Wind Energy Harvesting Research Articles

Parameter effects on performance of piezoelectric wind energy harvesters based on the interaction between vortex-induced vibration and galloping

Our previous research experimentally validated that the interaction between vortex-induced vibration and galloping is an effective method for enhancing the performance of piezoelectric wind energy harvesters under low wind speed conditions. We proposed a distributed-parameter electromechanical coupling model as well. This study aims to investigate the effects of various parameters and optimize the performance of VIV-galloping interactive piezoelectric wind energy harvesters. Initially, we assessed the applicability of the model under different circuit and aerodynamic force conditions and discussed boundary and convergence conditions by replicating previous results. Further, simulations were performed to analyze the effects of the structural parameters of the bluff body and piezoelectric beam. The width or depth of the bluff body significantly influenced the low critical wind speed, interactive occurrence, and electrical output. To achieve a balance between material cost and electrical benefit, we recommend positioning the electrode length from the fixed end with a coverage ratio of at least 60%. Additionally, the output power is highly sensitive to the piezoelectric beam length, but reducing it results in a higher natural frequency and critical wind speed. We fabricated and tested four prototypes, which have demonstrated significantly higher power densities compared with previously reported values at the same wind speed.

Flow characteristics over flat building roof with different edge configurations for wind energy harvesting: A wind tunnel study

The impact of climate change and global warming makes it imperative to seek sustainable solutions for the built environment. To facilitate the design of future sustainable buildings, wind tunnel tests are conducted in this study to investigate the flow characteristics and wind energy potential over a flat building roof with different edge configurations. Specifically, this study addresses the effect of parapet walls and roof edge-mounted solar panels on the wind flow over a flat-roof tall building. The results show that parapet walls generally slow down the wind speed and increase turbulence intensity as well as skewness angle, which compromises the efficiency of traditional turbine-based wind energy harvesting. On the other hand, the presence of solar panels on the roof edge (or on the top of the parapet wall) further alters flow separation and has the potential to enhance wind energy harvesting over the roof, especially for the solar panel inclined at 30°. In addition to providing valuable data for validating computational fluid dynamics (CFD) simulations, this study could also help to guide the design of wind energy harvesting devices on the building roof and explore the promising synergy with solar panels.

Magnetic transfer piezoelectric wind energy harvester with dual vibration mode conversion

Wind-induced vibration piezoelectric energy harvesters have garnered significant interest in recent years as a means to power autonomous wireless sensor systems. A magnetic transfer piezoelectric wind energy harvester (MT-PWEH) is proposed and its durability, power generation performance and environmental adaptability are improved utilizing dual mode conversion. This MT-PWEH incorporated a downstream rectangular baffle, which facilitated the transition of the hollow cylinder from a traditional single vortex-induced vibration to a coupled vibration involving both vortex-induced vibration and galloping (i.e., the first vibration mode conversion). Besides, the vibration direction of the hollow cylinder was perpendicular to the vibration direction of the transducer, which achieved the purpose of limiting the amplitude (i.e., the second vibration mode conversion). The feasibility of MT-PWEH was confirmed through theoretical analysis, CFD simulation, fabrication and experiments. The experimental results demonstrated that the working characteristics of MT-PWEH were significantly affected by position and size of the baffle. Specifically, the ratio of the maximum cut-in wind speed of 12.5 m/s to the minimum cut-in wind speed of 1.2 m/s reached 10.4. Additionally, a maximum power output of 0.78 mW was recorded at 10 m/s with an optimal load resistance of 800 kΩ and 10 LEDs were drove successfully.

