Low Wind Speed Areas Research Articles

Thermal, Electrical, and Economic Performance of a Hybrid Solar-Wind-Geothermal System: Case Study of a Detached House in Hamburg and Sylt, Germany

Germany is undergoing an energy transition. By 2045, fossil fuels will be gradually replaced by clean energy. An alternative option is to use geothermal, solar and wind energy to generate heat or electricity. Currently, an economic model that considers these three energy sources and incorporates the design and installation of the energy system as well as operational costing focusing on the local market is lacking. In this study, we present a concept for a hybrid energy system combining solar, wind and geothermal energy for small, detached houses. We also develop a simplified economic model for the German market and local energy subsidy policies. The model was applied to two different cities in northern Germany, calculating the installation and long-term operating costs of different energy systems and combinations over a period of 100 years, including the consideration of the lifespan of variable equipment. The calculations show that for this small hybrid energy system the initial installation costs can vary from EUR 20,344 to EUR 70,186 depending on different portfolios. Long-term operating costs come mainly from electricity purchased from the grid to compensate for periods of low solar or wind production. In addition, the study included a calculation of the payback period for retrofitting a natural gas heating system. Results show that combining a photovoltaic system with a ground source heat pump, especially in the form of a near-surface heat exchanger, yields a shorter payback period (5 to 10 years). However, the incorporation of on-roof wind turbines into the hybrid energy system may significantly prolong the payback period and is therefore not recommended for use in low wind speed areas.

Site Selection for Offshore Wind Power Farms with Natural Disaster Risk Assessment: A Case Study of the Waters off Taiwan’s West Coast

This research examines the risk of natural disasters for offshore wind turbines together with their potential wind energy capacity to help the site selection of offshore wind power farms. Through evaluations of expert questionnaires, we use the fuzzy analytic hierarchy process to weight how natural disasters damage the sub-assemblies of an offshore wind turbine, then obtain the natural disaster risk assessment model, and finally utilize ArcGIS Pro 3.2 to map the potential wind farm sites for the waters off Taiwan’s west coast. We identify that typhoons are the most threatening type of disaster to generators, rotor blades, and rotor hubs; earthquakes are the most threatening to towers; and lightning is the most threatening to transformers. For the whole wind turbine, wind is ironically the most threatening natural disaster, followed by lightning, sea waves, and then earthquakes. Lastly, we examine the results by overlapping the offshore wind farms developed and planned in Taiwan, which coincide with locations in relatively low risk and high wind speed areas.

Integrated energy system scheduling optimization considering vertical-axis wind turbines and thermal inertia in oilfield management areas

Traditional horizontal-axis wind turbines (HAWTs) have limited efficiency in low-wind speed regions. In this paper, an integrated energy system (IES) incorporating vertical-axis wind turbines (VAWTs) is proposed; this IES is located in an oilfield management area, which can utilize the low-wind speed resources more efficiently and improve renewable energy consumption, and it also introduces a demand response model based on thermal inertia (TI), thus smoothing out the volatility caused by the VAWT. Typical output scenarios are obtained through stochastic optimization to deal with wind turbine and photovoltaic output uncertainties, and an optimal scheduling model is proposed to minimize the system operating cost. Finally, a simulation study was conducted in a micro-oilfield management area in Shandong Province, China, to demonstrate the performance of the proposed system. The results show that the IES using a VAWT and TI can increase the renewable energy consumption capacity by 87% over the conventional HAWT system, change the user behavior, increase the economic efficiency by 12%, and achieve the smoothing of load-side fluctuation of electric and thermal loads, peak shaving, and valley filling. This paper provides a feasible solution for an IES in low-wind speed areas.

