Energy Harvesting Performance Research Articles

Energy harvesting of a metamaterial beam with acoustic black holes

Abstract This paper proposed an improved metamaterial piezoelectric beam with the acoustic black holes (ABHs) for low-frequency energy harvesting. The ABHs are embedded in the local resonant beams distributed on both sides of the primary beam. Piezoelectric plates are attached to the ABHs, leveraging the energy-focusing effect to enhance the energy harvesting performance. Finite element simulation results indicate that the energy harvesting electrical energy has improved by 6.92 times compared to the traditional metamaterial resonant beam without ABHs. Parameter analysis indicates that increasing the number of local resonators and extending the length of the piezoelectric patches can further enhance energy harvesting performance. However, reducing the truncation thickness of the ABH boosts energy harvesting but compromises structural strength. Extending the ABH length and increasing load resistance within the appropriate range are conducive to energy harvesting. Besides, the optimal load resistance varies with frequency. These findings provide useful guidance for future applications of improved metamaterial beam.

Performance estimation of a piezoelectric energy harvester with rotatable external magnets.

This study estimates the performance of a piezoelectric energy harvester (PEH) with rotatable external magnets from the viewpoint of global dynamics. According to static analysis of the PEH dynamic system, the monostable and bistable potential wells are configured under different values of the inclined angle of the external magnets. In the monostable case, the method of multiple scales is applied for the analysis of periodic responses, while the extended averaging method and the Melnikov method are utilized to analyze the periodic and chaotic responses in the bistable case. Numerical results are in great agreement with the theoretical ones. It follows from the comparison of the dynamical behaviors in the two cases that the bistable-well configuration is more efficient in harvesting vibration energy under low-frequency or low-level ambient excitation. In the bistable case, sequences of the coexisting attractors and basins of attraction (BAs) with the increase in the excitation strength are presented, illustrating that the inter-well periodic and chaotic responses can be successively triggered by the rise in the excitation level, and which attractor will contribute to increasing the voltage output depends on the location and size of their BAs. With the increase in the excitation level, rich nonlinear dynamic phenomena, such as multistability, period-2 attractors, chaos, fractal BAs, and hidden attractors, can be observed.

A novel passive flow control technique using circular arcs coupled with downstream splitters

The current study presents a novel piezoelectric design that converts vortex-induced vibrations caused by flow across a circular cylinder. This design can be implemented as a passive control method for energy harvesting. It encompasses the novelty of employing circular arc plates around a circular cylinder integrated with flexible splitters downstream. To assess the merits of the proposed design, a comprehensive parametric study for flexible splitters is conducted to specify the optimum layout of piezoelectric harvesters. The analysis is carried out at a low Reynolds number, , at which accurate non-intrusive experimental assessment of flow structure is difficult. The results indicate that the drag can be halved by adding circular arc plates to the cylinder. Moreover, it is demonstrated that the plate displacement increases by 18.29 folds for dual splitters compared with a single plate. By adding the arc plates, a further increase of 3.97 folds is obtained. Following this, the maximum strain with the inclusion of arc plates is 170.17% higher than the cylinder without arc plates (bare cylinder) for dual flexible splitters downstream, enhancing the energy harvesting performance remarkably. Finally, using the proposed design, the generated electrical power figures out at at 77.7% conversion efficiency.

Balancing Surface Chemistry and Flake Size of MXene-Based Electrodes for Bioelectrochemical Reactors.

MXenes have excellent properties as electrode materials in energy storage devices or fuel cells. In bioelectrochemical systems (for wastewater treatment and energy harvesting), MXenes can have antimicrobial characteristics in some conditions. Here, different intercalation and delamination approaches to obtain Ti3C2Tx MXene flakes with different terminal groups and lateral dimensions are comprehensively investigated. The effect of these properties on the energy harvesting performance from wastewater is then assessed. Regardless of the utilized intercalant molecules, MXene flakes obtained using soft delamination approaches are much larger (up to 10µm) than those obtained using mechanical delamination methods (<1.5nm), with a relatively higher content of ─O/─OH surface terminations. When employed in microbial fuel cells, electrodes made of these large MXene flakes have demonstrated a power density of over 400% higher than smaller MXene flakes, thanks to their lower charge transfer resistance (0.38Ω). These findings highlight the crucial role of selecting appropriate intercalation and delamination methods when synthesizing MXenes for bioelectrochemical applications.