The Advancement of Artificial Intelligence's Application in Hybrid Solar and Wind Power Plant Optimization: A Study of the Literature

The harnessing of solar, wind, and hydroelectric energy sources has rendered them easily accessible renewable resources, owing to their abundant availability. There is a growing body of research evincing interest in the deployment of hybrid renewable energy systems. Over recent decades, adopting hybrid technologies has engendered a positive trend, marked by broader considerations of configurations and applications within these systems. This study analytically examines the potential of hybrid solar and wind energy harvesting devices. As such, the project aims to extensively evaluate relevant literature and statistical analysis of data extracted from journal papers published between 2004 and 2023. A specific objective is to develop a complete database matrix surrounding multiple categories, including component configurations, methodological approaches, and supporting software infrastructures. Moreover, an assessment of the socio-economic, environmental, and ecological impacts of these systems is undertaken to ascertain their salience. Furthermore, this inquiry delves into the optimization strategies of these systems leveraging artificial intelligence methodologies. Critical lacunae identified during this review pertain to more emphasis on optimization metrics for PV-wind hybrid energy systems, impeding a holistic understanding of their implications on energy, economics, environment, and society. Our findings underscore prevalent methodologies such as computational modelling utilizing software suites like MATLAB/Simulink, HOMER, and others to derive empirical data. Additionally, parametric analyses emerge as the predominant approach, characterized by the application of algorithms such as Particle Swarm Optimization (PSO), Fuzzy Logic Control (FLC), and Genetic Algorithms (GA), among others. PV-wind hybrid energy systems are classified into autonomous and grid-interconnected configurations, with primary components comprising PV-wind generators. The anticipated trajectory suggests a burgeoning development of these hybrid energy harvesting systems, underpinned by their potential as clean, sustainable, and eco-friendly energy sources.

Enhancing energy harvesting through hybrid bluff body at a predefined angle of attack coupling vortex-induced vibration and galloping

This paper introduces a novel approach to enhance energy harvesting efficiency by coupling vortex-induced vibration and galloping through the use of a D-shaped hybrid bluff body with a predefined angle of attack. By adjusting the angle of attack, the aerodynamic interaction with the bluff body is improved, significantly increasing the vibration amplitude. Wind tunnel experiments are conducted to explore the effects of the predefined angle of attack and the rectangular height of the bluff body cross-section on the energy harvester's efficiency. The analysis identifies several optimal configurations that utilize the coupled vortex-induced vibration and galloping to enhance energy harvesting at low wind speeds while maintaining significant vibration amplitudes at high wind speeds. The proposed structure could achieve an RMS output voltage of 38.76 V, representing a 153.5% improvement compared to the traditional galloping piezoelectric energy harvesters. Additionally, the cut-in wind speed is reduced by 37.5%, allowing vibrations to begin at a low wind speed of 1.5 m/s, exhibiting a superior wind energy harvesting efficiency. Two-dimensional computational fluid dynamics simulations are employed to explain the underlying mechanisms of fluid-structure interaction, demonstrating the characteristics of the flow field, vortex shedding, and the transition in vibration modes.

Study on dynamics and power generation performance coupling of galloping-based triboelectric nanogenerator for harvesting broadband wind energy

In order to innovate the wind energy harvesting method based on galloping and improve galloping-based triboelectric nanogenerator wind energy harvesting performance, a galloping-based square cylinder triboelectric nanogenerator (GSC-TENG) is proposed in this work. The GSC-TENG consists of a square cylinder bluff body, a triboelectrification embedded in the bluff body, a cantilever beam and a base. The response of the aerodynamics and power generation performance of the GSC-TENG with a high mass ratio (m*=526.6) to the system damping ratio (0.0106, 0.0304 and 0.0568) and wind speed (0.6–12.4 m/s) are studied through CFD simulation and wind tunnel test. The critical wind speed, amplitude and power generation performance of systems with different damping ratios are analyzed in detail, and the wind speed range corresponding to the maximum amplitude is determined. By increasing the stiffness and damping ratio of the system, the output performance under high wind speed conditions can be enhanced and stabilized. Compared with the GSC-TENG with damping ratio 0.0106, the output power of the GSC-TENG with damping ratio 0.0568 at the wind speed of 4.0 m/s is enhanced by 141 times, which is up to 62.25 W/m3. To harness a broadband wind energy, a novel galloping-based TENG is introduced. Analyzing the dynamic characteristics of square cylinder bluff body with different damping ratios is of significant meaning to the design and improve of the galloping-based triboelectric wind energy harvester.