Wind speed prediction for site selection and reliable operation of wind power plants in coastal regions using machine learning algorithm variants

The challenge of predicting wind speeds to facilitate site selection and the consistent operation of wind power plants in coastal regions is a global concern. The output of wind turbines is subject to fluctuations corresponding to changes in wind speed. The unpredictable characteristics of wind patterns introduce vulnerabilities to wind power facilities in wind power plants. To address this unpredictability, an effective strategy involves forecasting wind speeds at specific locations during wind power plant operations. While previous research has explored various machine learning algorithms to tackle these issues, satisfactory results have not been achieved, and Bangladesh faces challenges in this regard, especially in low-wind speed areas. This study aims to identify the most accurate machine learning-based algorithm to forecast the short-term wind speed of two areas (Kutubdia and Cox's Bazar) located on the eastern coast of Bangladesh. Wind speed data for a span of 21.5 years, ranging from January 2001 to June 2022, were sourced from two outlets: the Bangladesh Meteorological Department and the website of NASA. Wind speed has been forecasted using 14 different regression-based machine learning models with a comprehensive overview. The results of the experiment highlight the exceptional predictive performance of a boosting-based ensemble method known as categorical boosting, especially in the context of forecasting wind speed data obtained from NASA. Based on the testing data, the evaluation yields remarkable results, with coefficients of determination measuring 0.8621 and 0.8758 for wind speed in Kutubdia and Cox's Bazar, respectively. The study underscores the critical importance of prioritizing optimal turbine site selection in the context of wind power facilities in Bangladesh. This approach can yield benefits for stakeholders, including engineers and project owners associated with wind projects.

Integrated fatigue assessment method considering average stress effects of large-scale lattice wind turbine support structures

Modular assembly techniques for ultra-high lattice wind turbine support structures are gaining popularity as a viable solution for wind energy development in low wind speed areas. However, efficient fatigue assessment of the overall structure is crucial for the widespread promotion and application of these structures. Existing engineering methods for fatigue assessment suffer from limitations in calculation efficiency and often fail to account for the effects of average stress. To address these issues, a novel integrated fatigue assessment method is proposed, which is both fast and efficient while considering the impact of average stress. The method enables the computation of cumulative fatigue damage and fatigue life for each component, as well as the identification of the location of the greatest cumulative fatigue damage in the structure. An onshore ultra-high lattice wind turbine support structure, modularly assembled to a height of 180 m, is utilized as an application example to illustrate the specific implementation process of the proposed method. The effect of different fatigue load conditions and transfer functions on cumulative fatigue damage is analyzed, and the relationship between transfer function and fatigue accumulation damage is examined. The findings indicate that average stress plays a crucial role in the cumulative fatigue damage of ultra-high lattice wind turbine support structures, and the proposed integrated fatigue assessment method simplifies the calculation process for fatigue-resistant designs substantially.

Modelling and analysis of jute fiber reinforced epoxy composite in the development of wind blade for low intensity winds

Natural fibers show an increasing potential as reinforcement of polymeric composites, representing a promising concurrent to glass and carbon fibers extensively used in the construction of wind turbine blades synthetic fibers recyclability/disposability and high production energy cost have already been discussed in the main turbine producing centres. In particular, the development of wind turbines for low wind speed areas can increase the energy generation potential of regions not originally eligible for the installation of large turbines. This study proposes the evaluation of the use of jute fiber (Corchorus capsularis) reinforced epoxy composite in the construction of S1210 airfoil profile, of a small-scale wind turbine for low wind speed regions, considering the structural parameters, developed incorporating the Classical Laminate Theory (CLT) and Extended Bredt-Batho Shear Flow Theory (EBSFT).In order to raise the elastic properties and enable the use of the failure criteria, the composite blades were characterized according to ASTM standards. The mechanical properties surveyed, together with the elastic parameters of the cross section, torsional stiffness, axial stiffness, GJ 1873.6 N m2, EI 9.47 × 104 N m2, and flexural rigidity, Ely 4.97 × 104 N m2, Elz 1.45 × 106 N m2, respectively, demonstrated the feasibility of using the jute fiber reinforced epoxy composite in the blade construction, evaluated according to the maximum tension failure criterion.

Technical and performance assessments of wind turbines in low wind speed areas using numerical, metaheuristic and remote sensing procedures

The application of innovative technologies in the manufacture of wind turbines (WT) has produced more efficient WT that can operate successfully in low wind speed (LWS) environments. This technology has not been implemented in many LWS parts of the world due to the paucity of enabling technical information (wind resource availability and wind turbine configuration). This study uses ten years wind speed data from twelve Nigerian cities and their population densities, remote sensing, and the configuration of some commercially available LWS turbines in generating technical information suitable for data-backed decision-making on low-speed turbine deployability, operational conditions, and energy yield at 50 and 400 m. Five different numerical and metaheuristic procedures were randomly selected and utilized to estimate Weibull parameters used in computing wind energy development (WEDP) parameters (effective wind power density, EWPD, and wind available time). WT with low cut-in speeds (∼2 m.s−1) can be installed in all the cities. With the highest EWPD and WEDP ratings (100%) at both 50 and 400 m, Obudu is the most suitable location for the development of wind power infrastructure.

