Low-frequency Water Wave Research Articles

Durable Multilayered Sleeve-Structured Hybrid Nanogenerator for Efficient Water Wave Energy Harvesting.

The state-of-the-art triboelectric nanogenerator (TENG) technology has numerous advantages and creates new prospects for the rapid development of the Internet of Things (IoT) in marine environments. Here, to accelerate the application process of TENG, an elaborately designed multilayered sleeve-structured hybrid nanogenerator (M-HNG) is developed to efficiently and persistently harvest marine energy. The M-HNG integrates an electromagnetic nanogenerator (EMG) with four coils and a multilayered sleeve-structured TENG (MS-TENG) with three freestanding layer units to increase spatial utilization efficiency. Moreover, rabbit fur strips are introduced to enhance the output performance and strengthen the durability of TENG. Therefore, the MS-TENG has high durability due to its soft-contact structure, maintaining its performance even after 240,000 cycles. When a 1000 μF capacitor is charged by M-HNG utilizing a power management circuit (PMC), the stored energy is increased from 2.62 mJ to 140.11 mJ, representing a significant improvement of 52-fold. The M-HNG triggered by water waves has successfully powered various small electronic devices, including 1200 LED lights, nine thermo-hygrometers, a water quality testing pen, and water level alarms. The proposed M-HNG effectively harvests low-frequency water wave energy, introducing an innovative concept for constructing a hybrid TENG with enhanced density and durability.

Swing Origami-Structure-Based Triboelectric Nanogenerator for Harvesting Blue Energy toward Marine Environmental Applications.

The appearance of triboelectric nanogenerators (TENG) provides a promising energy technology for harvesting abundant water wave energy. Here, the design and fabrication of a swinging origami-structured TENG (SO-TENG) tailored specifically for water wave energy harvesting are presented. The design incorporates an oscillating structure weighted at the bottom, inducing reciprocating motion propelled by the inertia of passing water waves. This reciprocating motion efficiently converts mechanical into electrical energy through the origami structure. By employing origami as the monomer structure, the surface contact area between friction layers is enhanced, thereby optimizing output performance. the swinging structure, combined with the placement of heavy objects, enhances the folding and contact of the origami, allowing it to operate effectively in low-frequency water wave environments. This configuration exhibits robust power generation capabilities, making it suitable for powering small electronic devices in water wave environments. Furthermore, when applied to metal corrosion protection, the SO-TENG demonstrates notable efficacy. Compared to exposed Q235 carbon steel, Q235 carbon steel protected by SO-TENG exhibits a significant reduction in open-circuit potential drop, approximately 155 mV, indicative of superior anti-corrosion properties. It lays a solid foundation for water wave energy collection and self-powered metal corrosion protection in marine environments.

High-Durability Stacked Disc-Type Rolling Triboelectric Nanogenerators for Environmental Monitoring Around Charging Buoys of Unmanned Ships.

Triboelectric nanogenerator (TENG) as a means of energy harvesting can effectively harvest ocean wave energy, but the energy conversion efficiency and stability of the device during long-term operations are still problems that must be solved for TENGs. Decreasing the frictional resistance between two triboelectric material surfaces is one of the critical approaches for improving the device efficiency and durability. In this work, a novel stacked disc-type rolling triboelectric nanogenerator (SDR-TENG) is designed and fabricated for low-frequency water wave energy harvesting. After 860000 working cycles, the electrical output attenuation of the SDR-TENG basic unit is less than 5%, showing excellent device durability. Under the simulated water wave conditions, the SDR-TENG with four rolling TENG units can produce an output current of 84.4µA and an output power of 7.6mW, corresponding to an effective power density of 16.8Wm-3. This work not only proposes a strategy to effectively enhance the durability of the devices, but also provides a feasible solution for monitoring the surrounding environment of the charging buoys of unmanned ships.

Wave energy harvesting based on multilayer beads integrated spherical TENG with switch triggered instant discharging for self-powered hydrogen generation

Effective strategies to gain hydrogen energy from harvesting and conversion from ocean energy attract extensive attention in the new energy source field. Remarkably, triboelectric nanogenerator (TENG) presents potential applications for harvesting large-scale blue energy from the ocean. Herein, we propose a self-powered hydrogen generation system by multilayer beads integrated spherical TENG with the power management system (PMS). The triggered switch used in the spherical TENG overcomes the limitation of working frequency through instantaneous driving, significantly improving the output performance and greatly expanding its application range. The six-layer beads integrated TENG presents a significant improvement in converting water wave energy into electric energy, and its power density reaches 21.3 W m−3 at 2 Hz. The integrated TENG charges 470 μF capacitor to 5 V in 200 s, and the hydrogen production rate is about 64.5 μL min−1 under the water wave condition, which overcomes the limitation of external power demands for conventional water electrolysis. Compared with the electrochemical cells driven by solar, our integrated system can operate in all weather conditions without an external power source. This work demonstrates the feasibility of the electrochemical conversion of low-frequency water wave energy into green energy.