Design and Characteristic Analysis of a Performance-Enhanced Piezoelectric Wind Energy Harvester With a Transformable Y-Type Bluff Body

Design and Characteristic Analysis of a Performance-Enhanced Piezoelectric Wind Energy Harvester With a Transformable Y-Type Bluff Body

An Endurable Triboelectric Nanogenerator for Wind Energy Harvesting Based on Centrifugal Force Induced Automatic Switching between Sliding and Rolling Modes

An Endurable Triboelectric Nanogenerator for Wind Energy Harvesting Based on Centrifugal Force Induced Automatic Switching between Sliding and Rolling Modes

Integrated Triboelectric Nanogenerator for Energy Harvesting: Efficient Absorption of Wind in 6–16 m s−1 Velocity Range and Wave Energy

The ocean harbors an abundance of resources, encompassing not only wave energy but also considerable wind energy. Triboelectric nanogenerator (TENG), as a technology for harvesting low‐frequency, high‐entropy mechanical energy, has shown distinct advantages in the collection and application of marine and wind energy. This study introduces a triboelectric Wind and wave energy harvester (TWWEH), an energy collector based on TENG, which can be used to harness wind and wave energy. The TWWEHs comprise a wind‐driven TENG (W‐TENG) for wind energy collection and a ring‐shaped TENG (R‐TENG) for wave energy collection. The proposed vertically integrated TENG architecture enhances spatial utilization rate. Under oscillatory conditions of 0.8 Hz and ±30°, the R‐TENG generates a peak power of 0.20 mW. While at a wind speed of 10 m s−1, a peak power of the W‐TENG can reach 0.11 mW. This research provides a promising solution to harvest wave and wind energy from the ocean, offering significant potential applications in establishing self‐powered oceanic assessment and meteorological systems.

Exploring the influence of concave-convex surface modifications on piezoelectric wind energy harvesting: A numerical analysis

Wireless health monitoring sensors are significant for the safety of sea-crossing bridges, and their operation is dependent on a durable and reliable power source. Piezoelectric wind energy harvesters (PWEHs) can be effectively utilized in windy marine environments and provide a sustainable power supply for these sensors. This paper examines the influence of concave-convex surface modifications of a circular cylinder on the performance of the PWEH through numerical research to improve the output and operational bandwidth of traditional harvesters using cylindrical bluff bodies. An electromechanical model, coupled with computational fluid dynamics on low-Reynolds-number flows, was developed and different concave-convex configurations were proposed to explore the impact by numerical experiments. The results show that the configuration with two protrusions plus one groove is the optimal design. This configuration exhibits a much higher output with a maximum voltage of 19.5 V, representing a 464% increase compared to the cylindrical bluff body's 4.2 V, and a broader bandwidth with no upper limit across the wind speed range. This study provides insight into effective and ineffective efforts to enhance energy harvesting through concave-convex surface modifications and is advantageous to the advancement of self-powered marine sensing systems, particularly in the health monitoring of sea-crossing bridges.

Flexible self-powered triboelectric nanogenerator sensor for wind speed measurement driven by moving trains