An Improved Optimal Tracking Rotor Algorithm of Wind Turbine Based on Dynamic Adjustment of Compensation Coefficient

The Optimal Tracking Rotor method, as one of the control methods for MPPT, increases the compensation coefficient to achieve an improvement in average wind energy capture efficiency, but it causes a significant increase in wind turbine load. There are differences in the energy contained between the high-wind-speed areas and the low-wind-speed areas. This paper proposes an improved optimal tracking rotor method by dynamically adjusting the compensation coefficient, to enhance the capture of wind energy in high wind speed areas and slow down the capture of wind energy in low wind speed areas. After research, it was found that the adjustment of the compensation coefficient varies with changes in wind speed and wind wheel acceleration. In response to this problem, the optimal change curve between the compensation coefficient and related parameters was determined. Fuzzy control was used to achieve dynamic adjustment of the compensation coefficient. Finally, the effectiveness of the proposed method was verified based on simulation results in Matlab/Simulink.

Numerical Investigation of Hybrid Savonius-Darrieus Vertical Axis Wind Turbine at Low Wind Speeds

The need for electricity on the Earth is increasing day by day, and this requires building more electric power plants where most of the power plants cause CO2 emission which would increase the global warming. Using wind energy as one type of renewable energies, would contribute to reduce the global warming. In countries such as Malaysia where the average annual wind speed is 2-2.5 m/s using wind energy is a challenge because of the low wind speed. However, using a hybrid Savonius-Darrieus vertical axis wind turbine in low wind speed areas, the performance of the wind turbine may increase, and the starting rotation speed will decrease. This research aims at a comprehensive study on a hybrid Savonius-Darrieus wind turbine with helical Savonius rotor combined with helical and straight bladed Darrieus rotor. In this research, a base model with the name of Model Base was generated and two models with new configurations were generated in SOLIDWORKS. A numerical studies and simulation were conducted on these three designs using Ansys Fluent to identify the more suitable combination for low wind speed areas. Based on the obtained result hybrid Savonius-Darrieus with helical Savonius rotor and helical Darrieus rotor were found to be the most suitable combination because of their stable aerodynamic performance throughout a full rotation. Best performance for these models was found to be at 0.45 TRS with maximum torque and power coefficients of 0.68 and 0.306 respectively.

A unified optimization control of wind farms considering wake effect for grid frequency support

This paper proposed a unified active power optimization control of wind farms under wake effect. It takes the sum of the kinetic energy variation and pitch angle variation as the optimization objective and used the particle swarm algorithm to achieve the optimization results. The main feature of the proposed method is that it unifies the kinetic energy optimization under a low wind speed area, the pitch angle and kinetic energy trade-off optimization under a medium wind speed area, and the pitch angle optimization under a high wind speed area. Combined with the de-loaded power constraint, it can flexibly reach various optimal operating states of the wind farm. The simulation results show that the proposed method optimizes the rotor speed and pitch angle in different wind speed areas, and releases kinetic energy and/or increases the output power of the wind farm to provide frequency support by switching the operating states.

Improving the self-starting and operating characteristics of vertical axis wind turbine by changing center distance in part of blades

Compared with the horizontal axis wind turbine (HAWT), the vertical axis wind turbine (VAWT) has the advantages of low noise operation and no wind yaw device. However, the poor self-starting performance of VAWT is one of key problems restricting its development. In order to improve the self-starting capability of VAWTs in urban wind areas, this paper proposed a VAWT model with multi-blade local variable radius. The main object of this study is to research the effect of reducing the partial blade radius on the self-starting performance and power coefficient of the VAWT. In this study, the partial blade radius of the VAWT models was reduced to 0.375, 0.5, and 0.625 times of the outer layer. The dynamic torques and velocity contours of the different models were researched by experiments and numerical simulations to analyze the reason why reducing the partial blade radius affects the power coefficient of the VAWT. The static torque and static pressure contours of different models were researched to compare the self-starting capability of the models. According to the results, the minimum static torque values of the three innovative VAWT models were increased by 0.1, 1.8, and 2.8 times, respectively, compared to the traditional VAWT with only the outer layer. Furthermore, the power coefficients of three models were increased for tip speed ratios (TSR) less than 2.2. Therefore, the new models can improve the self-starting capability of VAWTs, and the higher power coefficients at low TSRs make them more advantageous for applications in urban buildings and low wind speed areas.