Development of a multi-physics numerical model for a multi-component thermoelectric generator with discontinuous porosity in the exhaust gas channel

A critical technical challenge in the energy harvesting performance of a thermoelectric generator (TEG) is the optimal utilization of the thermal energy from exhaust gas. In most TEG applications, the exhaust gas flowing through the exhaust channel exhibits high inertia forces, causing significant temperature maldistribution on the hot surfaces of thermoelectric modules (TEMs). To address this challenge, we developed a numerical model that incorporates the primary multi-physics phenomena associated with TEGs, designed with a porous flow conditioner and extended surfaces for practical use. A reliable three-zone method is employed to simulate thermoelectric energy conversion phenomena, including the resulting heat pumping and Joule heating effects in individual TEMs. The model accounts for the communication effect between electrically connected TEMs by integrating Kirchhoff’s voltage and current laws into the solving process. A selective porous media method is proposed for accurately analyzing the pressure jump induced by the flow conditioner and the porosity jump occurring at the interfaces between the flow conditioner and plate fins while ensuring model convergence reliability. The developed numerical model aligns with experimental results, showing a maximum error of 5 %. Comprehensive analyses of TEM-wise heat absorption rates and channel-wise flow distribution characteristics were conducted to identify the optimal position and porosity of the flow conditioner. The findings demonstrate that optimal use of the flow conditioner improves the net output power of the TEG by 31.5 % compared to the case without any flow conditioner.

Modeling and Optimization of Energy Harvesters for Specific Applications Using COMSOL and Equivalent Spring Models

Energy harvesting from natural sources, including bodily movements, vehicle engine vibrations, and ocean waves, poses challenges due to the broad range of frequency bands involved. Piezoelectric materials are frequently used in energy harvesters, although their effectiveness depends on aligning the device’s natural frequency with the frequency of the target energy source. This study models energy harvesters customized for specific applications by adjusting their natural frequencies to match the required bandwidth. We evaluate commercially available piezoelectric transducers and model them using COMSOL Multiphysics alongside an equivalent spring-mass schematic approach, enabling precise adjustments to optimize energy capture. The proposed system achieves a maximum power output of 160 µW and a power density of 187.35 µW/cm3 at a natural frequency of 65 Hz. Furthermore, the theoretical maximum power density is calculated as 692.97 W/m3, demonstrating the system’s potential for high energy efficiency under optimal conditions. Simulations are validated against experimental data to ensure accuracy. Our findings provide a design framework for optimizing energy harvester performance across diverse energy sources, leading to more efficient and application-specific devices for varied environmental conditions.

Study on energy harvesting performance of a tidal current turbine based on three pitching circular motion hydrofoils using numerical method

If the pitching hydrofoil moves following a circular trajectory, the turbine can use multiple hydrofoils to capture energy from the current, which has the potential to improve efficiency. In this study, by solving Reynolds-averaged Navier-Stokes equation with Shear Stress Transport k-ω model, hydrodynamic performance of the new turbine with three hydrofoils was investigated. First, energy harvesting performance of the turbine with a wide range of motion parameters was studied. Then, based on the optimal operating condition, energy harvesting principle of the turbine was analyzed from the perspectives of vortex-body interactions, hydrodynamic forces and energy parameters. Finally, the fundamental reasons for the variation of efficiency with motion parameters were investigated. Results show that the maximum efficiency reaches about 50%, much higher than that of turbines of the same type with one hydrofoil and the vertical axis turbine. The turbine harvests energy mainly through the circular motion and the lift is the main driving force for the turbine to harvest energy. At the optimal motion parameters, the interactions between vortex and hydrofoil is favorable, which increases the positive work done by the lift and reduces the energy consumed by the horizontal force and pitch moment at specific moments, thereby improving the efficiency.