Flexible self-powered sensors have been extensively applied to the Internet of Things, structural health monitoring (SHM), and intelligent transportation. It would be more demanding for the power supply to these sensors during the long-term maintenance of the rail transit system. The wind pressure/velocity generated by high-speed trains poses a substantial threat to safety of human, and new sensors without an external power supply should be developed to monitor wind pressure/velocity in the trackside. Flexible self-powered wind triboelectric nanogenerator (W-TENG) sensor with a single-electrode mode based on conductive hydrogel is designed to wind pressure/velocity monitoring without power supply by harvesting wind energy. It is devoted the relationship between the output voltage of the sensors and the wind pressure/velocity driven by high-speed trains. Material selection and structural design methods are adopted to enhance the energy harvesting efficiency and sensing accuracy of self-powered W-TENG sensors. Open-circuit current of 2.8 μA and open-circuit voltage of 12 V are achieved, and the output voltage signal has the linear relationship with trackside wind pressure/velocity. Field tests are implemented to evaluate the performance of self-powered W-TENG sensors in wind pressure/velocity measurement caused by moving trains, providing an idea to SHM application in intelligent transmit systems.

Charge generation by passive plant leaf motion at low wind speeds: design and collective behavior of plant-hybrid energy harvesters

Energy harvesting techniques can exploit even subtle passive motion like that of plant leaves in wind as a consequence of contact electrification of the leaf surface. The effect is strongly enhanced by artificial materials installed as ‘artificial leaves’ on the natural leaves creating a recurring mechanical contact and separation. However, this requires a controlled mechanical interaction between the biological and the artificial component during the complex wind motion. Here, we build and test four artificial leaf designs with varying flexibility and degrees of freedom across the blade operating on Nerium oleander plants. We evaluate the apparent contact area (up to 10 cm2 per leaf), the leaves’ motion, together with the generated voltage, current and charge in low wind speeds of up to 3.3 m s−1 and less. Single artificial leaves produced over 75 V and 1 µA current peaks. Softer artificial leaves increase the contact area accessible for energy conversion, but a balance between softer and stiffer elements in the artificial blade is optimal to increase the frequency of contact-separation motion (here up to 10 Hz) for energy conversion also below 3.3 m s−1. Moreover, we tested how multiple leaves operating collectively during continuous wind energy harvesting over several days achieve a root mean square power of ∼6 µW and are capable to transfer ∼80 µC every 30–40 min to power a wireless temperature and humidity sensor autonomously and recurrently. The results experimentally reveal design strategies for energy harvesters providing autonomous micro power sources in plant ecosystems for example for sensing in precision agriculture and remote environmental monitoring.

A piezoelectric energy harvester for multi-type environments

Researchers have been studying the harvesting and utilization of mechanical vibration energy in the environment in recent years. Wind energy and water current energy are common energy in natural environment, the composite energy harvesting device that can harvest both wind energy and water energy is rarely reported. In this work, a piezoelectric energy harvester for multi-type environments is proposed, which can be installed in corresponding environments to harvest the wind energy, the water wave energy and the water current energy. In addition, the proposed energy harvesting device can adjust the attitude according to the direction of environmental energy. The energy harvesting principle is discussed and the performance of the device under different working conditions is tested by experiment. In the wind energy experiment, the maximum output power is 21.19 mW at a sustained wind speed of 8 m/s, and in the water energy experiment, the maximum output power is 2.01 mW at a medium infiltration depth and a flow velocity of 0.55 m/s. Finally, functional experiments are carried out to verify that the energy harvesting device proposed in this work can be put into practical use, and has a huge application prospect in long-term energy supply for outdoor microelectronic devices.

Investigation on fixed pitch Darrieus vertical axis wind turbine

Small-scale Darrieus wind turbines have a wide scope in areas that are isolated from the power grid for such small-scale household applications. Applications of wind turbines on house roofs are one potential way to generate electricity from wind energy harvesting in low-wind urban locations. This work studies the aerodynamic behavior of a vertical axis wind turbine based on a MATLAB programming mathematical model. The NACA0021 airfoil profile blade was used in this present research investigation. The turbine was fabricated with dimensions such as chord length, c = 95 mm, blade height, h = 600 mm, and turbine diameter, D = 600 mm. The experimental results of the turbine for air velocity from 1 to 12 ms−1 were used in this paper and compared with analytical results. It has been observed that the fixed-pitch turbine does not start by itself at a low air velocity of 1 to 5 m/s due to a minimum and negative torque.