Numerical Investigation of the Power Performance of the Vertical-Axis Wind Turbine with Endplates

An H-rotor vertical axis wind turbine (VAWTs) can operate independently in any wind direction, making it aerodynamically efficient and suitable to harness wind energy in low wind speed areas. The aerodynamic efficiency of VAWTs is highly dependent on the blade geometry, especially the blade tip. Tip vortices produced at the blade tips can negatively affect the VAWT’s aerodynamic efficiency. Adding endplates to the blade tips can minimize the effects of tip vortices on VAWTs. In this paper, several endplate designs are used to evaluate the effectiveness in improving the power coefficient, Cp of a VAWT at three different tip speed ratios (TSRs) using three-dimensional computational fluid dynamics (3D CFD) simulation. The power coefficients of VAWTs with endplates are compared with the baseline model with the same geometrical parameters where the baseline VAWT model is based on the experimental model from the literature. Since the focus of this study is on the blade tip design, a simplified 3D VAWT model is used where the supporting shaft and arms of the VAWT are excluded to reduce the needed computational capacity. Among the various endplate designs used in this study, the semi-circular inward endplate (ED3) with a diameter equivalent to 1.2 blade chord length showed the best improvement in the Cp which is by 7.45%, and 5.79% for at the TSRs of 2.19 and 2.58, respectively. The pressure difference on both sides of the blade was also examined. The results revealed that the endplate can prevent the flow from bypassing the blade tip, hence, preventing the occurrence of tip vortices while improving the aerodynamic efficiency near the blade tip, ultimately, improving the overall Cp of a VAWT.

Experimentation of helical flow path in an augmented wind turbine

The design of wind turbine blade for low wind speed area is historically experimented by many researchers and gives us different results with nearly same parameters. Also, augmentation of wind turbine improves power generation capacity in magnified manner. This paper deals with the fabrication and investigation of augmented wind turbine specially prepared with helical flow path. The experimentationdonewithcombinationofdifferentparameterssuchaswindspeed, pitch distance and angle of attack of wind flow.

Investigation of Snow Deposition on the Railway Cuttings During the Snowdrift

This study confirmed a mixture multiphase model based on the Euler–Euler method to predict snow deposition in road cuttings. A scaled model experiment was conducted in the Mayitas region of Xinjiang to verify the numerical simulation accuracy, which revealed a good agreement. Regarding the formation mechanism of drifting snow disasters in road cuttings, the wind speed in the simulation results was analyzed in detail. The results indicated that the low-wind speed area is positively correlated with the vortex size and that snow deposition occurs between the vortex separation point and vortex reattachment point. The appearance and disappearance of the secondary vortex can divide the snow cover process into three stages, and the second phase after secondary vortex emergence represents the period of a rapid increase in the snow thickness. Snow cornices are the leading emergence cause of secondary vortex. The related critical snow storage capacity should also be considered to measure the snow storage capacity of road cutting types.

Design and Optimization of a Small-Scale Horizontal Axis Wind Turbine Blade for Energy Harvesting at Low Wind Profile Areas