Next-generation hybrid nanogenerators using giant piezoelectric lead-free KNNS composites for sustainable self-powered electronics

This study presents a flexible hybrid nanogenerator that utilizes lead-free KNNS-BF-xBNZ materials integrated with polydimethylsiloxane (PDMS) to enhance energy harvesting performance. The findings demonstrate that by combining piezoelectric and triboelectric effects, the energy conversion efficiency of the nanogenerator is significantly improved, resulting in high output voltage and current, suitable for real-world applications. Specifically, the optimal composition of KNNS-BF-xBNZ ceramics, with x = 0.03 mol.%, yields superior piezoelectric, ferroelectric, and dielectric properties, with remnant polarization (Pr), spontaneous polarization (Ps), and piezoelectric coefficient (d33) values reaching 18.8 μmC/cm², 30.3 μmC/cm², and 358 pC/N, respectively. In the hybrid device, incorporating 15 wt% of KNNS-BF-3BNZ into PDMS resulted in the highest open-circuit voltage (VOC) of 107 V and short-circuit current (ISC) of 4.68 μA. The developed hybrid nanogenerator effectively charges capacitors for energy storage, powers LEDs, and drives small electronic devices, such as watches, showcasing its potential for practical energy harvesting applications. The findings suggest that the integration of KNNS-BF-3BNZ with PDMS provides an efficient and scalable pathway for fabricating high-performance nanogenerators, paving the way for advancements in self-powered devices and sustainable energy solutions.

A Self‐Powered and Self‐Absorbing Wireless Sensor Node for Smart Grid

The health monitoring of electricity transmission systems has been increasingly attracting the scientific community's attention, especially those power transmission towers built in remote and deserted areas. The smart grid provides a realistic solution to the health monitoring problem, but there is a problem that the energy supplies are still constrained by batteries. This article proposes a novel vibration energy harvester to address the power supply challenges of auxiliary equipment mounted on electricity towers or transmission lines. The proposed harvester not only harvests vibration energy when working but also attenuates the vibration amplitude of the transmission line. The structure of the device comprises three modules: a module for capturing vibration, a module for motion conversion, and a power management module. The analytical response under sinusoidal and random excitation is investigated, and the performance of energy harvesting and the effect on vibration is tested. The prototype achieves a maximum power of 183.96 mW when tested using the servo hydraulic mechanical testing and sensing system, and the wireless data transmission experiment proves the power generation ability of the prototype. The experimental results show that the acceleration of the transmission line decreases when the prototype is working.

Optimization of energy acquisition system in smart grid based on artificial intelligence and digital twin technology

In response to the low operating speed and poor stability of energy harvesting systems in smart grids, an energy harvesting optimization method based on improved convolutional neural networks and digital twin technology is proposed in the experiment. Firstly, a smart grid data transmission framework integrating digital twin technology is proposed. A digital twin mapping method based on time, data, and topology structure is used to realize the digital twin mapping at the device level of power grid. Through data synchronization and interaction between the physical power grid and the digital twin model, the operational efficiency and reliability of the power grid are improved. Then, the classical convolutional neural network and attention mechanism are used to comprehensively analyze the physical topology data in the smart grid energy acquisition system. The improved lightweight target detection model is combined to monitor the equipment status of the smart grid and extract key features. Simultaneously utilizing convolutional attention mechanism to dynamically adjust the feature weights of channels or spaces, completing the preprocessing of energy harvesting data. Finally, combined with energy harvesting and power grid switching system, the process of energy harvesting and power grid operation are optimized together. On the training and validation sets, when the channels exceeded 60, the proposed method achieved a system energy efficiency of 55% during operation. The system energy efficiency of the other three comparative algorithms was all less than 40%. In practical applications, as the energy transfer loss increased to 1.0, the system throughput increased to 50 bits. The electricity needs of different users were met, and the difference between power allocation and optimal power allocation was small, which was very reasonable. This proves that the research has effectively optimized the energy harvesting system in the smart grid, improving the efficiency and reliability of the system in practical applications of the smart grid. At the same time, in the increasingly severe energy problem, this system can further provide technical references for the utilization of renewable energy and help achieve the goal of sustainable energy.