Frequency-multiplied cylindrical triboelectric nanogenerator for harvesting low frequency wave energy to power ocean observation system

Cylindrical triboelectric nanogenerators (C-TENGs) have been designed for low frequency wave energy harvesting. However, the random, and low amplitude and frequency of the ocean waves represent a major challenge for the operation and performance of most C-TENGs. A C-TENG must be able to operate and be triggered by any wave conditions, even in the middle of the ocean, with uniform, low amplitude, and low frequency water waves. Here, a frequency-multiplied cylindrical TENG (FMC-TENG) that uses magnets to store potential energy and instantly release it to produce high frequency kinetic energy, was designed to increase the operating frequency of the TENG using low frequency, uniform water waves and increase the power generated. A semi-analytical modeling of the FMC-TENG was performed to theoretically verify its effectiveness. Then, the electrical characteristics of the FMC-TENG were evaluated by comparison with a conventional C-TENG in a wave motion simulator. The FMC-TENG was optimized in a 12 m long water tank, and its peak power density reached 6.67 W/m3 under a wave frequency of 0.33 Hz. Finally, an array of FMC-TENGs successfully powered an acoustic transmitter, demonstrating the ability to power an ocean observation system.

Active resonance triboelectric nanogenerator for harvesting omnidirectional water-wave energy

<h2>Summary</h2> Water-wave energy, as one of the important renewable energies, is greatly difficult to efficiently harvest due to its characteristics of low frequency and randomly moving direction. Herein, we report an active resonance triboelectric nanogenerator (AR-TENG) system fabricated by using simple pendulum, tumbler, and flexible ring TENG, which can harvest omnidirectional and frequency varying water-wave energy through excellent structural design and resonance effect. Besides, thanks to the high-frequency damped motion of simple pendulum and tumbler, the high-frequency output generated by the AR-TENG system under the driving condition of low-frequency water wave can greatly improve the efficiency of wave energy harvesting. More importantly, based on the low damping coefficient, resonance effect, and elimination of water screening effect, the output performance of AR-TENG system in the water wave is closest to the simulated test. This work not only can realize the omnidirectional water-wave energy harvesting by TENG but also provide a method for large-scale blue energy harvesting.

Spherical triboelectric nanogenerator based on spring-assisted swing structure for effective water wave energy harvesting

Abstract Ocean wave energy is one of the most promising clean and renewable energy sources, so developing effective methods to collect such ‘random’ and ultra-low frequency energy is indispensable. The invention of triboelectric nanogenerators (TENGs) provides new prospects for large-scale blue energy harvesting. In this work, a new spherical TENG based on the coupling of spring-assisted structure and swing structure, integrated with a charge excitation circuit (CEC), was constructed to scavenge water wave energy. The particular structure can transform low-frequency water wave vibrations to high-frequency motions, elevating the frequencies of electrical outputs. Moreover, a TENG array consisting of four TENGs with CECs was fabricated, exhibiting a maximum output power of 16.6 mW and a 205 times enhanced output current of 23.3 mA. The charge excitation TENG array was demonstrated to successfully power a digital thermometer and a wireless signal transmission and reception system without any external power supply. Our study not only provides a new type of TENG with improved performance, but also offers a strategy for constructing maritime internet of things (IoTs) system.

Stacked pendulum-structured triboelectric nanogenerators for effectively harvesting low-frequency water wave energy

The invention of triboelectric nanogenerators (TENGs) provides an effective approach for harvesting water wave energy that is clean and renewable. Here, stacked pendulum-structured triboelectric nanogenerators for harvesting low-frequency water wave energy is proposed. The device works based on a pendulum-like principle through a compact disk-track structure that enables area contact instead of point contact while maintaining the susceptible rolling motion. Thus the tribo-electrification and the output are greatly enhanced in slow water waves. While only considering the volume of the TENG units, charge output density of 4622 μC m−3 can be achieved, which is more than 13.2 times of a typical ball-shell structured device. A peak power density of 14.71 W m−3 and an average power density of 1.05 W m−3 are obtained in low-frequency water waves below 0.5 Hz. The device shows great potential of the rolling area-contact design to enhance the output of TENG-based wave energy harvester with excellent low-frequency performance, which is crucial to the development of TENGs for effectively exploiting abundant water wave energy.

