed trees can offer acceptable wind power assessments. WAsP (meso-) and ENVI-met (micrometeorological model) showed similar results in a test area inside the University of Lisbon Campus. All trees showed a deformation with the wind direction (S and SE). The mean G-PID wind speed for all trees was 5.9 m/s. Comparing this to the ENVI-met simulations results (mean speed for all trees was 4.25 m/s) made it necessary to adapt the index to urban terrains by reducing each Index Deformation class by about ~2 m/s. Nevertheless, more investigation is needed, since this study is just a first approach to this integrated methodology. Also, tree species and characteristics were not taken into account. These questions should be addressed in future studies, because the deformation of trees depends also on the tree species and phytosanitary conditions.

Multiobjective Optimization Design of Small-Scale Wind Power Generator With Outer Rotor Based on Box–Behnken Design

In this paper, the finite-element method (FEM) based on 2-D numerical analysis was used for the basic design and characteristics analysis of a small-scale 3-kW wind power generator to which a permanent-magnet generator was applied. A prototype was manufactured, and a characteristics experiment was performed to verify the designed generator. In addition, the optimization design in order to satisfy required power of a generator while minimizing the cogging torque and the back electromotive force (EMF) total harmonic distribution (THD) on the basis of the designed initial model generator was conducted using the Box-Behnken design (BBD), which is a response surface method (RSM). The cogging torque, the back EMF THD, and the output power for each level of the design factors selected by the BBD were derived by the FEM based on 2-D numerical analysis. As a result, the optimal design model was derived in consideration of the RSA among each factor and the main effect and the interaction effects of each factor. This demonstrated the validity of the optimized design of the urban small-scale wind power generator design using the BBD.

Impact Wind Turbines Implementation in Municipalities in the Context of Sustainable Urbanism with Focus on Dynamic Pedestrian Comfort

The article, in the context of sustainable urbanism, reflects current tendencies of small urban wind power plants implementation into municipalities. There is an emphasis on wind as one of the aspects of architectural design and urbanism. Due to extensional interdisciplinarity of the examined phenomenon, the article captures a wider framework of the issue. The sustainability objectives in the creation of settlements - housing environment are emphasized. By the overview of wind turbines and selected research papers article demonstrates the current state of the subject. Yet the research points out that dynamic pedestrian comfort is not being taken into account and chosen geometries are not suitable. The article outlines visions and possibilities of implementation of small urban wind power plants while correctly using tools, techniques and qualitative and quantitative parameters.

Analysis of robust optimization for decentralized microgrid energy management under uncertainty

Abstract The present paper provides an extended analysis of a microgrid energy management framework based on Robust Optimization (RO). Uncertainties in wind power generation and energy consumption are described in the form of Prediction Intervals (PIs), estimated by a Non-dominated Sorting Genetic Algorithm (NSGA-II) – trained Neural Network (NN). The framework is tested and exemplified in a microgrid formed by a middle-size train station (TS) with integrated photovoltaic power production system (PV), an urban wind power plant (WPP) and a surrounding residential district (D). The system is described by Agent-Based Modelling (ABM): each stakeholder is modeled as an individual agent, which aims at a specific goal, either of decreasing its expenses from power purchasing or increasing its revenues from power selling. The aim of this paper is to identify which is the uncertainty level associated to the “extreme” conditions upon which robust management decisions perform better than a microgrid management based on expected values. This work shows how the probability of occurrence of some specific uncertain events, e.g., failures of electrical lines and electricity demand and price peaks, highly conditions the reliability and performance indicators of the microgrid under the two optimization approaches: (i) RO based on the PIs of the uncertain parameters and (ii) optimization based on expected values.

Urban wind power and the private sector: community benefits, social acceptance and public engagement

Given the ambitious government targets for renewable energy generation in the UK, there has been a push by government and industry towards various types and scales of Renewable Energy Technologies (RETs). This paper explores the implications of commercial urban wind projects for local communities, drawing on a case study of proposals by ASDA to construct wind turbines in two semi-urban locations in the UK. The paper argues that community responses to the proposals were complex and varied and could not adequately be encapsulated by ‘nimby’ (not in my back yard) assignations. It concludes that while ASDA followed a process of consulting local people, this process highlighted the problems of the ‘business as usual’ approach to public engagement employed by ASDA, and assumptions made about public acceptance of RETs.

Proposal and development of radial air‐gap coreless generator suitable for small wind turbine used in urban area

AbstractIndependent distributed power generation using small wind turbines is becoming more widespread as wind power generation increases. Installation of small wind turbines in densely populated urban areas is not only useful from the viewpoint of extracting wind power sources in weak‐wind areas but also for making renewable energy easier to access when power supplies are closer to consumers. It is from this point of view that the authors proposed “urban wind power generation” using a collective system with a number of small vertical wind turbines, and have developed a suitable generator for low‐speed vertical wind turbines such as a Savonius windmill.Based on a standard coreless generator, the proposed generator is designed to make the direction of the magnetic flux radial in order to install the magnets and coils on the outer end of the generator. The change of magnet composition and flux direction maximizes the speed of the flux change and output voltage within a limited space. With the above configuration, the power of the proposed generator is independent of the diameter.In this report, the authors describe and evaluate the fundamental performance of a prototype of the proposed generator. Based on the experiments, a maximum output power of 283 W was obtained. The obtained starting torque is small enough to begin rotation under weak wind conditions of no more than 1 m/s. Therefore, it is clear that the proposed “radial” coreless generator is suitable for self‐starting and producing high power at low wind speed. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(1): 26– 34, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20695

Urban wind energy conversion: The potential of ducted turbines

The prospects for urban wind power are discussed. A roof-mounted ducted wind turbine, which uses pressure differentials created by wind flow around a building, is proposed as an alternative to more conventional approaches. Outcomes from tests at model and prototype scale are described, and a simple mathematical model is presented. Predictions from the latter suggest that a ducted turbine can produce very high specific power outputs, going some way to offsetting its directional sensitivity. Further predictions using climate files are made to assess annual energy output and seasonal variations, with a conventional small wind turbine and a photovoltaic panel as comparators. It is concluded that ducted turbines have significant potential for retro-fitting to existing buildings, and have clear advantages where visual impact and safety are matters of concern.

502 都市型風力発電システムに関する研究 : クロスフロータービンの性能向上(1)(OS5-1 風力発電,OS5 風力発電,オーガナイズドセッション)

502 都市型風力発電システムに関する研究 : クロスフロータービンの性能向上(1)(OS5-1 風力発電,OS5 風力発電,オーガナイズドセッション)