Study on physical, electrical, magnetic and energy harvesting performances of eco-friendly piezoelectric ceramics (1 − x)[0.995BNKT–0.005LN]–xFe2O3 complex system

ABSTRACT In this work, the complex lead-free piezoelectric ceramics with formula (1 − x)[0.995 Bi0.5(Na0.80K0.20)0.5TiO3–0.005LiNbO3]–xFe2O3, where x = 0, 0.010, 0.015 and 0.020 mol fraction, have been prepared via a conventional solid-state method. The effects of Fe2O3 doping on the physical, microstructural electrical, energy harvesting and magnetic properties have been systematically investigated. All ceramics were sintered at 1150°C for 2 hours with obtained relative density of ~ 96-97%. The XRD and Raman data revealed the coexisting rhombohedral and tetragonal phases for all samples. SEM image presented angular grain packing with the average grain size range of 0.43–1.03 μm. The addition of Fe2O3 content improved in electrical properties of undoped sample particularly at a composition of x = 0.015. The maximum values of ε m = 6250, S max = 0.29, d*33 = 578 pm/V, d 33 = 211 pC/N and FOM = 3.54. All ceramics indicated ferromagnetic behavior with slim hysteresis shape. The results suggest a potential for its applications as an eco-friendly compound for further use in sensor, spintronic and microelectronic devices applications.

Improving energy storage density, piezoelectric, and energy harvesting performances of eco-friendly (Bi0.49−xBaxLa0.01Na0.40K0.10)TiO3 ceramics by composition design strategy

Improving energy storage density, piezoelectric, and energy harvesting performances of eco-friendly (Bi0.49−xBaxLa0.01Na0.40K0.10)TiO3 ceramics by composition design strategy

Improved Pyroelectric Nanogenerator Performance of P(VDF-TrFE)/rGO Thin Film by Optimized rGO Reduction.

The pyroelectric nanogenerator (PyNG) has gained increasing attention due to its capability of converting ambient or waste thermal energy into electrical energy. In recent years, nanocomposite films of poly(vinylidene fluoride-co-trifluoro ethylene) (P(VDF-TrFE)) and nanofillers such as reduced graphene oxide (rGO) have been employed due to their high flexibility, good dielectric properties, and high charge mobility for the application of wearable devices. This work investigated the effect of rGO reduction on pyroelectric nanogenerator performance. To prepare rGO, GO was reduced with different reducing agents at various conditions. The resulting rGO samples were characterized by XPS, FT-IR, XRD, and electrical conductivity measurements to obtain quantitative and qualitative information on the change in surface functionalities. Molecularly thin nanocomposite films of P(VDF-TrFE)/rGO were deposited on an ITO-glass substrate by the Langmuir-Schaefer (LS) technique. A PyNG sandwich-like structure was fabricated by arranging the thin films facing each other, and it was subjected to the pyroelectric current test. For various PyNGs of the thin films containing rGO prepared by different methods, the average pyroelectric peak-to-peak current (APC) and the pyroelectric coefficient (p) values were measured. It was found that a more reduced rGO resulted in higher electrical conductivity, and the thin films containing rGO of higher conductivity yielded higher APC and p values and, thus, better energy-harvesting performance. However, the thin films having rGO of too high conductivity produced slightly reduced performance. The Maxwell-Wagner effect in the two-phase system successfully explained these optimization results. In addition, the APC and p values for the thin film with the best performance increased with increasing temperature range. The current PyNG's performance with an energy density of 3.85 mW/cm2 and a p value of 334 μC/(m2∙K) for ΔT = 20 °C was found to be superior to that reported in other studies in the literature. Since the present PyNG showed excellent performance, it is expected to be promising for the application to microelectronics including wearable devices.

Enhancement of wave energy harvesting performance by wave concentration with vertical cylinders

The performance of ocean wave energy harvesting can be enhanced by optimizing the design and operation of wave energy converters (WECs). In this experimental study, we investigate the wave interaction produced by installing additional structures to augment the power and efficiency of a WEC. Four circular cylinders are arranged in a square within a large-scale ocean engineering basin, and a duck-type rotor WEC is placed at the center of the cylinders. Several incident wave conditions are generated by varying the wavelength and wave height for a fixed wave steepness. In the absence of the rotor, the waves scattered by the cylinders become concentrated at the center of the array, increasing their amplitudes. With the rotor, wave heights in front of the rotor increase under all wave conditions from the case without the cylinders. The wave concentration produced by the cylinder array contributes positively to the power and efficiency of the rotor. The maximum power output of the rotor within a cycle improves in the entire range of the wavelength, and its efficiency over a cycle increases significantly for small wavelengths. These results are primarily attributable to changes in the temporal profile of the rotor angular velocity by the cylinder array.