Harvest of ocean energy by triboelectric generator technology

Water wave energy widely distributed in the globe is one of the most promising renewable energy sources. However, it has not been effectively exploited by current energy harvesting technologies which primarily rely on electromagnetic generator (EMG). EMG's have various limitations, especially when operating in environment with irregular and/or low frequencies ( < 5 Hz) wave motions. Triboelectric nanogenerators (TENGs) exhibit obvious advantages over EMG in harvesting energy from low-frequency water wave motions. The networking of TENGs has been regarded as a potential method towards large-scale blue energy harvesting. In this review, recent progress of the TENG technology for blue energy harvesting is presented, including a comparison between TENG and EMG in physics and engineering design, and the fundamental mechanism of nanogenerator based on Maxwell's displacement currents is systematically introduced. The review of hydrodynamic TENG, liquid-solid contact electrification TENG, hybrid (dual-modes) TENG, fully enclosed TENG, and TENG network for blue energy harvesting is discussed. The TENG networks are expected to harvest large-scale blue energy from the ocean, which will be a feasible approach for realizing the blue energy dream. Moreover, the energy harvested by TENG from various sources, such as human motion and vibration, is not only new energy, but more importantly, energy using for the new era-the era of internet of things.At the request of the authors, this article is being retracted effective 15 May 2019.

Silicone-Based Triboelectric Nanogenerator for Water Wave Energy Harvesting.

Triboelectric nanogenerator (TENG) has been proven to be efficient for harvesting water wave energy, which is one of the most promising renewable energy sources. In this work, a TENG with a silicone rubber/carbon black composite electrode was designed for converting the water wave energy into electricity. The silicone-based electrode with a soft texture provides a better contact with the dielectric film. Furthermore, a spring structure is introduced to transform low-frequency water wave motions into high-frequency vibrations. They together improve the output performance and efficiency of TENG. The output performances of TENGs are further enhanced by optimizing the triboelectric material pair and tribo-surface area. A spring-assisted TENG device with the segmented silicone rubber-based electrode structure was sealed into a waterproof box, which delivers a maximum power density of 2.40 W m-3, as triggered by the water waves. The present work provides a new strategy for fabricating high-performance TENG devices by coupling flexible electrodes and spring structure for harvesting water wave energy.

Spring-assisted triboelectric nanogenerator for efficiently harvesting water wave energy

Ocean waves are one of the most promising renewable energy sources for large-scope applications. Triboelectric nanogenerator (TENG) has been demonstrated to effectively harvest water wave energy possibly toward large-scale blue energy. In this work, a kind of spring-assisted TENG was designed and investigated for harvesting water wave energy. The idea of introducing spring is to store the potential energy built during mechanical triggering for multiple cycles of conversion into electricity afterward, and transform a low frequency motion into a high frequency oscillation for improving the energy harvesting efficiency. The output performance of the basic unit was optimized by adjusting the motor acceleration and spring parameters including the rigidity and length. There exists an optimized spring rigidity or spring length to produce the highest performance. By using the spring, the accumulated charge of the TENG can be increased by 113.0%, and the translated electric energy or efficiency can be improved by 150.3%. Then four optimized basic units were connected in parallel and packaged into a sealed box to harvest the water wave energy. The present work could provide an approach to improving the output performance and efficiency of TENGs in harvesting low-frequency water wave energy.

Experimental studies on dragon wash phenomena

Abstract The experiment is carried out to study the low frequency surface waves due to the horizontal high frequency excitation. The viscous effect of water was neglected as a first approximation in the earlier papers on this subject. In contrast, we find the viscosity is important to achieve the low frequency water wave with the cooperation of hundreds of “finger” waves. Shadowgraphs have been taken qualitatively using laser sheet and vertical velocities of surface waves have been measured quantitatively by Polytec Scanning Vibrometer. The viscous cooperation effects are shown to be the most important mechanism for the dragon wash phenomena.

NONLINEAR LOW FREQUENCY WATER WAVES IN A CYLINDRICAL SHELL

The experiment was carried out to study the low frequency surface waves due to the horizontal high frequency excitation. The feature of the phenomenon was that the big amplitude axisymmetric surface wave frequency was typically about 1/50 of the excitation frequency. The viscous effect of water was neglected as a first approximation in the earlier papers on this subject. In contrast, we found the viscosity was important to achieve the low frequency water wave with the cooperation of hundreds of "finger" waves. Photographs were taken with stroboscopic lighting and thereafter relevant quantitative results were obtained based on the measurements with Polytec Scanning Vibrometer PSV 400.