Performance potential of fully-passive airborne wind energy system based on flapping airfoil

In the field of renewable energy, high-altitude wind energy emerges as a promising source, particularly at altitudes (>300 m) where conventional wind turbines cannot reach. Currently, the Airborne Wind Energy System (AWES) stands as the major technology for high-altitude wind energy harvesting, but confronts challenges including increasing performance enhancement, system robustness, and cost reduction. In response to these challenges, we developed a fully-passive AWES that employs a self-excited flapping airfoil to efficiently transfer wind energy to the ground. We study and optimize this fully-passive AWES with fluid-structure interaction method in a numerical wind tunnel, achieving a notable power coefficient of 1.17 and efficiency of 20 % with an average tether angle near 30°. We find that a thin airfoil with a slight camber near the leading edge outperforms other profiles. Increasing the pitching axis distance, the imbalance distance, the spring stiffness, and the pitching moment of inertia can improve the energy harvesting performance, but decreased the system robustness. We offer essential guidelines for setting initial parameters of the AWES, facilitating the design and deployment of this innovative technology. This work underscore that the fully-passive AWES is capable of realizing high-altitude wind energy harvesting with simplified structure and outstanding energy-harvesting performance.

Polymer-composite triboelectric nanogenerators with hook-shaped electrode for wind energy harvesting

Triboelectric nanogenerators (TENGs) based on the composite of polystyrene (PS) and silver nanowires (Ag-nWs) have been investigated. With open-circuit voltage, short-circuit current and power density of ∼200 V, ∼15 μA and ∼395 mW/m2 respectively in the contact separation mode, these TENGs exhibit highly reliable performance. To harvest the wind energy, a novel hook-shape geometry of the top fluttering electrode is demonstrated which is constructed using light-weight rectangular aluminum foil and is fixed at both ends. With PS:Ag-nW composite film, the hook-shaped-electrode TENG (HSE-TENG) provided an average VOC of 15 V, ISC of 0.75 μA and a power density of 18.33 mW/m2 at a wind speed of 5.5 m/s. Under high outdoor temperature and humidity levels, HSE-TENG demonstrated a high degree of response stability. In addition, the proposed TENG is affixed on the top surface of a moving vehicle, where it has been demonstrated to scavenge the energy from the experienced wind force. This study indicates that material strategies and device design approaches can be amalgamated to achieve high performance and operational robustness together for a specific application regime.

A Blade-Type Triboelectric-Electromagnetic Hybrid Generator with Double Frequency Up-Conversion Mechanism for Harvesting Breeze Wind Energy.

Triboelectric nanogenerators (TENGs) have garnered substantial attention in breeze wind energy harvesting. However, how to improve the output performance and reduce friction and wear remain challenging. To this end, a blade-type triboelectric-electromagnetic hybrid generator (BT-TEHG) with a double frequency up-conversion (DFUC) mechanism is proposed. The DFUC mechanism enables the TENG to output a high-frequency response that is 15.9 to 300 times higher than the excitation frequency of 10 to 200 rpm. Coupled with the collisions between tribomaterials, a higher surface charge density and better generating performance are achieved. The magnetization direction and dimensional parameters of the BT-TEHG were optimized, and its generating characteristics under varying rotational speeds and electrical boundary conditions were studied. At wind speeds of 2.2 and 10 m/s, the BT-TEHG can generate, respectively, power of 1.30 and 19.01 mW. Further experimentation demonstrates its capacity to charge capacitors, light up light emitting diodes (LEDs), and power wireless temperature and humidity sensors. The demonstrations show that the BT-TEHG has great potential applications in self-powered wireless sensor networks (WSNs) for environmental monitoring of intelligent agriculture.