Energy harvesting properties for potassium-sodium niobate piezoceramics through synergistic effect of phase structure and texturing engineering

In order to address the energy dilemma and meet environmental protection requirements, it is an urgent need to develop lead-free piezoelectric energy harvesters (PEHs). However, the low output power density has seriously hindered the application of lead-free piezoceramics as high efficiency energy harvesters. To solve above question, the combination of phase structure regulation and texturing technique in the K0.5Na0.5NbO3-xBi0.5Na0.5ZrO3-0.5%wtBiFeO3 (KNN-xBNZ) ceramics was adopted in this work. Because of both the Rhombohedral-Orthorhombic-Tetragonal (R-O-T) multiphases coexistence and texturing engineering, an ultrahigh piezoelectric activity quality factor d33×g33 ∼ 18324 ×10-15 m2·N-1 was achieved in the textured KNN-0.05BNZ (T-KNN-0.05BNZ) ceramics, which is about third times higher than that of random KNN-0.05BNZ (R-KNN-0.05BNZ) (d33×g33 ∼ 6672 ×10-15 m2·N-1) ones. A high output power of ∼ 0.32 mW was also obtained in the T-KNN-0.05BNZ ceramics by cantilever beam-based energy harvester devices under the resonance frequency of 75 Hz and matched RL of 1.2 MΩ, suggesting that the T-KNN-0.05BNZ ceramics have a great potential for application in the PEHs devices. This result also reveals that the combination of phase structure regulation and texturing technique is an effective way to achieved a high energy harvesting performances.

A hybrid triboelectric-piezoelectric-electromagnetic generator with the high output performance for vibration energy harvesting of high-speed railway vehicles

With the rapid development of intelligent high-speed train, people's travel becomes more convenient, time-saving and comfortable. However, the increase in the number of equipped electronic facilities also brings more power consumption. While the ultra-high voltage drive power system cannot directly drive its numerous devices and the vibrational energy of high-speed trains is completely abandoned. Herein, a hybrid triboelectric-piezoelectric-electromagnetic generator (HTG) is proposed to drive the signal and sensing devices of high-speed train by in-situ harvesting the corresponding vibration energy. Compared with commercial polyformaldehyde film, the output power of triboelectric nanogenerator with the polyformaldehyde nanofiber film prepared by electrospinning technology is improved by 130 times. Furthermore, thanks to the high space utilization and output performance, the HTG has achieved a power-density of the order of kW/m3, which is an improvement of 1–3 orders of magnitude compared to previous research work on vibration energy collection. Importantly, the self-powered wireless motion monitoring system based on HTG can realize real-time monitoring and transmission of motion information such as speed, frequency and displacement. This finding not only gives an important way to efficiently harvest vibration energy, but also provides new ideas for the design of more economical, comfortable and intelligent high-speed trains.

Vibration Suppression and Energy Harvesting of Nonlinear Energy Sink-Based Piezoelectric System with Combined Damping and Bistability Properties for Nonlinear Oscillator

Nonlinear energy sink (NES) as a new type of dynamic absorber has received widespread attention due to its broadband vibration suppression capability, but it has a certain requirement of energy triggering threshold. In this work, a bistable NES-based piezoelectric system with combined damping (BCPNES) and low threshold requirement is proposed. Electromechanical-coupled equations for the nonlinear oscillator coupled with BCPNES (NO-BCPNES) are established. The vibration suppression and vibration energy harvesting performance for the coupled system are investigated numerically and analytically. The frequency–energy plots of the conservative system are investigated using the complex-variable averaging method and the electromechanical decoupling method. The influence of circuit parameters on the target energy transfer threshold and harvested energy is discussed through the equivalent stiffness and damping of the circuit. The vibration suppression performance and the target energy transfer characteristics are analyzed in terms of the time–history response, the time–frequency response and the slowly varying dynamic flow, respectively. The results show that the electromechanical coupling coefficient affects the skeleton curve of frequency–energy plots in the form of equivalent stiffness. The NO-BCPNES system exhibits higher energy dissipation performance and better targeted energy transfer form under various excitations. From the phase perspective, NES-based piezoelectric system achieves vibration suppression of the main structure through the phase locking phenomenon. The mechanism of the influence of piezoelectric device parameters on the energy harvesting performance of the systems is clarified.