Wind turbine blades perform the most important function in the wind energy conversion process. It plays the most vital role of absorbing the kinetic energy of the wind, and converting it to mechanical energy before it is transformed into electrical energy by generators. In this work, National Advisory Committee for Aeronautics (NACA) 4412 and SG6043 airfoils were selected to design a small horizontal axis variable speed wind turbine blade for harvesting efficient energy from low wind speed areas. Due to the low wind profile of the targeted area, a blade of one-meter radius was considered in this study. To attain the set objectives of fast starting time and generate more torque and power at low wind speeds, optimization was carryout by varying Reynolds numbers (Re) on tip speed ratios (TSR) values of 4, 5, and 6. The blade element momentum (BEM) method was developed in MATLAB programming code to iteratively find the best twist and chord distributions along the one-meter blade length for each Re and tip speed ratio (TSR) value. To further enhance the blade performance, the twist and chord distributions were transferred to Q-blade software, where simulations of the power coefficients (Cp) were performed and further optimized by varying the angles of attack. The highest power coefficients values of 0.42, 0.43, and 0.44 were recorded with NACA 4412 rotor blades, and 0.43, 0.44, and 0.45 with SG6043 rotor blades. At the Re of 3.0 × 105, the blades were able to harvest maximum power of 144.73 watts (W), 159.69 W, and 201.04 W with the NACA 4412 and 213.15 W, 226.44 W, 245.09 W with the SG6043 at the TSR of 4, 5, and 6 respectively. The lowest cut-in speed of 1.80 m/s and 1.70 m/s were achieved with NACA 4412 and SG6043 airfoils at TSR 4. At a low wind speed of 4 m/s, the blades were able to harness an efficient power of 79.3. W and 80.10 W with both rotor blades at the TSR 4 and 6 accordingly.

Influence of Axial Distance and Duct Angle in the Improvement of Power Generation in Duct Augmented Wind Turbines

Abstract Diffuser augmented wind turbines (DAWTs) are incredibly beneficial to low wind speed areas. The duct that surrounds the turbine improves the power output by accelerating the approaching wind directing the wind through the blade. The power output of DAWT mainly depends on the duct length by turbine diameter (L/D) ratio, duct angle, axial distance, and tip clearance between the blade and duct. This article gives an insight into the performance variation of DAWT for various duct L/D ratios. Numerical simulations were performed on DAWT using ansys fluent, and the performance characteristics were studied for different duct L/D ratios, duct angles, and axial distance. The investigations found that axial distance of 0.06D for duct L/D ratios between 0.15 and 0.60 gives improved performance. It was found that the optimal duct angle is a function of the L/D ratio, and as the L/D ratio increases, the duct angle increases. A geometric procedure was used to find the pattern in which the angle increases in other L/D ratios. The geometric procedure helps to keep the duct’s inner profiles merging for duct L/D ratios 0.15 to 0.6 by maintaining constant axial distance. By keeping the ducts as per the proposed procedure resulted in angles 22 deg, 38 deg, 45 deg, and 52 deg for duct L/D = 0.15, 0.3, 0.45, and 0.6. The performance of WT with 30 deg angled ducts and proposed angled ducts was compared. The proposed angled ducts had improved power output than 30 deg angled ducts. The proposed axial distance and duct angles help to use the duct length effectively, which shortens the duct and enhances power output.

An Analysis of Elevated Building Design on Building Surrounded Outdoor Wind Environment

Building elevated design is one of the methods that may improve the outdoor wind environment. Integrating computational fluid dynamics (CFD) simulation into an architectural design can provide an informed decision for architectural design. In this study, CFD simulation was used to explore elevated design impacts on a case study building wind environment at the building’s pedestrian height. Simulation results from two CFD programs were compared and both showed that the elevated design of the case study building had a good effect on improving the wind environment at the pedestrian height of 1.5 m. The elevated design can increase the wind speed of the 1.5 m pedestrian height in the building’s windward area when the elevated height is 2.4～3.0 m. When the elevated design height is above 3.0 m, the elevated design has little impact on the 1.5 m height wind speed at the building’s windward area. Taking the case study building as a prototype, the impact of various building heights and elevated widths on the pedestrian height outdoor wind speeds were explored. Results show that when the building height is between 24 and 72 m, increasing the building height can increase the wind speeds of at pedestrian height in the high wind speed area of the windward area, but may gradually reduce the wind speed at the pedestrian height in the low wind speed area of the windward area around the building. When the total height of the building and the elevated height is unchanged, results show that increasing the elevated width of the building can increase the pedestrian height wind speeds in the high wind speed area of the windward area and has no significant impacts on the pedestrian height wind field distribution in the low wind speed area of the windward area.