High performance piezoelectric nanogenerator by fiber microstructure engineering toward self-powered wireless sensing system

Piezoelectric nanogenerator (PENG) with these advantages of low cost, small volume and stable output in extreme environment is constantly required to develop self-powered sensing system in Internet of Things (IoT), which can relieve energy crisis and reduce labor maintenance costs. However, low electrical output of PENG severely restricts its application and has been a key challenge in the development of PENG. To attain high output performance, a new PENG based on core-shell heterostructure of barium titanate(BT)/polyvinylidene fluoride(PVDF) composite fibers coated with BT@Ag was designed for energy harvesting and wireless sensing application. The outputs of PENG with this special structure are enhanced near 3 times than that of PENG based on traditional fibers, benefiting from the enhanced induced-polarization and stress transfer mechanism in PENG, which is confirmed by experimental results and explained by multi-physics simulations. Moreover, the PENG can effectively harvest wind and acoustic energy, which can deliver the high outputs of 107.5 V and 16.18 µA under 12 m/s wind speed, 45.4 V and 6.5 µA under 110 dB sound pressure, respectively. To verify the practicability of the PENG, a whole self-powered wireless sensing system based on the PENG to harvest energy in environment was demonstrated, where the signal of humidity condition of soil can be sensed periodically and transmitted to mobile phone for further analysis. This work provides an effective strategy to boost performance of PENG and further paves a route about advanced self-powered wireless sensing technology in IoT.

A bladeless wind-tunnel generator based on a flutter-driven triboelectric nanogenerator with on-demand micro-structuring

With the unremitting demand for renewable energy sources, triboelectric nanogenerators as efficient micro-energy, particularly wind-energy harvesting devices, have garnered increased attention. This study introduces an innovative wind flutter-driven triboelectric nanogenerator (WF-TENG). It employs an on-demand integrated design of a "mortise and tenon" microstructure and is assembled in a "negative-positive-negative" configuration mimicking a "corrugated paper" macrostructure, effectively converting wind energy into electrical energy. The porous crosslinked ethyl cellulose/polyethyleneimine positive friction layer and the bionic rose-petal-like fluorinated ethylene propylene negative friction layer are assembled to form a miniaturized "mortise and tenon" structure, which greatly improves the charge transfer efficiency. Surprisingly, due to the collaborative structural design on micro-/macro-scale, WF-TENG elevates the breakthrough power density of WF-TENG to 455.932 mW cm−2. Further, the integrated-equipped bladeless wind tunnel generator, assembled with the WF-TENG array, utilizes airflow disturbances to produce high-frequency flutter-driven frictional motions. This system outputs up to 7.5 kV at a startup wind speed of 7.9 m s−1 and maintains stable performance for 60 days. Application experiment substantiates the ample electrical energy collected by the bladeless wind tunnel generator for powering an indoor formaldehyde purifier demonstrates a high formaldehyde purification rate of 94 %, providing new insights for the design and applications of novel micro-energy harvesting devices.

Wind energy harvesting using electromagnetic dual and multi cantilever flutter array

This study investigates wind energy harvesting from electromagnetic dual cantilever flutter (DCF) and multi cantilever flutter (MCF) arrays. Initially, the bare DCF was tested under several wind speeds at four different gap distances to analyse and verify its behaviour. Results suggest that the characteristics of the DCF is ideal for electromagnetic energy harvesting. Two identical sets of wounded coils and magnets were then fixed onto the DCF to generate an induced voltage output from the anti-phase motion. Experimental findings demonstrated a significant power density of 11 × 10−3 mW/cm3 at a wind speed of 18.0 ms−1 when using shorter and thicker beams, which is comparable to previous flutter-based energy harvesters. An additional magnet-holding beam was then added beside the DCF beams to form a multi cantilever flutter (MCF) array of three identical beams. Visual observation confirms that alternate beams in the MCF array also flutter in an anti-phase motion. The power output per beam and power density recorded for the MCF array was 38.0% higher than the DCF harvester due to the increase in functional coil output and magnetic flux density. Finally, further analysis suggest that an odd number of beams is more favourable for electromagnetic MCF array harvesters.