Enhanced energy harvesting in low-velocity water by downstream interference for piezoelectric energy harvester

The vibration of a single-degree-of-freedom bluff body positioned in water is intensified by the positive excitation, which is affected by the upstream interfering body and also by the downstream obstacles. This paper investigates the effect of downstream interference on galloping piezoelectric energy harvester performance. A mathematical model of the piezoelectric energy harvester under disturbance is established based on the extended Hamilton’s principle, and the theoretical output is further derived. The accuracy of proposed model is verified by the results of circulating water channel experiment. The effect of interference shape and approximate spacing (L/D) on system output is further analyzed, and the results show that the harvester performance is substantially improved when the distance between the bluff body and downstream interference is sufficiently small, and the interference is an elliptical cylinder with an aspect ratio of 0.6, i.e., the output power is 0.624 mW, which is improved by 24.39 % when L/D=1.8 and U=0.5m/s. Precise numerical calculations are further utilized to indicate that the harvester’s output performance is optimal when the downstream interference angle is 30°.

Simulation and Experiments on Optimization of Vortex-Induced Vibration Power Generation System Based on Side-by-Side Double Blunt Bodies

In order to improve the utilization efficiency of converting low-flow current energy into electric energy for Reynolds number 10,000 ≤ Re ≤ 40,000, this paper proposes a vortex-induced vibration power generation system based on a side-by-side double blunt body. In this system, the side-by-side double blunt body structure is used in the current energy capture part to enhance the collection of low-flow current energy; the permanent magnet linear motor is used in the electric energy conversion part to improve the efficiency of electric energy conversion; and a laboratory device is constructed for testing. The effects of the blunt body structure parameters and the center spacing ratio on the energy harvesting performance of the system are qualitatively explained by constructing a simulation model. Compared with the single blunt body energy capture structure, the side-by-side double blunt body structure increases the vibration amplitude by 1.04 times and the lift by 1.14 times at the center spacing S/D = 2.4. Meanwhile, energy harvesting can be realized at a lower flow velocity, increasing the vortex-induced vibration’s energy capture range. Finally, the power generation system was experimentally verified in the laboratory, and the results showed that the vibration amplitude of the double blunt body structure was increased by 1.12 times compared to the single blunt body. The maximum output power of the generator is 10.55 W when the water velocity is 0.7 m/s. The energy conversion efficiency of the power generation system can reach a maximum of 52.93%, which is 12.33% higher than that of a single blunt body structure, which proves that the system has a higher power conversion efficiency than that of a conventional single conversion system.

Ferroelectric Nanomaterials for Energy Harvesting and Self‐Powered Sensing Applications

AbstractThe rapid development of the Internet of Things has introduced new challenges for miniaturized, highly integrated energy harvesters and sensors, promoting the exploration of various novel nanomaterials. Ferroelectric nanomaterials, characterized by large remanent polarization, exceptional dielectric properties, outstanding chemical stability, and diverse electricity generation capabilities, are emerging as promising candidates in a variety of fields. Possessing various mechanisms for electricity generation, including piezoelectric, pyroelectric, photovoltaic, and triboelectric effects, ferroelectric nanomaterials demonstrate their capability for harvesting and sensing multiple energies simultaneously, including light, thermal, and mechanical energies. This capability contributes to the miniaturization and high integration of electronic devices. This article reviews recent achievements in ferroelectric nanomaterials and their applications in energy harvesting and self‐powered sensing. Different categories of ferroelectric nanomaterials, their ferroelectric properties, and fabrication methods are introduced. The working mechanisms and performance of ferroelectric energy harvesters and self‐powered sensors are described. Additionally, future prospects are discussed.