SENSITIVITY ANALYSIS OF ANGLE, LENGTH AND BRIM HEIGHT OF THE DIFFUSER FOR THE SMALL DIFFUSER AUGMENTED WIND TURBIN

This paper presents the performance of the diffuser augmented wind turbine (DAWT) with the various diffuser shapes using the numerical investigations. DAWT is also a type of wind turbine and the diffuser shapes, the nozzle shapes and the cylindrical shapes are commonly inserted around the horizontal axis wind turbine (HAWT) to become the more efficient wind turbine. The aim of this study is to find the more efficient design of the diffuser for the horizontal axis wind turbine using the numerical investigations. In this research, the converging and diverging diffuser shape is inserted and the airfoil design is calculated by using the Blade Elementary Momentum Theory. The airfoil type NACA 4412 is chosen because it is suitable for the low wind speed area and easy to produce. The turbulent model k-ω is combined with the Navier Stoke equation to solve the 3-dimensional steady flow simulation of the diffuser augmented wind turbine using the Computational Fluid Dynamics (CFD) simulations. The numerical investigation is used to compare and predict the power coefficient of the DAWT with various shapes. The baseline design of the diffuser (L = 170 mm, H = 57 mm and α = 11̊) is firstly investigated. To predict the power coefficient of the various diffuser shapes, the range of the length of the diffuser is (L/D = 0.5 to 1.5), the range of the brim height of the diffuser (H/D = 0.1 to 0.35) and the range of the angle of the diffuser (α = 5̊ to 15̊ ) are also investigated. The parameters of the diffuser shapes are assigned by using the Central Composite Design Face Centered Method. The response surface method is also used to predict the most efficient diffuser design. The performance of the horizontal axis wind turbine, that of the diffuser augmented wind turbine and that of the diffuser augmented wind turbine with various shapes of diffuser are compared. The performance of new diffuser augmented wind turbine (IND_009) is 50% and 55% higher than the baseline diffuser augmented wind turbine and the horizontal axis wind turbine at rated velocity. The flow visualization of the HAWT, DAWTs are also discussed.

Influence of noise barrier and louver on ventilation and thermal performance of wet cooling towers under crosswind conditions

Aiming at the influence of noise barrier and louver on the thermal performance of wet cooling towers, a three-dimensional numerical model of wet cooling towers was established in this paper. Based on this model, the influence of the noise barrier and louver on ventilation and thermal performance was studied under crosswind conditions (crosswind velocity varies from 0 m/s to 10 m/s and crosswind direction α is 0°, 90°, 180°). To analyze the influence of noise barrier and louver on the air intake characteristics, the inlet air uniformity coefficient Cff and the effective inlet air velocity vave were defined. Simulation results manifested that the noise barrier increases the internal low wind speed area in the rain zone and the high water temperature area on the collecting basin surface. Compared with the original cooling tower, although the Cff increases, the vave and the cooling capacity contribution of the fillings zone CF decrease after installing the noise barrier, so the water temperature drop ΔTW decreases. Additionally, the louver can relieve the adverse effect of crosswind on thermal performance, and the Cff, vave, CF, and ΔTW all have an increasing trend under crosswind conditions after installing the louver. The louver can improve remarkably the thermal performance when the crosswind velocity is 6 m/s and α = 90°, and compared with the original cooling tower, the Cff, vave, CF, and ΔTW increase by 0.02, 1.33 m/s, 1.33%, 0.31 °C, respectively.

Wind Energy Collection System Based on Phase Change System and Deformable Materials

The purpose of this paper is to design and discover a new system, which can realize the collection, transformation and storage of energy from wind energy in the environment ^ temperature/physical deformation → material phase change → energy storage, so as to achieve the effect of green energy saving. At the same time, it can provide theoretical support and design basis for the design of high-rise Garden residential suite in cold region. Wind energy is collected through the narrow channel effect. With the help of deformation induced ferrite phase transformation technology and memory alloy materials, the collected energy is stored in the new colloid/graphene battery equipment. With the help of the relevant content research parameters, a systematic digital model is formed, and the basic database is established to simulate the external environment of high-rise Garden residential buildings in cold areas. Through the design of a new wind energy collection system and embedded in the simulation environment, the wind energy utilization in cold, low sunshine, low wind speed or unstable wind speed areas is realized, and the green energy conservation, environmental protection and sustainable development in such areas are realized. Then, the feasibility and effectiveness of the system are demonstrated according to the experimental results, and a systematic theory is formed.